032123-C-8 Corresp. Elkins.pdf — Long Beach City Council, March 21, 2023 (part 1 of 3)

C-8 Correspondence – Cynthia Elkins

From: Cynthia Elkins [mailto:[email protected]] Sent: Tuesday, March 21, 2023 3:26 PM
To: CityClerk <[email protected]>
Subject: CBD Sources, Part 2.1

-EXTERNAL-

Please see the attached references in support of the Center for Biological Diversity’s comments to the City Council regarding the Long Beach Unit Annual Plan and Program Plan.

Thank you,
Cynthia Elkins

Cynthia Elkins, Paralegal
Center for Biological Diversity
https://www.biologicaldiversity.org

This email may contain material that is confidential, privileged and/or attorney work product for the sole use of the intended recipient. Any review, reliance or distribution by others or forwarding without express permission is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies.

Vol.:(0123456789)1 3
Bulletin of Environmental Contamination and Toxicology
https://doi.org/10.1007/s00128-021-03176-w
Red Blood Cell Cytotoxicity Associated to Heavy Metals
and Hydrocarbons Exposure in Flounder Fish from Two Regions of the Gulf of Mexico
Juan Pablo Ek‑Huchim1 · Flor Árcega‑Cabrera2 · Ana Luisa May‑Tec1 · Monica Améndola‑Pimenta1 · Víctor Ceja‑Moreno1 · Rossanna Rodríguez‑Canul1
Received: 30 August 2020 / Accepted: 8 March 2021
© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2021 Abstract
In this study, the genotoxic effect of contaminants was assessed through detection of DNA damage using the micronucleus (MNs) test in erythrocytes from 149 flounder fish collected in two regions of the Gulf of Mexico (GoM). The frequency of microcytes (MCs) was also evaluated in the same group of fish collected from the Perdido Foldbelt (PF) and the Yucatan Platform (YP). The MCs frequency was different among locations of the YP (p = 0.011), while MNs frequency varied among locations of PF (p = 0.024). MCs and MNs values correlated with heavy metals from fish muscle, fish species and localities.

Mean number, prevalence, and intensity of MCs and MNs correlated with Al, PAHs, depth, and locality. MNs frequency showed a species-specific association (p = 0.004). MNs and MCs were associated with heavy metals and PAHs from fish muscle and sediments, and the MNs frequency was species dependent.

Keywords Micronuclei · Flounder · Perdido Foldbelt · Yucatan Platform · Gulf of Mexico Crude oil is one of the most widespread pollutant released into the marine environment causing a wide range of bio- logical effects in native species (Bejarano 2018). In the Gulf of Mexico (GoM) there is always a constant menace of oil spill events because crude oil production activities are very important in the region (Allan et al. 2012; Ward and Tunnell 2017). In 2010, around 4.4 × 106 oil barrels were released into the sea for 87 days in the Deepwater Horizon oil spill blowout (Perez et al. 2017). Offshore fish was used to detect the accumulation of polycyclic aromatic hydrocar- bons (PAHs) after the DWH disaster (Murawski et al. 2020).

Flounder fish have been used as bioindicators of habi - tat disturbance because they are in direct contact with the marine sediments (Bolognesi et al. 2006; Conti and
Iacobucci 2008; Holt and Miller 2010). And some compo-
nents of oil are highly persistent (Gregson et al. 2021). Sedi- ments act as sinkholes for hydrocarbons, heavy metals, and other contaminants. These substances become bioavailable to flatfish and are accumulated in their tissues, altering their physiology and reproduction (Kirby et al. 2000; van der Oost et al. 2003; Holt and Miller 2010; Rahmanpour et al. 2016; Yu et al. 2019).

The effect of oil pollutants can be assessed by in vivo and in vitro assays where cellular and molecular biomarker responses are implemented as indicators of environmental disturbances (Gold-Bouchot et al. 2017; Praveen Kumar
et al. 2017). The presence of abnormal cells in blood smears of fish are useful to detect chromosomic damage produced by a wide range of toxic compounds, specifically by detect- ing binucleated or polynucleated cells containing micronu- cleus (MNs) (Ayanda et al. 2018). The MNs are extranu-
clear bodies that contain damaged chromosome fragments
and/or whole chromosomes that were not incorporated into the nucleus after cell division. While microcytes (MCs) are small mature erythrocytes characterized by having a smaller diameter when compared to normal erythrocytes
and their presence has been associated to a deficiency of hemoglobin formation linked to anemia and malnourishment * Rossanna Rodríguez-Canul
[email protected]
1 Departamento de Recursos del Mar, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico
Nacional - Unidad Mérida, Km. 6 Antigua Carretera a
Progreso, CORDEMEX, CP 97310 Mérida, Yucatán, Mexico
2 Unidad de Química Sisal, Facultad de Química, Universidad Nacional Autónoma de México, Puerto de Abrigo S/N,
97356 Sisal, Yucatán, Mexico
Bulletin of Environmental Contamination and Toxicology
1 3
(Alkaladi et al. 2015). The MNs assay are biomarkers used to detect chromosomic damage induced by a variety of gen- otoxic agents (Sommer et al. 2020). Fish challenged with Cd showed a time-dependent increase in the frequency of MNs and nuclear abnormalities that had high correlation with cytoplasmic cell alterations including MCs (Jindal and Verma 2015).

The objectives of this study were to report the presence of MNs and MCs in seven species of fish flounder from two areas of the GoM as well as to associate these values with oil pollutants from sediments and fish muscle.

Methods and Materials
A permit for collection (PPF/DGOPA-070/16) was issued
by Comisión Nacional de Acuacultura y Pesca. Flounder
fish were collected from two areas of the GoM; 41 fish from eight locations (4 to 6 fish per location) from the Perdido Foldbelt (PF). Sampling was done aboard the oceanographic cruise “Justo Sierra”-UNAM using benthic sled trawlers
with 2.40 m of width, 0.90 m of height, 5 m of coded large and mesh size of 0.0254 m. Trawling of approximately one mile was performed at depths of 44 to 107 m between the 12th to 19th in May 2016. In the Yucatan Platform (YP), 108 fishes were collected using a boat from the commercial shrimp fleet implemented with net shrimp trawls of 18.3 m and 0.034 m of mesh size. Sampling was done on two occa- sions: In 2015 (November 17th to 18th) five locations were surveyed and in 2016 (April 13th to 16th), 13 locations were surveyed. In both cases four to 10 organisms per location were collected in trawlers of approximately one mile done at depths of 40 to 200 m (Fig. 1) (Supplementary Table 1).

After capture, ≈ 20 µL of blood was collected from the
caudal vein of each fish using a hypodermic syringe and dropped on glass-slides to perform two blood smears from each fish. Smears were air dried and fixed in absolute metha- nol (Hycel®) for 10 min (Al-Sabti and Metcalfe 1995). Sub- sequently, fishes were euthanized using a sharp scalpel on the fish head. After that, they were dissected, and their sex was identified by visual inspection. Muscle tissue was col- lected above the lateral line from both sides of the fish avoid- ing the abdominal cavity. Muscle samples were stored at − 20°C for pollutants analyses: PAHs (polycyclic aromatic hydrocarbons) and heavy metals (V, Ni, Cd and Pb). Also, approximately 200 g of sediments from nine locations (G34, H39, I43, J48, L59, O73, P78, P79 and P80) from the YP
and from each location of the PF (B1, B2, C1, C2, D1, D2, F1 and F2) were collected for contaminant (PAHs, Al, V, Ni, Cd and Pb) analyses. For heavy metals quantifications, sediments samples were placed in plastic bags previously washed with a 1 M HNO3 (Sigma-Aldrich pure grade) solu- tion and deionized water, while for PAHs quantification, they were placed in glass containers previously washed with hexane and acetone (both Sigma-Aldrich chromatographic
grade). Both samples were kept at 4ºC until further analysis.

For the MNs and MCs assay, glass slides were stained
with 10% Giemsa solution for 8 min, air dried, and then analysed under bright-field microscopes Olympus BX51 at 100× (Baršiene et al. 2004). The MNs and MCs were scored from 3000 mature erythrocytes analysed in each sample.

MNs were identified as small nuclei separated from the main nucleus. MCs were identified from normal erythrocytes by having sizes less than one-third of the normal erythrocyte.

Results were expressed as frequency (MNs/3000 mature
erythrocytes and MCs/3000 mature erythrocytes), mean
value (an average of n numbers computed by adding some
Fig. 1 Sampling locations at the
Perdido Foldbelt (PF) and the
Yucatan Platform (YP)

Bulletin of Environmental Contamination and Toxicology
1 3
function of the numbers and dividing by some function of n), prevalence (%) (the number of organisms with MNs or MCs, divided by the total number of organisms in the sam- ple), and mean intensity (the mean number of MNs or MCs found in infected hosts in a particular population (see Jindal and Verma 2015).

PAHs concentration in muscle was measured in the
dry-freeze tissue following the procedures described by MacLeod et al. (1985) and Wade et al. (1988), and in the dry-freeze sediments following Wade et al. ( 1988). Previ- ous to column chromatographic extraction, samples were
fortified using a surrogate solution of deuterated PAHs (1–3 dimethyl-2 nitrobenzene; acenaphthene δ10, phenanthrene δ10, pyrene δ10, triphenyl phosphate, chrysene δ10 and
perylene δ10 from UltraScientific). Detection limits for PAHs ranged from 0.0152 (benzo[a]anthracene) to 0.4039
(benzo[a]pyrene) and all recovery percentages were above 60%. Compounds were identified and quantified using a
Clarus 500 Perkin Elmer gas chromatographer coupled to
a mass spectrometer detector by the full scan and the ion selected methods (Wang et al. 1994).

For heavy metals analysis, samples were acid-digested
(MARS 6-CEM, EPA method 3052) with nitric acid trace
metal grade. Cd, Ni, V and Pb quantification was done using an ICP-MS iCAP Q Thermo Scientific using the ions 51V,
60Ni, 112Cd and 208Pb. Multielement solutions in several concentrations were prepared from a multistandard solution according to manufacturer instructions. PACS3 and MESS4 (National Research Council Canada) certified reference
material was used to determine precision and accuracy of the analysis. Recovery percentages (RP) were 89.5% for 51V, 86% for 60Ni, 111% for 112Cd, and 118% for 208Pb; the coef- ficient of variation (CV) for V = 20.4%, for Ni = 21.1%, for Cd = 23.7% and for Pb = 24.5% in PACS3. In CRM MESS4,
RP were 83% for 51 V, 81% for 60Ni, 95% for 112Cd, and
112% for 208Pb with a CV of 15.2% for V, for Ni = 22.1%,

8.9% for Cd and for Pb = 22.5%. Detection limits (DL) were

0.0043 µg g−1 for V, 0.0049 µg g−1 for Ni, 0.0039 µg g−1 for Cd, and 0.0053 µg g−1 for Pb, calculated as three times the standard deviation of the measured concentrations of 12 blanks.

The data mapping of all locations was geopositioned with Ocean Data View software version 4.7.9. The variability of MNs and MCs frequencies between localities and fish
species were compared with Fisher´s exact test using the Statistica 8.0 software. The association of variables like frequency, mean number, prevalence and intensity of MNs and MCs with sex, fish species, depth and pollutants (PAHs, heavy metals) from fish tissues and sediments were estab- lished using the generalised additive models for location of scale and shape (GAMLSS) (Rigby and Stasinopoulos
2005). Previously, the multicollinearity of variables was evaluated through a variance inflation factor index (VIF) and Spearman’s correlation, for which the usdm package of R was used (Naimi et al. 2014). To decide which variables were discarded, a threshold of VIF < 4 was established and considered in the GAMLSS analysis (Zuur et al. 2010). The Akaike information criterion (AIC) value in the model set- ting GAMLSS package in R was used to fit the models. The best statistical model was selected by performing a forward procedure using the stepGAIC (generalised Akaike infor - mation criterion) function in the GAMLSS package, as this assessed the contribution of each variable and their combi- nations in the final model through an iterative process. This function chooses the best model based on the lowest AIC value. In addition, the goodness of fit of each model was evaluated through the explained deviance (ED), expressed as a percentage (Rigby and Stasinopoulos 2005). Finally, similitude of mean MNs for the species was tested with
MVSP 3.1 software.

Results and Discussion
This study represents the first approach of using MNs and MCs from flounder fish collected from the YP and PF of
the GoM. The values of MNs and MCs were associated
with data of pollutants obtained from fish muscle and sedi- ments. Fish collected from location C1 of PF were the most affected. Three to nine MNs/fish were observed, 100% of prevalence and mean intensity of 5. Also 60% of sampled fish harbored MCs. The location M63 from YP was the least affected because MNs were not detected there (Table 1).

Likewise, we found significant differences in MCs frequen- cies between locations in the YP (F17;108 = 32.952; p = 0.011) but not in locations from the PF (F7;41 = 0.976; p = 0.995).

No significant differences of MNs frequencies were found among locations from the YP (F17;108 = 24.939; p = 0.096), but significant differences were found in locations from the PF (F7;41 = 16.17; p = 0.024). MNs are useful biomarkers associated to genotoxicity (Jindal and Verma 2015; Shah et al. 2020), and the MCs are more related to health status of fish, but in controlled studies the frequency of MCs showed a high time-dependent correlation to the frequency of MNs (Jindal and Verma 2015). Based in the results of this study, we could speculate that MCs can be also useful biomark - ers, but this topic needs further considerations in laboratory and field studies. For instance, MNs are used in monitoring studies and the variation on their frequencies is associated with anthropogenic pressure and pollution like the presence of heavy metals in each location (Rebok et al. 2017). Our statistical analysis suggested that MNs and MCs frequencies could be subjected to the environmental condition of locali- ties sampled, in special, because the PF areas are used for petroleum exploration and exploitation.

Bulletin of Environmental Contamination and Toxicology
1 3
Table 1 MNs and MCs values
from flounder fish collected in
the YP and PF
*,**p < 0.001
Cruise Location N Mean ± S.D Range Prevalence (%) Mean inten- sity
MNs MCs MNs MCs MNs MCs MNs MCs
YP A3 5 2.4 ± 2.7 0.6 ± 0.55* 0–7 0–1 80 60 3 1
YP A4 5 0.4 ± 0.55 0 0–1 0 40 0 1 0
YP A5 4 2.25 ± 1.71 0 0–4 0 75 0 3 0
YP B8 5 1.8 ± 1.79 0 0–4 0 60 0 3 0
YP F29 5 1.8 ± 2.05 0.2 ± 0.45* 0–4 0–1 60 20 3 1
YP G34 10 0.3 ± 0.67 2.8 ± 5.27* 0–2 0–15 20 50 1.5 5.6 YP G35 10 0.3 ± 0.48 2 ± 3.27* 0–1 0–9 30 50 1 4
YP H39 5 0.8 ± 1.79 0.4 ± 0.89* 0–4 0–2 20 20 4 2
YP H40 2 1 ± 0 2 ± 1.41* 1 1–3 100 100 1 2
YP I43 5 0.6 ± 1.34 3 ± 3* 0–3 0–8 20 80 3 3.75
YP J48 5 1 ± 1.73 0.6 ± 0.55* 0–4 0–1 40 60 2.5 1
YP L59 5 0.4 ± 0.55 0 0–1 0 40 0 1 0
YP M63 5 0 0.6 ± 1.34* 0 0–3 0 20 0 3
YP O73 10 0.1 ± 0.32 0.7 ± 1.34* 0–1 0–4 10 30 1 2.33
YP O75 7 0.14 ± 0.38 0.71 ± 1.11* 0–1 0–3 14.29 42.86 1 1.67 YP P78 10 0.7 ± 0.82 0.2 ± 0.63* 0–2 0–2 50 10 1.4 2
YP P79 5 0.4 ± 0.89 1.8 ± 1.92* 0–2 0–5 20 80 2 2.25
YP P80 5 0.6 ± 1.34 0.8 ± 0.84* 0–3 0–2 20 60 3 1.33
PF B1 5 0.4 ± 0.89** 2.8 ± 3.11 0–2 0–7 20 60 2 4.67
PF B2 5 0.8 ± 0.84** 1.2 ± 1.79 0–2 0–4 60 40 1.33 3
PF C1 5 5 ± 2.35** 1.6 ± 1.82 3–9 0–4 100 60 5 2.67
PF C2 5 1.4 ± 1.14** 0.6 ± 0.89 0–3 0–2 80 40 1.75 1.5
PF D1 6 0.83 ± 1.17** 0.83 ± 0.98 0–3 0–2 50 50 1.67 1.67 PF D2 4 0.75 ± 1.5** 0.75 ± 0.96 0–3 0–2 25 50 3 1.5
PF F1 6 0.33 ± 0.52** 2.17 ± 3.49 0–1 0–9 33.33 50 1 4.33 PF F2 5 2.2 ± 1.3** 0.8 ± 1.3 1–4 0–3 100 40 2.2 2
Table 2 Metals and PAHs concentration (µg kg−1) detected in flounder fish tissue (FT) and in the sediment (Sed) from locations of the YP and the PF
Sample Pollutants YP PF
Mean ± S.D Range Mean ± S.D Range
FT V 30.11 ± 30.55 0–192.9 173.41 ± 144.16 19.34–591.32 FT Ni 327.81 ± 435.58 0–2354.63 799.97 ± 1143.64 70.39–7399.06 FT Cd 8.44 ± 18.04 0–96.82 4.97 ± 13.83 0–89.2
FT Pb 21.62 ± 70.99 0–496.32 2070 ± 3044.53 0–15,253.52 FT PAHs 2248.14 ± 2153.39 2.11–14,324.99 124.5 ± 124.23 2.87–486.97 Sed V 530.59 ± 419.62 0–1279.67 114,732.79 ± 37,732.37 72,631.88–164,299.22 Sed Ni 1124.04 ± 808.16 289.22–2699.98 23,657.21 ± 6750.1 15,442.04–31,847.44 Sed Cd 217.32 ± 36.5 173.55–273.79 99.53 ± 65.74 34.43–211.65 Sed Pb 530.93 ± 332.98 14.86–950.43 20,383.63 ± 4163.1 16,447.21–27,855.68 Sed Al 259,182.5 ± 247,080 779,752.6–43,388.47 11,828,539.21 ± 9,245,092.95 27,342,167.63–2,751,901.14 Sed PAHs 18.59 ± 15.72 0.41–42.53 82.16 ± 60.38 2.02–195.61 Bulletin of Environmental Contamination and Toxicology
1 3
Heavy metal values detected herein in fish muscle (except for Cd) were higher in the PF than in the YP, however PAHs values were higher in the YP than in PF (Table 2). Our data values differ with previous reports in the GoM. Dur - ing 2012–2014 the muscle tissues of flounder fish Syacium gunteri presented lower values of heavy metals and PAHs in YP than in PF (Quintanilla-Mena et al. 2019). Whereas in 2016, higher PAHs concentrations were detected in tis- sues of the fish Lopholatilus chamaeleonticeps from the YP than the ones from the PF (Snyder et al. 2020). Probably the higher values of PAHs and heavy metals found in PF were related to remains of the Macondo oil spill occurred in 2010.

Fish have a high capacity to metabolize PAHs through a
well-developed enzymatic system (Baali et al. 2016), thus, the PAHs values decrease in fish muscle. Nevertheless, the higher values observed in this study in the YP, could be related to bioaccumulation of contaminants from different sources.

In sediments the heavy metals (except for Cd) and PAHs
concentration were higher in PF than in YP (Table 2). PAHs concentration for the YP (18.59 ± 15.72 µg kg−1) and the PF (82.16 ± 60.38 µg kg−1) are considered low according to the classification suggested by Recabarren-Villalón et al. (2019) (PAHs low values from 10 to 100 µg kg−1). The vari- ations of contaminants levels in sediments between YP and PF could be reflecting remains of contaminants from the oil spill occurred in 2010 in the northern GoM (McNutt et al. 2012) although, local inputs such as extraction, production, and transport of petroleum, among others (Murawski and
Hogarth 2013), and contaminant transport related with the hydrology and the hydrodynamics, could also be contribut- ing to the contaminant load (Botello et al. 2015).

The GAMLSS models of MCs and MNs frequency cor -
related with heavy metals from fish muscle, fish species and the locality, with a 20.37% and 25.15% contribution to the explained deviance, respectively (Table 3). Heavy metals are bioaccumulated in the muscle of fish and it is widely known that Cd, V, Pb and Ni induce the formation of MNs and MCs and that the values are different between species (Singh et al. 2019; Shah et al. 2020).

The variability of metals levels found in fish tissue can be subjected to feeding habits, habitats (location) and behaviour of species (Ergene et al. 2007). In this sense, our results indicate that the MNs and MCs have a multifac- torial induction and can be closely related to the biology of the species. The MNs and MCs prevalence, intensity
and mean values correlated with Al, PAHs, depth, and
locality (31.08%, 59.13% and 33.19% explained deviance
to MNs, and 43.22%, 60.45% and 76.37% to MCs respec-
tively) (Table 3). The contaminants detected in sediments from this study could persist for decades in the subsurface layers and organisms could bioaccumulate and incorpo -
rate them into their food chains, increasing the risk for humans through fish and seafood consumption (Bianchini
and Morrissey 2018). Likewise, the PAHs and heavy met-
als mutagenicity affect directly on DNA damage, and
also induce MCs formation through cytoplasmic altera-
tions (Shah et al. 2020). PAHs are considered the most
toxic components of crude oil and have genotoxic effects including DNA damage and DNA mutation (Santana et al.
2018). The exposure of fish to PAHs of oil-contaminated sediment can cause severe adverse effects like metabolic changes, energy imbalance, alterations in organs structure, altered intestinal microbiome structures and increased
mortality (Brown-Peterson et al. 2015). Our results sug- gest that the variation of PAHs and heavy metals in the location samples at different depths are important factors in the variation of the prevalence, mean and intensity of the MNs and MCs because they are associated with the
habitat and fish behaviour (Ergene et al. 2007).

Table 3 GAMLSS model
AIC Akaike information criterion, cs cubic spline smooth function, df degrees of freedom, GD global devi- ance, FD family distribution, P p value, %ED percent of explained deviance, FMNs frequency of MNs, PMNs prevalence of MNs, IMN intensity of MNs, MMN mean of MNs, FMCs frequency of MCs, PMCs prevalence of MCs, IMC intensity of MCs, MMC mean of MCs, Species fish species, Loc localities, PO Poisson distribution, NO Normal distribution, GU Gumbel distribution *p < 0.001
Model Df GD ED (%) AIC FD
FMNs ~ cs(Ni) + cs(Pb) + cs(Species) + cs(Loc)* 17 337.89 25.15 371.90 PO FMCs ~ cs(Ni) + cs(Pb) + cs(V) + cs(Cd) + cs(Species
) + cs(Loc)*
25 516.71 20.37 568.71 NO
PMNs ~ cs(Al) + cs(PAHs) + cs(Depth) + cs(Loc)* 17 110.95 31.08 146.95 NO IMN ~ cs(Al) + cs(PAHs) + cs(Depth)* 14 23.64 59.13 51.64 GU MMN ~ cs(PAHs) + cs(Depth)* 10 52.26 33.19 72.26 NO
PMCs ~ cs(PAHs) + cs(Depth) + cs(Loc)* 13 175.41 43.22 201.41 PO IMC ~ cs(PAHs) + cs(Depth) + cs(Loc)* 13 23.51 60.45 51.50 NO MMC ~ cs(Depth) + cs(Loc)* 10 11.83 76.37 31.83 GU
Bulletin of Environmental Contamination and Toxicology
1 3
From the 149 flounders collected we detected 7 spe-
cies: Syacium papillosum (n = 81), Cyclopsetta chittendeni (n = 18), Cyclopsetta fimbriata (n = 11), Syacium micru- rum (n = 4), Ancyclopsetta dilecta (n = 8), Syacium gunteri (n = 22), and Trichopsetta ventralis (n = 5). In all species MNs were detected (range = 0–9 MNs per fish), as well as MCs (range = 0–15 MCs per fish), but the highest number of MNs was found in C. chittendeni (F6;149 = 18.99; p = 0.004).

In this sense, fish response to xenobiotics as the PAHs dif- fers among the species and stages (Recabarren-Villalón et al. 2019). In contrast, the MCs frequency variation was not sig- nificant for the different species (F6;149 = 5.23; p = 0.515).

The MVPS analysis showed 45.68% of similitude of the
mean MNs among S. papillosum and C. chittendeni. These
results might indicate different susceptibility among spe- cies. Therefore, the selection of sentinel species to assess xenobiotics impact in aquatic environments is a key factor that needs to be evaluated deeply to obtain more accurate information. The presence of environmental contaminants has different accumulation rates that depend on their type, lifetime, and toxicity.

In conclusion, this study represents the first effort to evaluate the presence of MNs and MC in flounders from
two important areas of the GoM. Their values were related to PAHs and heavy metals exposition and showed a negative association to health or fitness of fish. MNs and MCs fre - quencies were more evident in the PF than in the YP. PAHs found in fish muscle were higher than the values found in sediments. MNs frequency showed a species-specific associ- ation being C. chittendeni the most affected organism. Also, we consider that MNs and MCs inductions are multifacto- rial with a probable relevant influence of the fish biology.

Our results support the potential use of MNs and MCs as biomarkers in environmental pollution studies.

Supplementary Information The online version contains supplemen- tary material available at https:// doi. org/ 10. 1007/ s00128- 021- 03176-w.

Acknowledgements Special thanks are conveyed to the personnel of the laboratory of Geochemistry (CINVESTAV-Unidad Merida) for pro- cessing samples. Research funded by the National Council of Science and Technology of Mexico – Mexican Ministry of Energy – Hydro- carbon Trust, project 201441. This is a contribution of the Gulf of Mexico Research Consortium (CIGoM) and PEMEX. We acknowledge PEMEX´s specific request to the Hydrocarbon Fund to address the environmental effects of oil spills in the Gulf of Mexico. The authors are grateful to the comments of the anonymous reviewers.

References
Alkaladi A, El-Deen NAMN, Afifi M, Zinadah OAA (2015) Hema- tological and biochemical investigations on the effect of vitamin E and C on Oreochromis niloticus exposed to zinc oxide nano- particles. Saudi J Biol Sci 22:556–563. https:// doi. org/ 10. 1016/j. sjbs. 2015. 02. 012
Allan SE, Smith BW, Anderson KA (2012) Impact of the Deepwater Horizon oil spill on bioavailable polycyclic aromatic hydrocar - bons in Gulf of Mexico coastal waters. Environ Sci Technol 46(4):2033–2039. https:// doi. org/ 10. 1021/ es202 942q Al-Sabti K, Metcalfe CD (1995) Fish micronuclei for assessing geno- toxicity in water. Mutat Res Toxicol 343:121–135. https:// doi. org/ 10. 1016/ 0165- 1218(95) 90078-0
Ayanda IO, Yang M, Yu Z, Zha J (2018) Cytotoxic and genotoxic effects of perfluorododecanoic acid (PFDoA) in Japanese medaka. Knowl Manag Aquat Ecosyst. https:// doi. org/ 10. 1051/ kmae/ 20170 58
Baali A, Kammann U, Hanel R et al (2016) Bile metabolites of poly - cyclic aromatic hydrocarbons (PAHs) in three species of fish from Morocco. Environ Sci Eur 28:25. https:// doi. org/ 10. 1186/ s12302- 016- 0093-6
Baršiene J, Lazutka J, Šyvokiene J et al (2004) Analysis of micro- nuclei in blue mussels and fish from the Baltic and North Seas.

Environ Toxicol 19:365–371. https:// doi. org/ 10. 1002/ tox. 20031 Bejarano AC (2018) Critical review and analysis of aquatic tox- icity data on oil spill dispersants. Environ Toxicol Chem 37(12):2989–3001. https:// doi. org/ 10. 1002/ etc. 4254 Bianchini K, Morrissey CA (2018) Assessment of shorebird migra- tory fueling physiology and departure timing in relation to polycyclic aromatic hydrocarbon contamination in the Gulf of Mexico. Environ Sci Technol 52:13562–13573. https:// doi. org/

10. 1021/ acs. est. 8b045 71
Bolognesi C, Perrone E, Roggieri P, Sciutto A (2006) Bioindicators in monitoring long term genotoxic impact of oil spill: Haven case study. Mar Environ Res 62:S287–S291. https:// doi. org/ 10. 1016/j. maren vres. 2006. 04. 047
Botello AV, Soto LA, Ponce-Velez G, Villanueva-F S (2015) Base- line for PAHs and metals in NW Gulf of Mexico related to the Deepwater Horizon oil spill. Estuar Coast Shelf Sci 156:124– 133. https:// doi. org/ 10. 1016/j. ecss. 2014. 11. 010 Brown-Peterson NJ, Krasnec M, Takeshita R et al (2015) A multiple endpoint analysis of the effects of chronic exposure to sediment contaminated with Deepwater Horizon oil on juvenile South- ern flounder and their associated microbiomes. Aquat Toxicol 165:197–209. https:// doi. org/ 10. 1016/j. aquat ox. 2015. 06. 001 Conti ME, Iacobucci M (2008) Marine organisms as biomonitors. .

WIT Transact State-of-the-art Sci Eng 30:81–110. https:// doi. org/ 10. 2495/ 978-1- 84564- 002-6/ 04
Ergene S, Cavas T, Celik A et al (2007) Monitoring of nuclear abnor - malities in peripheral erythrocytes of three fish species from the Goksu Delta (Turkey): genotoxic damage in relation to water pollution. Ecotoxicology 16:385–391. https:// doi. org/ 10. 1007/ s10646- 007- 0142-4
Gold-Bouchot G, Rubio-Piña J, Montero-Muñoz J et al (2017) Pol- lutants and biomarker responses in two reef fish species (Hae- mulon aurolineatum and Ocyurus chrysurus) in the Southern Gulf of Mexico. Mar Pollut Bull 116:249–257. https:// doi. org/

10. 1016/j. marpo lbul. 2016. 12. 073
Gregson BH, McKew BA, Holland RD, Nedwed TJ, Prince RC, McGenity TJ (2021) Marine oil snow, a microbial perspective.

Front Mar Sci 8:619484. https:// doi. org/ 10. 3389/ fmars. 2021. 619484
Holt EA, Miller SW (2010) Bioindicators: using organisms to meas- ure environmental impacts. Nature 3(10):8–13
Jindal R, Verma S (2015) In vivo genotoxicity and cytotoxicity assessment of cadmium chloride in peripheral erythrocytes of Labeo rohita (Hamilton). Ecotoxicol Environ Saf 118:1–10. https:// doi. org/ 10. 1016/j. ecoenv. 2015. 04. 005
Kirby MF, Morris S, Hurst M, Kirby SJ, Neall P, Tylor T, Fagg A (2000) The use of cholinesterase activity in flounder (Plat- ichthys flesus) muscle tissue as a biomarker of neurotoxic Bulletin of Environmental Contamination and Toxicology
1 3
contamination in UK estuaries. Mar Pollut Bull 40(9):780–791. https:// doi. org/ 10. 1016/ S0025- 326X(00) 00069-2
MacLeod WD, Brown DD, Friedman AJ et al (1985) Standard analyti- cal procedures of the NOAA (National Oceanic and Atmospheric Administration) national analytical facility, 1985–1986: extract- able toxic organic compounds, 2nd edn. S. Department of Com- merce, NOAA/NMFS, NOAA Tech Memo NMFS F/NWRC-92
McNutt MK, Chu S, Lubchenco J et al (2012) Applications of science and engineering to quantify and control the Deepwater Horizon oil spill. Proc Natl Acad Sci USA 109:20222–20228. https:// doi. org/ 10. 1073/ pnas. 12143 89109
Murawski SA, Hogarth WT (2013) Enhancing the ocean observing sys- tem to meet restoration challenges in the Gulf of Mexico. Ocean- ography 26(1):10–16. https:// doi. org/ 10. 5670/ ocean og. 2013. 12 Murawski SA, Hollander DJ, Gilbert S, Gracia A (2020) Deep-water oil and gas production in the Gulf of Mexico, and related global trends. In: Murawski SA, Ainsworth C, Gilbert S, Hollander D, Paris CB, Schlüter M et al (eds) Scenarios and responses to future deep oil spills—fighting the next war. Springer, Cham
Naimi B, Hamm NAS, Groen TA et al (2014) Where is positional uncertainty a problem for species distribution modelling? Ecog- raphy 37:191–203
Perez CR, Moye JK, Cacela D et al (2017) Low level exposure to crude oil impacts avian flight performance: The Deepwater Horizon oil spill effect on migratory birds. Ecotoxicol Environ Saf 146:98– 103. https:// doi. org/ 10. 1016/j. ecoenv. 2017. 05. 028 Praveen Kumar MK, Shyama SK, D’Costa A et al (2017) Evaluation of DNA damage induced by gamma radiation in gill and muscle tissues of Cyprinus carpio and their relative sensitivity. Ecotoxi- col Environ Saf 144:166–170. https:// doi. org/ 10. 1016/j. ecoenv. 2017. 06. 022
Quintanilla-Mena M, Gold-Bouchot G, Zapata-Pérez O et al (2019) Biological responses of shoal flounder (Syacium gunteri) to toxic environmental pollutants from the southern Gulf of Mexico. Envi- ron Pollut. https:// doi. org/ 10. 1016/j. envpol. 2019. 113669 Rahmanpour S, Ashtiyani SML, Ghorghani NF (2016) Biomonitoring of heavy metals using bottom fish and crab as bioindicator species, the Arvand River. Toxicol Ind Health 32:1208–1214. https:// doi. org/ 10. 1177/ 07482 33714 554410
Rebok K, Jordanova M, Slavevska-Stamenković V et al (2017) Fre- quencies of erythrocyte nuclear abnormalities and of leucocytes in the fish Barbus peloponnesius correlate with a pollution gradi- ent in the River Bregalnica (Macedonia). Environ Sci Pollut Res 24:10493–10509. https:// doi. org/ 10. 1007/ s11356- 017- 8665-6 Recabarren-Villalón T, Ronda AC, Arias AH (2019) Polycyclic aro- matic hydrocarbons levels and potential biomarkers in a native South American marine fish. Reg Stud Mar Sci 29:100695. https:// doi. org/ 10. 1016/j. rsma. 2019. 100695
Rigby RA, Stasinopoulos DM (2005) Generalized additive mod- els for location, scale and shape. J R Stat Soc Ser C Appl Stat 54:507–554
Santana MS, Sandrini-Neto L, Filipak Neto F et al (2018) Biomarker responses in fish exposed to polycyclic aromatic hydrocarbons (PAHs): systematic review and meta-analysis. Environ Pollut 242:449–461. https:// doi. org/ 10. 1016/j. envpol. 2018. 07. 004 Shah N, Khan A, Ali R, Marimuthu K et al (2020) Monitoring Bio- accumulation (in Gills and Muscle Tissues), Hematology, and Genotoxic Alteration in Ctenopharyngodon idella Exposed to Selected Heavy Metals. Biomed Res Int. https:// doi. org/ 10. 1155/ 2020/ 61852 31
Singh M, Khan H, Verma Y, Rana SVS (2019) Distinctive fingerprints of genotoxicity induced by As, Cr, Cd, and Ni in a freshwater fish.

Environ Sci Pollut Res 26:19445–19452. https:// doi. org/ 10. 1007/ s11356- 019- 05274-z
Snyder SM, Olin JA, Pulster EL, Murawski SA (2020) Spatial contrasts in hepatic and biliary PAHs in Tilefish (Lopholatilus chamaele- onticeps) throughout the Gulf of Mexico, with comparison to the Northwest Atlantic. Environ Pollut 258:113775. https:// doi. org/

10. 1016/j. envpol. 2019. 113775
Sommer S, Buraczewska I, Kruszewski M (2020) Micronucleus assay:
the state of art, and future directions. Int J Mol Sci 21:1–19. https:// doi. org/ 10. 3390/ ijms2 10415 34
Van der Oost R, Beyer J, Vermeulen NPE (2003) Fish bioaccumula - tion and biomarkers in environmental risk assessment: a review.

Environ Toxicol Pharmacol 13(2):57–149. https:// doi. org/ 10. 1016/ S1382- 6689(02) 00126-6
Wade TL, Atlas EL, Brooks JM et al (1988) NOAA Gulf of Mexico status and trends program: Trace organic contaminant distribution in sediments and oysters. Estuaries 11:171–179. https:// doi. org/

10. 2307/ 13519 69
Wang Z, Fingas M, Li K (1994) Fractionation of a light crude oil and identification and quantitation of aliphatic, aromatic, and bio - marker compounds by GC-FID and GC-MS, part I. J Chromatogr Sci 32:361–366. https:// doi. org/ 10. 1093/ chrom sci/ 32.9. 361 Ward CH, Tunnell JW (2017) Habitats and Biota of the Gulf of Mex- ico: An Overview. In: Ward C (ed) Habitats and biota of the Gulf of Mexico: before the Deepwater Horizon oil spill. Springer, New York, pp 1–54
Yu Z, Lin Q, Gu Y, Du F, Wang X, Shi F, Ke Ch, Xiang M, Yu Y (2019) Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in wild marine fish from the coastal waters of the northern South China Sea: risk assessment for human health. Ecotoxicol Environ Saf 180:742–748. https:// doi. org/ 10. 1016/j. ecoenv. 2019.

05. 065
Zuur AF, Ieno EN, Elphick CS (2010) A protocol for data exploration to avoid common statistical problems. Methods Ecol Evol 1:3–14 Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Injection-Induced Earthquakes
William L. Ellsworth
Background: Human-induced earthquakes have become an important topic of political and scientiﬁ c discussion, owing to the concern that these events may be responsible for widespread damage and an overall increase in seismicity. It has long been known that impoundment of reservoirs, surface and underground mining, withdrawal of ﬂ uids and gas from the subsurface, and injection of ﬂ uids into underground formations are capable of inducing earthquakes. In particular, earthquakes caused by injection have become a focal point, as new drilling and well-completion technologies enable the extraction of oil and gas from previously unproductive formations.

Advances: Microearthquakes (that is, those with magnitudes below 2) ar e routinely produced as part of the hydraulic fracturing (or “fracking”) process used to stimulate the production of oil, but the process as currently practiced appears to pose a low risk of inducing destructive earthquak es.

More than 100,000 wells have been subjected to fracking in recent years, and the largest induced earthquake was magnitude 3.6, which is too small to pose a serious risk. Yet, wastewater disposal by injection into deep wells poses a higher risk, because this practice can induce larger earthquakes.

For example, several of the largest earthquakes in the U.S. midcon tinent in 2011 and 2012 may have been triggered by nearby disposal wells. The largest of these was a magnitude 5.6 even t in central Oklahoma that destroyed 14 homes and injured two people. The mechanism responsible for inducing these events appears to be the well-understood process of weakening a preexisting fault by elevating the ﬂ uid pressure. However, only a small fraction of the more than 30,000 wastewater disposal wells appears to be pr oblematic—typically those that dispose of very lar ge volumes of water and/or communicate pressure perturbations directly into basement faults.

Outlook: Injection-induced earthquakes, such as those that struc k in 2011, clearly con tribute to the seismic hazard. Quantifying their contribution presents difﬁ cult challenges that will require new research into the physics of induced earthquak es and the potential for inducing large-magnitude events. The petroleum industry needs clear r equirements for oper ation, regulators must have a solid scientiﬁ c basis for those r equirements, and the public needs assur ance that the regulations are sufﬁ cient and are being followed. The current regulatory frameworks for wastewater disposal wells were designed to protect potable water sources from contamination and do not address seis- mic safety. One consequence is
that both the quan tity and
timeliness of in formation on
injection volumes and pr es-
sures r eported to r egulatory
agencies are far from ideal for
managing earthquake risk from
injection activities. In addition,
seismic monitoring capabilities
in many of the ar eas in whic h
wastewater injection activities
have increased are not capable
of detecting small earthquak e
activity that may presage larger
seismic events.

ARTICLE OUTLINE
Mechanics of Induced Earthquakes
Earthquakes Induced by Hydraulic Fracturing
Earthquakes Induced by Deep Injection
Lessons from Three Case Studies of Deep,
High-Volume Injection
Other Causes of Induced Earthquakes
Hazard and Risk of Induced Earthquakes
Unknown Knowns
Reducing the Risk of Injection-Induced
Earthquakes

ADDITIONAL RESOURCES
The following resources provide an introduction to
earthquake hazards and risk, the science of induced
earthquakes, and strategies for managing the risk.

C. Nicholson, R. L. Wesson, “Earthquake hazard
associated with deep well injection: A report to the
U.S. Environmental Protection Agency,” U.S. Geol.

Surv. Bull. 1951 (1990); http://pubs.usgs.gov/
bul/1951/report.pdf.

Committee on Induced Seismicity Potential in Energy
Technologies, Induced Seismicity Potential in Energy
Technologies (National Research Council, Washing-
ton, DC, 2012); http://dels.nas.edu/Report/Induced-
Seismicity-Potential-Energy-Technologies/13355.

S. Horton, Disposal of hydrofracking waste ﬂ uid by
injection into subsurface aquifers triggers earth-
quake swarm in central Arkansas with potential for
damaging earthquake. Seismol. Res. Lett. 83, 250–
260 (2012). doi:10.1785/gssrl.83.2.250
Tutorial material on probabilistic seismic hazard
analysis (PSHA): www.opensha.org/sites/opensha.
org/ﬁ les/PSHA_Primer_v2_0.pdf
M. D. Zoback, Managing the seismic risk posed by
wastewater disposal. Earth Magazine 57, 38–43
(2012).

Earthquake Science Center, U.S. Geological Survey, Menlo Park, CA 94025, USA.

E-mail: [email protected]
Cumulative number of earthquakes
M > 3
Year
Earthquake count
14000 200 400 600 800 1000 1200
1970 1980 1990 2000 2010
=
Earthquakes with magnitude (M)
≥ 3 in the U.S. midcon tinent,
1967–2012. After decades of a
steady earthquake rate (average of
21 events/year), activity incr eased
starting in 2001 and peaked at 188
earthquak es in 2011. Human-
induced earthquakes are suspected
to be partially r esponsible for the
increase.
12 JULY 2013 VOL 341 SCIENCE www.sciencemag.org 142

REVIEW SUMMARY

READ THE FULL ARTICLE ONLINE
http://dx.doi.org/10.1126/science.1225942
Cite this article as W. L. Ellsworth,
Science 341, 1225942 (2013).

DOI: 10.1126/science.1225942
Published by AAAS
on August 7, 2013www.sciencemag.orgDownloaded from
Injection-Induced Earthquakes
William L. Ellsworth
Earthquakes in unusual locations have become an important topic of discussion in both North America and Europe, owing to the concern that industrial activity could cause damaging earthquakes. It has long been understood that earthquakes can be induced by impoundment of reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into underground formations. Injection-induced earthquakes have, in particular, become a focus of discussion as the application of hydraulic fracturing to tight shale formations is enabling the production of oil and gas from previously unproductive formations.

Earthquakes can be induced as part of the process to stimulate the production from tight shale formations, or by disposal of wastewater associated with stimulation and production. Here, I review recent seismic activity that may be associated with industrial activity, with a focus on the disposal of wastewater by injection in deep wells; assess the scientific understanding of induced earthquakes; and discuss the key scientific challenges to be met for assessing this hazard.

E
arthquakes are expected within tectoni-
cally active regions such as along plate
boundaries or within distributed zones of
deformation. Recent seismic activity across the
coterminous United States, for example, concen-
trates along the plate boundaries of the West
Coast and within the intermountain West (Fig. 1).

Within such actively deforming zones, elastic
strain energy accumulates in the crust, sometimes
for centuries, before being released in earth-
quakes. The potential for earthquakes also exists
within continental interiors, despite very low de-
formation rates (1). This is because shear stress
levels within the interior of plates or near plate
boundaries are commonly found to be near the
strength limit of the crust ( 2). Under these con-
ditions, small perturbations that effect fault sta-
bility can and do trigger earthquakes ( 3–6). For
example, the injection of water under high pres-
sure into impermeable basement rocks beneath
Basel, Switzerland, to devel o pa ne n h a n c e dg e o t h e r - mal system beneath the city induced four moment
magnitude (M
w) 3 earthquakes in 2006 and 2007
(7) (earthquake magnitudes measured using other
scales are denoted byM ). These small earthquakes
led to the abandonment of the project, loss of the
investment, and ongoing litigation over compen-
sation for damage. The extraction of natural gas
from shallow deposits in the Netherlands also
causes earthquakes (8). A recent M 3.4 event near
Loppersum damaged scores of homes in the area,
resulting in large losses for the property owners (9).

Within the central and eastern United States,
the earthquake count has increased dramatically
over the past few years (Fig. 2). More than 300
earthquakes with M ≥ 3o c c u r r e di nt h e3y e a r s from 2010 through 2012, compared with an av-
erage rate of 21 events/year observed from 1967
to 2000. States experiencing elevated levels of
seismic activity included Arkansas, Colorado, New
Mexico, Ohio, Oklahoma, Texas, and Virginia. The
greatest rise in activity occurred in 2011 when 188
M ≥ 3 earthquakes occurred. Although earthquake
REVIEW
Earthquake Science Center, U.S. Geological Survey, Menlo Park, CA 94025, USA.

E-mail: [email protected]
-70
50 45
40 35
30 25
-80-90
Longitude
Latitude
-100-110-120
Fig. 1. Seismicity of the coterminous United States and surrounding re- gions, 2009–2012.Black dots denote seismic events. Only earthquakes withM ≥ 3 are shown; larger symbols denote events withM ≥ 4. Background colors give the probability of peak ground acceleration with a 2% probability of exceedance in 50 years, from the U.S. National Seismic Hazard Map (1). Red,≥ 1g;o r a n g e ,0 . 3 to 1g;y e l l o w ,0 . 1t o0 . 3g; light green, 0.03 to 0.1g;d a r k e rg r e e n ,0 . 0 3t o0 . 1g. www.sciencemag.org SCIENCE VOL 341 12 JULY 2013
1225942-1
on August 7, 2013www.sciencemag.orgDownloaded from
detection improved for M < 3 as the USArray
transportable seismograph array began to pass
through the region starting in 2008 (10), a recent
report on seismicity in the central and eastern
United States found that the probability of missing
M ≥ 3 earthquakes in the region has been near
zero for decades (11). Consequently, the increased
earthquake count represents a temporal change in
earthquake rate. Because the hazard of damaging
ground shaking is fundamentally related to the rate
of earthquake occurrence (1), regions where the rate
increased may be more hazardous than forecast by
the 2008 version of the U.S. National Seismic
Hazard Map (Fig. 1) (1). Understanding why seis-
micity increased and how this increase affects the
hazard have become a priority for the earthquake-
research community.

A number of these recent earthquakes occurred
in areas where specific types of nearby industrial
activities raise the possibility that theseevents were
induced by human activity. Here, I will use the term
“induced”to include both earthquakes triggered
by anthropogenic causes that primarily release
tectonic stress and those that primarily release
stresses created by the industrial activity (4). Un-
derstanding which earthquakes may have been
induced and, if so, how are challenging problems
to solve in the current data-poor environment.

Several examples since 2011 highlight the
difficulty in determining whether earthquakes
were induced by human activity. The M
w 4.0
earthquake on 31 December 2011 in Youngstown,
Ohio, appears to have been induced by injection
of wastewater in a deep Underground Injection
Control (UIC) class II well ( 12). The M
w 4.7
27 February 2011 central Arkansas earthquake
has also been linked to deep injection of waste-
water (13). The M
w 4.4 11 September 2011 earth-
quake near Snyder, Texas, occurred in an oil field
where injection for secondary recovery has been
inducing earthquakes for years (14). The M
w 4.8
10 October 2011 earthquake near Fashing, Texas,
occurred in a region where long-term production
of gas has been linked to earthquake activity (15).

For others, such as theM
w 5.7 6 November 2011
central Oklahoma earthquake (16)o rt h eMw 4.9
17 May 2012 east Texas earthquake (17), where
active wastewater-injection wells are located near
their respective epicenters, the question of natural
versus induced remains an active topic of research.

The potential association between deep waste-
water disposal wells and earthquakes has received
considerable attention due to the association of
this activity with the development of tight shale
formations for gas and petroleum by hydraulic
fracturing, or“fracking” (5). Wells used in the U.S.
petroleum industry to inject fluids are regulated
as UIC class II wells. Approximately 110,000 of
these wells are used for enhanced oil recovery.

In addition, 30,000 class II wells in the United
States are used for wastewater disposal. Of these
wells, most have no detected seismicity within
tens of kilometers, although a few are correlated
with seismicity (18). However, this can be said
with confidence only for earthquakesM
w ≥ 3, as
smaller earthquakes are not routinely reported
in the central and eastern United States. So it is
possible that smaller earthquakes could be more
common in the vicinity of these wells. In Califor-
nia, where the completeness threshold is below
M
w 2, the majority of the 2300 active wastewater-
injection wells are located in regions of low seis-
micity. As with elsewhere in the United States, a
small fraction of the California wastewater wells
coincide with earthquakes, which raises the ques-
tion of what factors distinguish those seismically
active wells from the majority of wells if the
earthquakes and injection activities are related.

Mechanics of Induced Earthquakes
Earthquakes release stored elastic strain energy
when a fault slips. A fault will remain locked as
long as the applied shear stress is less than the
strength of the contact. The failure condition to
initiate rupture is usually expressed in terms of
the effective stresst
crit = m(sn – P)+t o,w h e r et h e
critical shear stresstcrit equals the product of the
coefficient of frictionm and the effective normal
stress given by the difference between the ap-
plied normal stress s
n and the pore pressure P
(3, 19, 20). For almost all rock types, m lies be-
tween 0.6 and 1.0, and the cohesive strength of
the sliding surface,t
o, is negligible under typical
crustal conditions. Increasing the shear stress, re-
ducing the normal stress, and/or elevating the pore
pressure can bring the fault to failure, triggering
the nucleation of the earthquake (Fig. 3). Once ini-
tiated, sliding resistance drops and seismic waves
radiate away, driven by the imbalance between the
elastic stress stored in the surrounding rock mass
and the frictional resistance of the dynamically
weakened sliding surface. Rupture will continue to
propagate, as long as the wave-mediated stress at
the rupture front exceeds the static strength, and
may extend into regions where the ambient stresses
are below the failure threshold.

Rocks fail in tension when the pore pressure
exceeds the sum of the least principal stress, s
3,
and the tensile strength of the rock, forming an
opening-mode fracture that propagates in the
plane normal to s3. The industrial process of hy-
draulic fracturing commonly involves both tensile
and shear failure. Depending on the local stress
state, hydraulically conductive fractures may be
induced to fail in shear beforeP = s

3. A successful
“frac job”may create a fracture network dominated
by pathways created by shear failure (21).

Longitude
Latitude
Cumulative number of earthquakes
M > 3
Year
Earthquake count
1967 through 2012
14000 200 400 600 800 1000 1200
1970 1980 1990 2000 2010
504540353025 105 100 95 90 85
=
Fig. 2. Cumulative count of earthquakes with M ≥ 3 in the central and eastern United States, 1967–2012. The dashed line corresponds to the long-term rate of 21.2 earthquakes/year. ( Inset) Distribution of epicenters in the region considered here. 12 JULY 2013 VOL 341 SCIENCE www.sciencemag.org1225942-2 REVIEW
on August 7, 2013www.sciencemag.orgDownloaded from
Earthquakes are known to be induced by a
wide range of human activities (3–5) that modify
the stress and/or pore pressure (Fig. 3). At present,
with the use of seismological methods, it is not
possible to discriminate between man-made and
natural tectonic earthquakes. Induced earthquakes
sometimes occur at the source of the stress or pres-
sure perturbation; at other times, these events take
place deep below and kilometers away from the
source. When removed from the source, induced
earthquakes typically release stored tectonic stress
on preexisting faults, as do natural earthquakes.

Sometimes induced events occur shortly after the
industrial activity begins, but in other cases they
happen long after it has been under way or even
ceased. Factors that should enhance the probability
of a particular stress or pore-pressure perturbation
inducing earthquakes include the magnitude of
the perturbation, its spatial extent, ambient stress
condition close to the failure condition, and the
presence of faults well oriented for failure in the
tectonic stress field. Hydraulic connection between
the injection zone and faults in the basement may
also favor inducing earthquakes, as the tectonic
shear stress increases with depth in the brittle crust
(2). In addition, the larger the fault, the larger the
magnitude of earthquakes it can host.

Methods for anticipating the time of failure
have long been the “holy grail” of seismology
(22). Though short-term prediction remains an
elusive goal, it has been proposed that critically
loaded faults have enhanced triggering suscep-
tibility to dynamic stresses from distant earth-
quakes (23). Specifically, some but not all of the
sites where fluid-injection–induced earthquakes
are suspected of contributing to the recent in-
crease in seismicity in the midcontinent (Fig. 2)
experienced increased rates of microearthquakes
in the days immediately after three recent great
earthquakes (23).

Earthquakes Induced by Hydraulic Fracturing
The industrial process of hydraulic fracturing
involves the controlled injection of fluid under
pressure to create tensile fractures, thereby in-
creasing the permeability of rock formations. It
has been used for well over half a century to
stimulate the recovery of hydrocarbons. For
many decades, the primary application was to
improve the output of aging oil and gas reser-
voirs. Beginning in the late 1990s, technologies
for extracting natural gas and oil from tight
shale formations led to the development of new
natural gas fields in many parts of the central
and eastern United States, western Canada, and
Europe. Global development of oil and gas from
shale will undoubtedly continue, as the resource
potential is high in many parts of the world.

Extracting hydrocarbons from shale requires
the creation of a network of open fractures con-
nected to the borehole. Horizontal drill holes ex-
tending up to several kilometers within the shale
formation undergo a staged series of hydraulic
fractures, commonly pressurizing a limited section
of the cased well at a time to stimulate the flow
of gas or oil into the well. Each stage involves the
high-pressure injection of water into the formation.

Fracking intentionally induces numerous micro-
earthquakes, the vast majority with M
w <1 .

Several cases have recently been reported in
which earthquakes large enough to be felt but too
small to cause structural damage were associated
directly with fracking. These cases are notable be-
cause of the public concern that they raised, de-
spite maximum magnitudes far too small to cause
structural damage. Investigation of a sequence of
felt events with maximumM 2.9 in south central
Oklahoma revealed a clear temporal correlation
between fracking operations in a nearby well and
the seismic activity (24) .A v a i l a b l ed a t aw e r ei n s u f - ficient to definitely rule out a natural cause due to
the occurrence of some natural seismicity in the
general area. In April and May 2012, a series of
induced earthquakes with maximum M 2.3 oc-
curred near Blackpool, United Kingdom ( 25),
during fracking to develop a shale gas reservoir.

One of the major shale plays in the United
States— the Marcellus Shale of the Appalachian
Basin in Pennsylvania, West Virginia, Ohio, and
New York— lies within a region characterized
by low levels of natural seismic activity (Fig. 1).

The regional seismographic network operated by
Lamont Doherty Earth Observatory (LDEO) sys-
tematically catalogs all earthquakes with M ≥ 2
in Pennsylvania (Fig. 4). Although thousands of
hydraulic fractures were done in Pennsylvania
since major development of the field began in
2005, only six earthquakes withM ≥ 2 were de-
tected by the LDEO network within the footprint
of the Marcellus Shale, the largest of which was
just M 2.3. The largest earthquake in the region
since the development of shale gas happened
across the Ohio border in Y oungstown, where it
was induced by injection (12), much of the fluid
apparently coming from wells in Pennsylvania.

Beginning in 2009, an unusual sequence of
earthquakes was noted in the Horn River Basin of
British Columbia, including 21 events withM
w 3.0
and larger. Only the largest, atMw 3.6, was reported
as felt by workers in this remote area where it did no
damage (26). The investigation into the cause of these
events by the BC Oil and Gas Commission (26)
concluded that the events“were caused by fluid in-
jection during hydraulic fracturing in proximity of
pre-existing faults.”Two of the hydrofrac treatments
were recorded by dense seismometer deployments
at the surface. Precise hypocentral locations showed
that the induced earthquakes occurred on previously
unknown faults located outside of the stimulation
interval that were well oriented for failure in the am- bient stress field. Apparently, fracture pressure was
quickly communicated through hydraulically conduc-
tive pathways and induced slip on critically stressed
faults via reduction of the effective normal stress.

Earthquakes Induced by Deep Injection
There has been a growing realization that the prin-
cipal seismic hazard from injection-induced earth-
quakes comes from those associated with disposal of
wastewater into deep strata or basement formations
(5). Before 2011, the M
w 4.8 event on 9 August
1967 near Denver, Colorado, was the largest event
widely accepted in the scientific community as
having been induced by wastewater injection (5).

The hazard landscape of what is possible has shifted
due to the role that wastewater injection into a
depleted oil field may have played in theM
w 5.7
6 November 2011 central Oklahoma earthquake
(16), although a consensus on its origin has not yet
been reached (27). This earthquake damaged homes
and unreinforced masonry buildings in the epicentral
Changes in solid stress
due to fluid extraction or injection
(poro-thermoelastic effects,
changes in gravitational loading)
Permeable
reservoir/
aquifer
Volume and/or mass change
Permeable
reservoir/aquifer
Direct fluid pressure
effects of injection
(fluid pressure
diffusion)
Increase in pore
pressure along
fault (requires
high-permeability
pathway)
Fault
Fault
Well
Change in loading
conditions on fault
(no direct hydrologic
connection required)
Fig. 3. Schematic diagram of mechanisms for inducing earthquakes. Earthquakes may be in- duced by increasing the pore pressure acting on a fault ( left) or by changing the shear and normal stress acting on the fault ( right). See (4 ).
www.sciencemag.org SCIENCE VOL 341 12 JULY 2013 1225942-3 REVIEW
on August 7, 2013www.sciencemag.orgDownloaded from
area and was felt as far as 1000 km away in
Chicago, Illinois.

The November 2011 central Oklahoma earth-
quake sequence initiated very close to a pair of
wastewater-injection wells where disposal operation
began 18 years earlier (16). No unusual seismicity
was detected in this historically quiet region, where
only a few events of M < 2 were noted, until a
M
w 4.1 earthquake occurred near the wells in early
2010. Aftershocks of this event continued spo-
radically through 2010 and into mid-2011. This
decaying sequence was shattered by a Mw 5.0
earthquake on 5 November 2011, followed 20 hours
later by theM
w 5.7 mainshock. With the initiating
point of the November sequence within 1.5 km of
the injection wells and some earthquake hypocen-
ters at the same depth as injection, the potential for
a causal connection between injection and the earth-
quakes is clear. The long delay between the start of
injection and the earthquakes, however, deviates
from the pattern seen in other documented cases
of injection-induced seismicity, such as the 2011
Youngstown, Ohio, earthquake where there was, at
most, a few months of delay before induced seis-
micity began. In the Oklahoma case, years of injec-
tion may have been needed to raise the pore pressure
above the preproduction level in this depleted
oil field before fault strength was exceeded (16).

Much of the concern about earthquakes and
fracking centers on the injection of wastewater,
composed of flowback fluids and coproduced
formation brine in deep wells, and not on frack-
ing itself. Wastewater disposal appears to have
induced both the 2011 central Arkansas earthquake
(13) and the 2011 Y oungstown, Ohio, earthquake
(12), as mentioned above. Unprecedented levels
of seismicity have also been seen in the Barnett
Shale in north central Texas, where commercial
development of shale gas was pioneered. Since
development began in late 1998, nine
earthquakes ofM ≥ 3 occurred, compared
with none in the preceding 25 years. A
notable sequence occurred in the Dallas–
Fort Worth area from October 2008 through
May 2009. A detailed investigation of this
sequence concluded that the earthquakes
were most probably caused by disposal of
shale gas wastewater in a UIC class II
disposal well at the Dallas/Fort Worth
International Airport (28), although as
with the Oklahoma earthquake, not all
investigators agree that the case is proven
(29). Because routine earthquake report-
ing in the region is incomplete for events
of M < 3, the passage of the USArray
Transportable Array through the region
over an 18 month period in 2009 –2011
made it possible to improve magnitude
completeness toM 1.5 and location accu-
racy by several fold. Epicenters for the
most reliable locations were clustered in
eight groups, all within 3 km of high-rate
(>25,000 m
3/month) wastewater-injection
wells (18). These results suggest that
the injection rate, as well as the total
volume of injection, may be a predictor of seis-
mic potential.

Lessons from Three Case Studies of Deep,
High-Volume Injection
Conclusions about the cause of many of the recent
earthquakes suspected of being induced by injec-
tion are complicated by incomplete information on
the hydrogeology, the initial state of stress and pore
pressure, the pumping history of the well(s), and
where pressure changes are being communicated at
depth. Routine earthquake locations withuncertain-
ties of 5 to 10 km and a high magnitude-detection
threshold are of limited use. Three particularly well-
documented cases of injection-induced seismicity
from Colorado illustrate what can be learned when
more is known about the pre-injection stress state
and seismicity, as well as the injection history.

Rocky Mountain Arsenal
In 1961, a deep injection well was drilled at the
Rocky Mountain Arsenal (RMA) northeast of
Denver, Colorado, to dispose of hazardous chem-
icals produced at this defense plant (30). Within
several months of the start of routine injection in
the 3.6-km-deep well in March 1962, residents of
the northeastern Denver area began to report earth-
quakes, and events registered on two nearby seis-
mic stations. Between the start of injection and
its termination in February 1966, a total of 13 earth-
quakes with body wave magnitudes ( m
b)4a n d
larger occurred. The following year, the three largest
of the Denver earthquakes occurred, including the
M
w 4.8 event on 9 August 1967 that caused minor
structural damage near the epicenter. By this time,
the earthquakes had migrated as far as 10 km from
the injection point (31). Hydrologic modeling showed
that the migrating seismicity would track a critical
pressure front of 3.2 MPa (32). Although declining,
earthquake activity continued for the next two
decades, including am
b 4.3 earthquake on 2 April
1981. The RMA earthquakes demonstrate how the
diffusion of pore pressure within an ancient fault
system can initiate earthquakes many kilometers
from the injection point, delayed by months or
even years after injection ceased.

Rangely
The insights gained from RMA led to the sug-
gestion that earthquakes could be controlled by
modulating the fluid pressure in the fault, ac-
cording to the effective-stress relation (19). In 1969, the U.S. Geological Survey (USGS) began an ex-
periment to test the effective-stress hypothesis in
the Rangely oil field in northwestern Colorado
(20). Water injected into the reservoir under high
pressure had been used to enhance oil production
at Rangely since 1957. The operator, Chevron Oil
Company, gave USGS permission to regulate the
f l u i dp r e s s u r ei nap o r t i o no ft h ef i e l dt h a tw a s known to be seismically active. Laboratory mea-
surements of the coefficient of friction on core
s a m p l e so ft h er e s e r v o i rr o c k sa n di ns i t ud e t e r - mination of the state of stress led to the prediction
that a critical fluid pressure of 25.7 MPa would be
required to induce earthquakes. Two cycles of fluid
injection and withdrawal were conducted between
1969 and 1973. When the pressure in a monitoring
well exceeded the target pressure, earthquake ac-
tivity increased; when pressure was below the
threshold, earthquake activity decreased. In partic-
ular, the earthquake activity ceased within 1 day of
the start of backflow in May 1973, providing strong
evidence that the rate of seismicity could be con-
trolled by adjusting the pore pressure at the depth
where earthquakes initiate, if stress conditions and
the strength of the faulted rock mass were known.

The rapid response of seismicity at the onset of
backflow also emphasized the importance
of understanding the geohydrology and, in
particular, the importance of hydraulically
conductive faults and fractures for trans-
mitting pore pressure within the system.

Paradox Valley
An ongoing fluid-injection project has been
under way since 1996 in Paradox V alley in
southwestern Colorado, where the saline
shallow water table is being suppressed
by pumping to prevent salt from entering
the Dolores River as it crossed the valley
and, eventually, the Colorado River further
downstream (33). In its natural state, the
Dolores River picks up salt from the
groundwater as it crosses Paradox V alley.

After extensive study of alternatives, the
U.S. Bureau of Reclamation determined
that high-pressure injection of brine into
a deep disposal well (UIC class V) pro-
vided the best method for reducing the
salinity of the Dolores River. Injection oc-
curs in a tight, but highly fractured dolo-
mitic limestone with a fracture-dominated
porosity of less than 6% located 4.3 km

PENNSYLVANIAPENNSYLVANIA

PENNSYLVA NIA

PENNSYLVA NIA
YLVA

YLVAPENNSYLVANIA

NEW YORK
OHIO

WEST VIRGINIA DELAWARE

NEW YORK
OHIO

WEST VIRGINIA DELAWARE

NEW YORK
OHIO

WEST VIRGINIA DELAWARE

NEW Y ORK

NEW YORK

NEW YORKNEW YORK
OHIO
OHI O
OHI O

OHI OOHIO

WEST VIRGINI A

WEST VIRGINIA

WEST VIRGINIAWEST VIRGINIA
RE
RE
RE
RE

DEL AWAR

DEL WAR

DEL AWAR

DEL AWAR
R
R
R

RDELAWARE
42°30'N
40°N
80°W 75°W 77°30'W
•
••••••••••
•••••••
•
•
•
••• •••••• • ••• •
•• •
• •••••
•
•
•• ••
••
••••• ••••• ••••••
••
•
••
•
••• •••••
••
••••
••
•••••••
••
•
•
••
•••
•

PENNSYLVANIA

NEW YORK
OHIO

WEST VIRGINIA

MARYLAND

DELAWARE

VIRGINIA
Fig. 4. Seismicity of Pennsylvania and surrounding regions, 1970–2012. Shading indicates areas underlain by deposits of the Marcellus Shale. Blue dots, earthquakes before 2005; red dots, after 2005. Seismicity was determined by the Lamont Doherty Earth Ob- servatory (45).
12 JULY 2013 VOL 341 SCIENCE www.sciencemag.org
1225942-4
REVIEW
on August 7, 2013www.sciencemag.orgDownloaded from
below land surface. To date, more than 7 × 106 m3
of brine have been injected. One operational ob-
jective, based on both the RMA and Rangely
experiences, was the need to minimize the mag-
nitude of earthquakes induced by injection.

A local seismic network was established in
1985 to determine background levels of seis-
micity before the drilling of the well and initial
injection tests. Between 1985 and June 1996,
only three tectonic earthquakes were detected
within 15 km of the well and just 12 within 35 km
(33). However, hundreds of earthquakes were in-
duced during injection tests conducted between
1991 and 1995. Most of these earthquakes were
concentrated within 1 km of the injection point,
although a few were located 3 to 4 km from this
site. All events were belowM 3. The occurrence
of induced earthquakes is not notable here, as
injection required a bottom hole pressure in ex-
c e s so ft h eh y d r a u l i cf r a c t u r ep r e s s u r eo f7 0M P a .

High injection pressure was needed to keep
pace with the disposal requirements; consequent-
ly, induced earthquakes were expected when dis-
posal operations went into production in 1996.

Continuous monitoring of injection pressures and
volumes, along with seismicity, is being conducted
to insure the safe operation of the project. During
the first few years of operations, several of the in-
duced earthquakes exceeded M 3, necessitating
changes in injection procedures in an attempt to
limit the maximum magnitude. The dimension of
the activated zone also grew, with earthquakes as
far as 8 km from the injection point appearing
within a year and events to beyond 12 km several
years later (Fig. 5). Because seismicity rapidly
abated after each injection test, it was hypothe-
sized that occasional shutdowns of 20 days would
allow the fluid pressure to equilibrate, reducing the
potential for larger events ( 33). By itself, this
procedure proved inadequate, as a M 4.3 event
was induced in May 2000.

After this earthquake, a new procedure was
introduced in 2000 that involved periodic 20-day
shutdowns and a 33% reduction in the injec-
tion volume, which initially reduced the required
bottom hole pressure to 78 MPa. Over the fol-
lowing decade, the pressure required to inject that
volume steadily increased to more than 84 MPa
in 2012, drawing the revised strategy into ques-
tion, as a steadily increasing injection pressure is
not sustainable in the long term. On 24 January
108°45'W
109°W
109°W
108°45'W
38°15'N 38°15'N
06 3 KilometersN
Paradox
Mw 3.9
90 141
Injection well
Dolores Ri
ver
Paradox Valley
Fig. 5. Seismicity near Paradox Valley, Colorado.The U.S. Bureau of Reclamation extracts saline groundwater from shallow wells where the Dolores River crosses Paradox Valley to prevent its entry into the Colorado River system. Since 1996, the brine has been disposed of by injection into a 4.3-km-deep UIC class V well.

Injection has induced more than 1500 earthquakes withM ≥ 1, including theMw

3.9 earthquake on 25 January 2013, which was located 8 km northwest of the well. www.sciencemag.org SCIENCE VOL 341 12 JULY 2013 1225942-5 REVIEW
on August 7, 2013www.sciencemag.orgDownloaded from
2013, a Mw 3.9 earthquake occurred 8 km north-
west of the well in a previously active cluster,
causing strong shaking in the town of Paradox,
Colorado (Fig. 5). As a consequence, injection
was halted for 12 weeks before restarting at a
reduced rate. The Paradox V alley experience il-
lustrates how long-term, high-volume injection
can lead to the continued expansion of the seis-
mically activated region and the triggering of
large-magnitude events many kilometers from
the injection well more than 15 years after ob-
servation of the initial seismic response. This case
study also illustrates the challenges for manag-
ing the risk once seismicity has been induced.

Other Causes of Induced Earthquakes
According to the effective-stress model described
above, earthquakes can be induced by either re-
ducing the effective normal stress or raising the
shear stress (3–5). It has been known for decades
that large reservoirs can induce earthquakes either
from the effect of the elastic load of the reservoir
or by diffusion of elevated pore pressure ( 34).

Well-known examples include the deadly 1967
M 6.3 earthquake in Koyna, India ( 35). Yet,
establishing a causal connection can be difficult
when natural seismicity occurs nearby. For ex-
ample, the debate about the role of the Zipingpu
reservoir in triggering theM
w 7.9 2005 Wenchuan,
China, earthquake may never be resolved (36, 37).

What is clear, however, is that deep reservoirs
in tectonically active zones carry a real risk of
inducing damaging earthquakes.

Earthquakes throughout the world are also
recognized to be associated with mining, petro-
leum and gas production, and geothermal energy
extraction. Withdrawal of large volumes of fluid or
gas from a reservoir or creation of a void space in
a mine may modify the state of stress sufficiently
to induce earthquakes that relax the stress pertur-
bations (4). Production may also release tectonic
stress. The long-term pumping of groundwater may
have induced the deadly M
w 5.1 earthquake in
Lorca, Spain, on 11 May 2011 (38). Pore-pressure
changes alone can also induce seismicity, such as
by waterflooding for secondary recovery of oil or
to maintain the fluid level in a geothermal reser-
voir, or when a mine is abandoned and allowed to
flood (3, 4). The physical connection between op-
erational parameters such as injected volume and
the seismic response can be complex. In the Salton
Sea Geothermal Field, for example, the seismicity
rate positively correlates with the net volume of
produced fluid (extraction minus injection) rather
than net injection, as would be expected if seis-
micity rate simply tracked pore pressure (39). This
underscores the importance of geomechanical mod-
eling for transferring understandings developed
in one setting to others.

Hazard and Risk of Induced Earthquakes
The hazard from earthquakes depends on proximity
to potential earthquake sources, their magnitudes,
and rates of occurrence and is usually expressed
in probabilistic terms (1, 40). The U.S. National
Seismic Hazard Map, for example, gives the ex-
ceedance probabilities for a variety of ground-
motion measures from which the seismic design
provisions in the building codes are derived (Fig. 1)
(1). Our understanding of the hazard will evolve
as new information becomes available about the
underlying earthquake sources, which are ideally
derived from a combination of fault-based infor-
mation and historical seismicity. Accounting for the
hazard of induced earthquakes, however, presents
some formidable challenges.

In the current U.S. map (Fig. 1), for example,
the estimated hazard in most parts of the central
and eastern regions of the country derives exclu-
sively from historical seismicity. How should in-
creases in the earthquake rate since 2009 (Fig. 2)
be incorporated in the model? Should identified
or suspected induced earthquakes be treated the
same as or differently than natural events? In
particular, do induced earthquakes follow the
same magnitude-frequency distribution models
as natural earthquakes? This issue has particular
importance, as the high end of the magnitude dis-
tribution, where events are infrequent, contributes
disproportionately to both the hazard and risk.

Although injection-induced earthquakes have done
only minor damage in the United States to date
(5), the 2011 central Oklahoma earthquake was
the same magnitude as the 1986 San Salvador,
El Salvador, tectonic earthquake that killed more
than 1500 people, injured more than 10,000, and
left 100,000 homeless (41) .L o s s e so nt h i ss c a l e are unlikely in North America and northern Europe,
where a catastrophic building collapse in aM
w 5.7
earthquake is unlikely, but the same cannot be said
for large portions of the world where nonductile
concrete frame or unreinforced masonry buildings
are prevalent. The earthquake that killed nine and
caused serious damaged Lorca, Spain, was even
smaller at M
w 5.1 (40). The heavy losses in this
possibly induced earthquake resulted from the ex-
posure of many fragile buildings to strong shaking
from this very shallow-focus earthquake (42). This
event should serve as a reminder that risk is the
product of the hazard, exposure, and vulnerability.

Unknown Knowns
Ignorance of the things that we understand we
should know but do not leaves us vulnerable
to unintended consequences of our actions. The
effective-stress model provides straightforward guid-
ance for avoiding induced earthquakes but re-
quires knowledge that we rarely possess of the
stress state and pore pressure acting on the fault.

Quantitative predictions from the model depend
on knowing initial stress and pore-pressure con-
ditions and how perturbations to those conditions
due to injection will affect the surroundings. For
example, pore-pressure changes in a fault kilome-
ters from the injection point depend on the hy-
drologic characteristics of connecting pathways
that will, in all likelihood, be poorly known. The
seismic response might not take place immediately,
and decades may elapse before a damaging event
occurs, as illustrated by the recent Paradox V alley
earthquake and possibly the central Oklahoma
earthquake as well. Simply injecting water by grav-
ity feed (pouring it down the well with no surface
pressure) sounds safe enough. But if the deep aquifer
system was originally underpressured and the faults
were in frictional equilibrium with the stress (2),
this apparently benign type of injection can bring
faults to failure by raising the water table and, hence, the pore pressure acting on the faults.

The fact that the great majority of UIC class II
injection wells in the United States appear to be
aseismic, at least for earthquakesM
w > 3, suggests
that ambient conditions in geologic formations
commonly approved for disposal are far enough
removed from failure that injection can be done
with low risk, provided that the pressure perturba-
tion remains confined within the intended forma-
tion. The largest injection-induced events have all
involved faulting that is considerably deeper than
the injection interval (13, 16, 30, 43), suggesting
that transmission of increased pressure into the
basement elevates the potential for inducing earth-
quakes. Consequently, detection of seismicity in
the vicinity of the well or changes in seismicity in
the neighborhood should prompt reevaluation
of the hazard.

License and operational requirements for UIC
class II wells in the United States are regulated
under the Safe Drinking Water Act, by the U.S.

Environmental Protection Agency or by dele-
gation of authority to state agencies. The law’ s
provisions are primarily directed toward protec-
tion of potable aquifers by requiring injection into
formations deep below and geologically isolated
from drinking water sources. As such, the law
focuses on well integrity , protection of imperme-
able barriers above the injection zone, and setting
operational injection pressure limits to avoid hy-
draulically fracturing the well. Diffusion of pore
pressure into basement faults or injection pres-
sure that would raise critically stressed faults to
failure is not considered in U.S. federal regula-
tions. From a scientific standpoint, measuring the
initial stress state and pore pressure, tracking of
injection history, and careful seismic monitoring
would be of great value. At present, little more is
r e q u i r e db yr e g u l a t i o nt h a na ne s t i m a t eo ft h e fracture pressure (not to be exceeded) and monthly
reporting of total injection volume and average
injection pressure. In most cases, this information
is not sufficient to apply the effective-stress mod-
el or gain an understanding of the hazard posed
by injection activity.

Reducing the Risk of
Injection-Induced Earthquakes
How can the risk of inducing damaging earth-
quakes through human activity be minimized
in an information-poor environment? Long-term
and high-volume injection in deep wells clearly
carries some risk (18), even though most wells
are apparently aseismic ( 5). In contrast, earth-
quakes induced during hydraulic fracturing have
lower risk because of their much smaller magni-
tudes. The largest fracking-induced earthquakes
12 JULY 2013 VOL 341 SCIENCE www.sciencemag.org
1225942-6
REVIEW
on August 7, 2013www.sciencemag.orgDownloaded from
(24, 26) have all been below the damage thresh-
old for modern building codes.

One approach for managing the risk of
injection-induced earthquakes involves setting
seismic activity thresholds that prompt a reduc-
tion in injection rate or pressure or, if seismic
activity increases, further suspension of injec-
tion ( 44). Such “traffic-light” systems have been
used selectively, going back to at least the RMA
well pump tests in 1966 –1967. The traffic-light
system used in in Basel, Switzerland (7), did not
stop the four M
w 3 earthquakes from happening
but might have prevented larger events. The de-
cision to stop injection in the Youngstown, Ohio,
well, based on the seismicity (12)a n dm a d et h e
day before theM
w 4.0 event, resulted in seismicity
near the well declining within a month. All of
these examples feature better seismic monitoring
capabilities than currently exist in much of the
United States or most of the rest of the world.

Lowering the magnitude-detection threshold in
regions where injection wells are concentrated to
belowM
w 2 would certainly help, as a traffic-light
system using the current U.S. detection threshold
of Mw 3 in many of these areas would have limited
value. Improvements in the collection and time-
liness of reporting of injection data to regulatory
agencies would provide much-needed information
on hydrologic conditions potentially associated with
induced seismicity. In particular, daily reporting of
volumes, peak, and mean injection pressures would
be a step in the right direction, as would measure-
ment of the pre-injection formation pressure.

Ultimately, better knowledge of the stress and
pressure conditions at depth; the hydrogeolgic
framework, including the presence and geometry of
faults; and the location and mechanisms of natural
seismicity at a few sites will be needed to develop
a predictive understanding of the h azard posed
by induced earthquakes. Industry, regulatory agen-
cies, and the public are all aware that earthquakes
can be induced by fluid injection. Industry needs
clear requirements under which to operate, regu-
lators must have a firm scientific foundation for
those requirements, and the public needs as-
surance that the regulations are adequate and are
being observed.

References and Notes

1. M. D. Petersen, A. D. Frankel, S. C. Harmsen,
C. S. Mueller, K. M. Haller, R. L. Wheeler, R. L. Wesson, Y. Zeng, O. S. Boyd, D. M. Perkins, N. Luco, E. H. Field, C. J. Wills, K. S. Rukstales, “Documentation for the 2008 update of the United States National Seismic Hazard Map,” U.S. Geol. Surv. Open-File Rep. 2008–1128 (2008).

2. J. Townend, M. D. Zoback, How faulting keeps the crust strong. Geology 28, 399– 402 (2000). doi: 10.1130/0091- 7613(2000)28<399:HFKTCS>2.0.CO;2

3. C. Nicholson, R. L. Wesson, “Earthquake hazard associated with deep well injection: A report to the U.S. Environmental Protection Agency, ” U.S. Geol. Surv. Bull. 1951 (1990); http://pubs.usgs.gov/bul/1951/report.pdf.

4. A. McGarr, D. Simpson, L. Seeber, “Case histories of induced and triggered seismicity, ” International
Handbook of Earthquake and Engineering Seismology
(Academic Press, Waltham, MA, 2002), vol. 8, chap. 40.

5. Committee on Induced Seismicity Potential in Energy
Technologies, Induced Seismicity Potential in Energy
Technologies (National Research Council, Washington,
DC, 2012); http://dels.nas.edu/Report/Induced-Seismicity- Potential-Energy-Technologies/13355.

6. K. F. Evans, A. Zappone, T. Kraft, N. Deichmann, F. Moia, A survey of the induced seismic responses to fluid
injection in geothermal and CO
2 reservoirs in Europe.

Geothermics 41,3 0 – 54 (2012). doi: 10.1016/
j.geothermics.2011.08.002

7. N. Deichmann, D. Giardini, Earthquakes induced by the stimulation of an enhanced geothermal system below
Basel (Switzerland). Seismol. Res. Lett. 80,
784– 798 (2009). doi: 10.1785/gssrl.80.5.784

8. T. van Eck, F. Goutbeek, H. Haak, B. Dost, Seismic hazard due to small-magnitude, shallow-source induced
earthquakes in The Netherlands. Eng. Geol. 87, 105– 121 (2006). doi: 10.1016/j.enggeo.2006.06.005

9. J. Tagliabue, “Parts of low country are now quake
country,” New York Times , 26 March 2013, p. A6.

10. F. L. Vernon, L. Astiz, Seismicity in the mid-continental U.S. as recorded by the Earthscope USArray Transportable Array. Geol. Soc. Am. Abstr. Programs 44, 511 (2012).

11. “Technical report: Central and eastern United States seismic source characterization for nuclear facilities, ” Appendix B (Electric Power Research Institute, Palo Alto, CA; U.S. Department of Energy and U.S. Nuclear
Regulatory Commission, Washington, DC; 2012).

12. W.-Y. Kim, Induced seismicity associated with fluid injection into a deep well in Youngstown, Ohio.

J. Geophys. Res. 10.1002/jgrb.50247 (2013).

13. S. Horton, Disposal of hydrofracking waste fluid by injection into subsurface aquifers triggers earthquake
swarm in central Arkansas with potential for damaging
earthquake. Seismol. Res. Lett. 83, 250 – 260 (2012).
doi: 10.1785/gssrl.83.2.250

14. S. D. Davis, W. D. Pennington, Induced seismic
deformation in the Cogdell oil field of west Texas.

Bull. Seismol. Soc. Am. 79, 1477– 1495 (1989).

15. W. D. Pennington, S. D. Davis, The evolution of seismic barriers and asperities caused by the depressuring of
fault planes in oil and gas fields of south Texas.

Bull. Seismol. Soc. Am. 76, 939 – 948 (1986).

16. K. M. Kerenan, H. M. Savage, G. A. Abers, E. S. Cochran, Potentially induced earthquakes in Oklahoma, USA: Links between wastewater injection and the 2011 M
w 5.7
earthquake sequence. Geology 41, 699 – 702 (2013).
doi: 10.1130/G34045.1

17. W. A. Brown, C. Frohlich, Investigating the cause of the 17 May 2012 M 4.8 earthquake near Timpson, east Texas
(abstr.). Seismol. Res. Lett. 84, 374 (2013).

18. C. Frohlich, Two-year survey comparing earthquake
activity and injection-well locations in the Barnett
Shale, Texas. Proc. Natl. Acad. Sci. U.S.A. 109,
13934– 13938 (2012). doi: 10.1073/pnas.1207728109;
pmid: 22869701

19. M. K. Hubbert, W. W. Rubey, Role of fluid pressure
in mechanics of overthrust faulting. Geol. Soc.

Am. Bull. 70, 115 – 206 (1959). doi: 10.1130/0016-
7606(1959)70[115:ROFPIM]2.0.CO;2

20. C. B. Raleigh, J. H. Healy, J. D. Bredehoeft,
An experiment in earthquake control at Rangely,
Colorado. Science 191, 1230– 1237 (1976).
doi: 10.1126/science.191.4233.1230; pmid: 17737698

21. C. Barton, D. Moos, K. Tezuka, Geomechanical
wellbore imaging: Implications for reservoir fracture
permeability. AAPG Bull. 93, 1551– 1569 (2009).
doi: 10.1306/06180909030

22. W. H. Bakun et al. , Implications for prediction and hazard assessment from the 2004 Parkfield earthquake.

Nature 437, 969 – 974 (2005). doi: 10.1038/
nature04067; pmid: 16222291

23. N. J. van der Elst, H. M. Savage, K. M. Keranen,
G. A. Abers, Enhanced remote earthquake triggering at
fluid-injection sites in the midwestern United States.

Science 341, 164 – 167 (2013).

24. A. Holland, Earthquakes triggered by hydraulic fracturing in south-central Oklahoma. Bull. Seismol. Soc. Am. 103, 1784– 1792 (2013).

25. C. A. Green, P. Styles, “Preese Hall shale gas fracturing:

Review and recommendations for induced seismicity
mitigation” (2012); www.gov.uk/government/uploads/
system/uploads/attachment_data/file/15745/5075-
preese-hall-shale-gas-fracturing-review.pdf.

26. “Investigation of observed seismicity in the Horn River Basin” (BC Oil and Gas Commission, Victoria, British
Columbia, Canada, 2012); www.bcogc.ca/node/8046/
download?documentID=1270.

27. G. R. Keller, A. Holland, “Oklahoma Geological
Survey evaluation of the Prague earthquake sequence
of 2011” (Oklahoma Geological Survey, Norman, OK,
2013); www.ogs.ou.edu/earthquakes/OGS_
PragueStatement201303.pdf.

28. C. Frohlich, C. Hayward, B. Stump, E. Potter,
The Dallas – Fort Worth earthquake sequence:

October 2008 through May 2009. Bull. Seismol. Soc. Am.
101, 327 – 340 (2011). doi: 10.1785/0120100131

29. E. Janská , L. Eisner, Ongoing seismicity in the Dallas-Fort Worth area. Leading Edge 31, 1462 – 1468 (2012).
doi: 10.1190/tle31121462.1

30. J. H. Healy, W. W. Rubey, D. T. Griggs, C. B. Raleigh, The Denver earthquakes. Science 161, 1301 – 1310
(1968). doi: 10.1126/science.161.3848.1301;
pmid: 17831340

31. R. B. Herrmann, S.-K. Park, The Denver earthquakes of 1967-1968. Bull. Seismol. Soc. Am. 71, 731 – 745
(1981).

32. P. A. Hsieh, J. S. Bredehoeft, A reservoir analysis of the Denver earthquakes: A case of induced seismicity.

J. Geophys. Res. 86, 903 – 920 (1981). doi: 10.1029/
JB086iB02p00903

33. J. Ake, K. Mahrer, Deep-injection and closely monitored induced seismicity at Paradox Valley, Colorado.

Bull. Seismol. Soc. Am. 95, 664 – 683 (2005).
doi: 10.1785/0120040072

34. D. W. Simpson, W. S. Leith, Two types of reservoir-induced seismicity. Bull. Seismol. Soc. Am. 78,2 0 2 5– 2040 (1988).

35. H. Gupta, A review of recent studies of triggered
earthquakes by artificial water reservoirs with special emphasis on earthquakes in Koyna, India. Earth Sci. Rev. 58, 279 – 310 (2002). doi: 10.1016/S0012-
8252(02)00063-6

36. S. Ge, M. Liu, N. Lu, J. W. Godt, N. Luo, Did the
Zipingpu Reservoir trigger the 2008 Wenchuan
earthquake? Geophys. Res. Lett. 36, L20315 (2009).
doi: 10.1029/2009GL040349

37. K. Deng et al., Evidence that the 2008 Mw 7.9 Wenchuan earthquake could not have been induced by the Zipingpu
Reservoir. Bull. Seismol. Soc. Am. 100, 2805– 2814
(2010). doi: 10.1785/0120090222

38. P. J. Gonzá lez, K. F. Tiampo, M. Palano, F. Cannavó , J. Ferná ndez, The 2011 Lorca earthquake slip distribution controlled by groundwater crustal unloading. Nat. Geosci. 5, 821 – 825 (2012). doi: 10.1038/ngeo1610

39. E. E. Brodsky, L. J. Lajoie, Anthropogenic seismicity rates and operational parameters at the Salton Sea Geothermal Field. Science 10.1126/science.1239213 (2013).
doi: 10.1126/science.1239213

40. R. K. McGuire, “Seismic hazard and risk analysis, ” Earthquake Engineering Research Institute Monograph
MNO-10 (2004).

41. D. H. Harlow, R. A. White, The San Salvador earthquake of 10 October 1986 and its historical context. Bull.

Seismol. Soc. Am. 83, 1143– 1154 (1993).

42. J.-P. Avouac, Earthquakes: Human-induced shaking.

Nat. Geosci. 5, 763– 764 (2012). doi: 10.1038/ngeo1609

43. J. L. Rubinstein, W. L. Ellsworth, The 2001 -
present triggered seismicity sequence in the Raton
basin of southern Colorado/Northern New Mexico.

Seismol. Res. Lett. 84, 374 (2013).

44. M. D. Zoback, Managing the seismic risk posed by
wastewater disposal. Earth Magazine 57,3 8 – 43 (2012).

45. www.ldeo.columbia.edu/LCSN/index.php.

Acknowledgments: This paper is a contribution of the
USGS’s John Wesley Powell Center Working Group on
Understanding Fluid Injection Induced Seismicity. I thank L. Block, C. Frohlich, S. Hickman, W. Leith, A. McGarr, J. Rubinstein, and an anonymous reviewer for insightful comments during the development of this paper.

10.1126/science.1225942
www.sciencemag.org SCIENCE VOL 341 12 JULY 2013 1225942-7 REVIEW
on August 7, 2013www.sciencemag.orgDownloaded from
3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 1/8 8,300,000Metric Tons of Carbon Dioxide (CO ) equivalent This is equivalent to greenhouse gas emissions from:

This is equivalent to CO emissions from:
2 1,788,395 gasoline-powered passenger
vehicles driven for one year
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#vehicles>
20,602,306,153 miles driven by an average
gasoline-powered passenger vehicle
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#miles>
2 933,948,464 gallons of gasoline consumed
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#gasoline>
815,324,165 gallons of diesel consumed
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#diesel>
9,183,196,553 pounds of coal burned
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator-

3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 2/8 calculations-and-references#lbscoal>
109,876 tanker trucks' worth of gasoline
<https://epa.gov/energy/greenhouse-gases-equivalencies- calculator-calculations-and-references#tankers>
1,045,493 homes' energy use for one year
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#houseenergy>
1,614,969 homes' electricity use for one year
<https://epa.gov/energy/greenhouse-gases-equivalencies- calculator-calculations-and-references#houseelec>
45,830 railcars' worth of coal burned
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#railcars>
19,216,255 barrels of oil consumed
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#oil>

3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 3/8 This is equivalent to greenhouse gas emissions avoided by:
338,928,280 propane cylinders used for home
barbeques <https://epa.gov/energy/greenhouse-gases-
equivalencies-calculator-calculations-and-references#propane>

2.2 coal-fired power plants in one year
<https://epa.gov/energy/greenhouse-gases-equivalencies- calculator-calculations-and-references#coalplant>

20.9 natural gas-fired power plants in
one year <https://epa.gov/energy/greenhouse-gases-
equivalencies-calculator-calculations-and-references#gasplant> 1,009,633,964,2 number of smartphones charged
<https://epa.gov/energy/greenhouse-gases-equivalencies- calculator-calculations-and-references#smartphones>
2,871,972 tons of waste recycled instead of
landfilled <https://epa.gov/energy/greenhouse-gases-
equivalencies-calculator-calculations-and-references#recycle>

3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 4/8 This is equivalent to carbon sequestered by:
410,282 garbage trucks of waste recycled
instead of landfilled <https://epa.gov/energy/greenhouse- gases-equivalencies-calculator-calculations-and-references#gtrucks> 359,270,800 trash bags of waste recycled
instead of landfilled <https://epa.gov/energy/greenhouse- gases-equivalencies-calculator-calculations-and-references#trash> 2,256 wind turbines running for a year
<https://epa.gov/energy/greenhouse-gases-equivalencies- calculator-calculations-and-references#wind>
314,578,404 incandescent lamps switched to
LEDs <https://epa.gov/energy/greenhouse-gases-equivalencies- calculator-calculations-and-references#lights>
137,241,214 tree seedlings grown for 10 years
<https://epa.gov/energy/greenhouse-gases-equivalencies- calculator-calculations-and-references#seedlings>

3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 5/8

9,822,514 acres of U.S. forests in one year
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#pineforests>
55,984 acres of U.S. forests preserved
from conversion to cropland in one year
<https://epa.gov/energy/greenhouse-gases-equivalencies-calculator- calculations-and-references#deforestation>

3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 6/8 3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 7/8 3/16/23, 11:42 AM Greenhouse Gas Equivalencies Calculator | US EPA https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator#results 8/8 label // // //
3/16/23, 11:40 AM Basic Information about Oil and Natural Gas Air Pollution Standards | US EPA https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/basic-information-about-oil-and-natural-gas#:~:text=In addition to helping form,and other … 1/5 Controlling Air Pollution from the Oil and Natural Gas
Industry
CONTACT US <https://epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/forms/contact-us-about-controlling-air> Basic Information about Oil and
Natural Gas Air Pollution
Standards
The oil and natural gas industry includes a wide range of operations and equipment, from wells to natural gas gathering lines and processing facilities, to storage tanks, and transmission and distribution pipelines.

The industry is a significant source of emissions of methane <https://epa.gov/ghgemissions/overview- greenhouse-gases#methane>, a potent greenhouse gas with a global warming potential more than 25 times that of carbon dioxide.

It also is the largest industrial source of emissions of volatile organic compounds (VOCs), a group of chemicals that contribute to the formation of ground-level ozone (smog) <https://epa.gov/ozone- pollution/health-eects-ozone-pollution>. Exposure to ozone is linked to a wide range of health eects, including aggravated asthma, increased emergency room visits and hospital admissions, and premature death.

In addition to helping form ozone, VOC emissions from the oil and gas industry include air toxics <https://epa.gov/haps> such as benzene, ethylbenzene, and n-hexane, also come from this industry. .Air toxics are pollutants known, or suspected of causing cancer and other serious health eects Oil and Natural Gas Air Standards Home <https://epa.gov/controlling-air-pollution-oil-and-natural-gas- industry>
An oicial website of the United States government
Here’s how you know
MENU
Search EPA.gov
3/16/23, 11:40 AM Basic Information about Oil and Natural Gas Air Pollution Standards | US EPA https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/basic-information-about-oil-and-natural-gas#:~:text=In addition to helping form,and other … 2/5 Actions and Notices <https://epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/actions-and-notices- about-oil-and-natural>
Implementation <https://epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/implementation-oil-and- natural-gas-air>
Contact Us <https://epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/forms/contact-us-about-controlling- air> to ask a question, provide feedback, or report a problem.

LAST UPDATED ON SEPTEMBER 29, 2022
Basic Information
3/16/23, 11:40 AM Basic Information about Oil and Natural Gas Air Pollution Standards | US EPA https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/basic-information-about-oil-and-natural-gas#:~:text=In addition to helping form,and other … 3/5 3/16/23, 11:40 AM Basic Information about Oil and Natural Gas Air Pollution Standards | US EPA https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/basic-information-about-oil-and-natural-gas#:~:text=In addition to helping form,and other … 4/5 Discover.

Accessibility Statement <https://epa.gov/accessibility/epa-accessibility-statement> Budget & Performance <https://epa.gov/planandbudget>
Contracting <https://epa.gov/contracts>
EPA www Web Snapshot <https://epa.gov/utilities/wwwepagov-snapshots> Grants <https://epa.gov/grants>
No FEAR Act Data <https://epa.gov/ocr/whistleblower-protections-epa-and-how-they-relate-non-disclosure- agreements-signed-epa>
Plain Writing <https://epa.gov/web-policies-and-procedures/plain-writing> Privacy <https://epa.gov/privacy>
Privacy and Security Notice <https://epa.gov/privacy/privacy-and-security-notice> Connect.

Data.gov <https://www.data.gov/>
Inspector General <https://epa.gov/oice-inspector-general/about-epas-oice-inspector-general> Jobs <https://epa.gov/careers>
Newsroom <https://epa.gov/newsroom>
Open Government <https://epa.gov/data>
Regulations.gov <https://www.regulations.gov/>
Subscribe <https://epa.gov/newsroom/email-subscriptions-epa-news-releases> USA.gov <https://www.usa.gov/>
White House <https://www.whitehouse.gov/>
Ask.

Contact EPA <https://epa.gov/home/forms/contact-epa>
EPA Disclaimers <https://epa.gov/web-policies-and-procedures/epa-disclaimers> Hotlines <https://epagov/aboutepa/epa-hotlines>
3/16/23, 11:40 AM Basic Information about Oil and Natural Gas Air Pollution Standards | US EPA https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry/basic-information-about-oil-and-natural-gas#:~:text=In addition to helping form,and other … 5/5 Hotlines <https://epa.gov/aboutepa/epahotlines>
FOIA Requests <https://epa.gov/foia>
Frequent Questions <https://epa.gov/home/frequent-questions-specific-epa-programstopics> Follow.

Ecotoxicology (2020) 29:1399 –1408
https://doi.org/10.1007/s10646-020-02255-8
Ultraviolet-assisted oiling assessment improves detection of oiled birds experiencing clinical signs of hemolytic anemia after exposure to the Deepwater Horizon oil spill
Jesse A. Fallon 1 ●
Eric P. Smith 2 ●
Nina Schoch 3 ●
James D. Paruk 4 ●
Evan M. Adams 5 ●
David C. Evers 5 ●
Patrick G. R. Jodice 6 ●
Marie Perkins 7 ●
Dustin E. Meattey 5 ●
William A. Hopkins 1
Accepted: 11 July 2020 / Published online: 12 August 2020 © Springer Science +Business Media, LLC, part of Springer Nature 2020 Abstract
While large-scale oil spills can cause acute mortality events in birds, there is increasing evidence that sublethal oil exposure can trigger physiological changes that have implications for individual performance and survival. Therefore, improved methods for identifying small amounts of oil on birds are needed. Because ultraviolet (UV) light can be used to identify thin crude oil ﬁlms in water and on substrate that are not visually apparent under normal lighting conditions, we hypothesized that UV light could be useful for detecting small amounts of oil present on the plumage of birds. We evaluated black skimmers ( Rynchops niger ), brown pelicans ( Pelecanus occidentalis ), clapper rails ( Rallus crepitans ), great egrets ( Ardea alba), and seaside sparrows ( Ammodramus maritimus ) exposed to areas affected by the Deepwater Horizon oil spill in the Gulf of Mexico as well as from reference areas from 20 June, 2010 to 23 February, 2011. When visually assessed without UV light, 19.6% of birds evaluated from areas affected by the spill were determined to be oiled (previously published data), whereas when examined under UV light, 56.3% of the same birds were determined to have oil exposure. Of 705 individuals examined in areas potentially impacted by the spill, we found that ﬂuorescence under UV light assessment identi ﬁed 259 oiled birds that appeared to be oil-free on visual exam, supporting its utility as a simple tool for improving detection of modestly oiled birds in the ﬁeld. Further, UV assessment revealed an increase in qualitative severity of oiling (approximate % of body surface oiled) in 40% of birds compared to what was determined on visual exam. Additionally, black skimmers, brown pelicans, and great egrets exposed to oil as determined using UV light experienced oxidative injury to erythrocytes, had decreased numbers of circulating erythrocytes, and showed evidence of a regenerative hematological response in the form of increased reticulocytes. This evidence of adverse effects was similar to changes identi ﬁed in birds with oil exposure as determined by visual examination without UV light, and is consistent with hemolytic anemia likely caused by oil exposure. Thus, UV assessment proved useful for enhancing detection of birds exposed to oil, but did not increase detection of birds experiencing clinical signs of anemia compared to standard visual oiling assessment. We conclude that UV light evaluation can help identify oil exposure in many birds that would otherwise be identi ﬁed visually as unexposed during oil spill events.

Keywords Deepwater horizon
●
Oil spill
●
Heinz bodies
●
Ultraviolet ﬂuorescence
●
Hemolytic anemia
* Jesse A. Fallon
[email protected]
1 Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, USA
2 Department of Statistics, Virginia Tech, Blacksburg, VA, USA 3 Adirondack Center for Loon Conservation, Ray Brook, NY, USA 4 Saint Joseph ’s College of Maine, Portland, ME, USA
5 Biodiversity Research Institute, Portland, ME, USA
6 U.S. Geological Survey South Carolina Cooperative Fish and Wildlife Research Unit, Clemson University, Clemson, SC, USA 7 John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
Supplementary information The online version of this article ( https:// doi.org/10.1007/s10646-020-02255-8) contains supplementary material, which is available to authorized users.
1234567890();,:
1234567890();,:

Introduction
Acute avian mortality associated with large-scale oil spills is well documented, with seabirds, waterfowl, and colonial waterbirds at particular risk (e.g., Piatt et al. 1990; Iverson and Esler 2010; Munilla et al. 2011; USFWS 2011).

However, there is increasing evidence that sublethal expo- sure (modest external oiling that does not result in rapid mortality) can have important impacts upon individual
health and may affect population dynamics, which could
inﬂuence damage assessments and subsequent restoration
and mitigation efforts (Seiser et al. 2000; Trust et al. 2000; Golet et al. 2002; Alonso-Alvarez et al. 2007; Harr et al. 2017; Fallon et al. 2018). Consequently, it is important not only to identify birds that have died from oil exposure, but also to identify birds with sublethal exposure to better estimate the number of birds at risk following both small- and large-scale oil spill events. However, identifying small amounts of oil on feathers can be dif ﬁcult, especially in birds with dark plumage, under natural lighting conditions.

Failure to detect modest oiling may result in inaccurate estimates of the number of birds exposed during oil spills events. Therefore, there is a need for simple, reliable tech- niques to identify small amounts of oil on birds.

Crude oil ﬂuoresces under ultraviolet (UV) light (Bur-
lamacchi et al. 1983; Colligan and LaManna 1993; Fingas and Brown 2014). This attribute has led to its use to
improve detection of oil in several abiotic matrices. For example, UV light can be used to enhance detection of oil on or below the surface of a body of water as well as on snow and ice (Fingas and Brown 2000; Fingas and Brown
2013). Remote UV sensors are commonly used to monitor
oil ﬁlms associated with spills in very thin layers down to

0.1 µm (Fingas and Brown 1997; Brekke and Solberg 2005; Jha et al. 2008). Thus, we hypothesized that UV light may also be useful to detect small amounts of oil on the feathers of captured birds that might not be apparent under normal light conditions.

Birds experiencing modest exposure to crude oil can
experience myriad physiological effects, including in ﬂam- mation, immunosuppression, and oxidative damage to cells (Fry et al. 1986; Leighton 1986; Leighton 1995; Briggs
et al. 1996; Golet et al. 2002). These sublethal effects can negatively impact growth, alter organ function, reduce
reproductive success, and likely increase risk of disease (Briggs et al. 1996; Esler et al. 2000; Giese et al. 2000; Eppley and Rubega 1990; Alonso-Alvarez et al. 2007
). Of
the sublethal, physiological impacts resulting from avian exposure to oil spills, oxidative damage to erythrocytes and subsequent anemia are of particular interest during oil spill investigations, as such injury can be evaluated in blood samples taken from live birds. Hemolytic anemia has been demonstrated in several species of birds exposed to crude oil under both experimental (e.g., Leighton et al.
1983, 1985; Fry and Lowenstine 1985; Harr et al. 2017) and natural conditions (Yamato et al. 1996; Troisi et al. 2007; Fallon et al. 2018). Although most work has focused on
severe oiling, recent evidence indicates that small amounts of visible oiling correlate with oxidative injury to ery- throcytes in several species of birds (Fallon et al. 2018).

In this investigation, we evaluated the utility of UV
ﬂuorescence as a tool to identify birds with small amounts of oil on their plumage that might otherwise be missed by traditional visual oiling assessment during and in the
immediate aftermath of the 2010 Deepwater Horizon oil
spill in the Gulf of Mexico, USA. To achieve this objective, we determined the presence and severity of oiling (% of body surface oiled) by visual inspection under natural light (visual oiling assessment) and then again under UV light (UV oiling assessment) in black skimmers ( Rynchops niger, BLSK), brown pelicans ( Pelecanus occidentalis , BRPE), great egrets ( Ardea alba, GREG ), clapper rails ( Rallus crepitans, CLRA), and seaside sparrows ( Ammodramus
maritimus, SESP). Second, we evaluated relationships
between severity of visible oiling, UV oiling, and a suite of hematologic parameters characteristic of adverse effects from oil exposure in BLSK, BRPE, and GREG. We eval-
uated these relationships to determine whether UV oiling assessment improved detection of the number of birds
experiencing adverse clinical signs compared to those
detected through visual assessment alone.

Methods
Study area and focal species
Our ﬁve focal species represent a diversity of ecological niches, which could in ﬂuence their relative susceptibility to oil exposure. Clapper rails and SESP are year-round resi- dents along the Gulf Coast, inhabit salt marshes surrounded by open water, and are omnivorous, eating seeds and marine invertebrates (Post and Greenlaw 2020; Rush et al. 2020).

Black skimmers, recognized as a species with declining
populations (Vieira et al. 2018), were selected because of their unique surface water foraging strategy and because their nesting habits (sand and shell beaches and islands) put them at high risk for exposure to oil (Gochfeld et al. 2020).

Brown pelicans eat mostly ﬁsh and are at high risk of
dermal exposure to oil because they capture their food most often by diving after prey (Shields 2020). Great egrets forage for food in a wide range of habitats and are unique among the other species evaluated in this study because they are a wading bird that has diverse prey items, including ﬁshes, insects, marine invertebrates, small mammals, rep- tiles, and amphibians (McCrimmon et al. 2020).
1400 J. A. Fallon et al.

The procedures involving animals were conducted by
Biodiversity Research Institute with approval from the US Fish and Wildlife Service. We captured BLSK ( n = 120), BRPE ( n = 66), CLRA ( n = 100), GREG ( n = 54), and
SESP (n = 365) from reference areas and areas impacted by the Deepwater Horizon spill from 20 June, 2010 until 23 February, 2011. We captured BLSK with noose mats, box
traps, and cannon-nets, BRPE with noose traps, padded leg- hold traps, and net guns, CLRA by hand with night lighting from airboats as well as with drift fences leading to box traps, GREG with net guns, and SESP with targeted mist
netting (Mills and Ryder 1979; Crozier and Gawlik 2003; Herring et al. 2008; Perkins et al. 2010).

Sites affected by the Deepwater Horizon spill included
locations along coastal Louisiana, with ﬁve BRPE collected from coastal Mississippi, where exposure to oil from the Deepwater Horizon spill was likely (Fig. 1). Reference sites for BLSK, BRPE, and GREG included various locations
along coastal South Carolina and Georgia, USA where no
recent oiling events had been recorded (Fig. 2). Because CLRA and SESP maintain small home ranges, reference
sites for these two species included saline Juncus marshes, saline Spartina marshes, and brackish Phragmites marshes with no visible oil along coastal Louisiana, Mississippi, and Alabama (Fig. 1). We banded all birds with leg bands
appropriate for each species and released them at the cap- ture location after we completed oiling assessments and sample collection.

Visible and UV oiling assessment
We evaluated the majority of birds captured in both oiled and reference sites for evidence of visible oiling under natural lighting conditions, and assigned a visible oiling score of none (0% of plumage affected with visible oil), trace (<5% plumage affected), light (6 –20% plumage
affected) moderate (21 –40% plumage affected) or heavy
(>40% plumage affected; see Supplementary Figs. 1, 2). We competed this examination under physical restraint appro- priate for each species with wings in both extension and normal standing posture. We then placed each bird under an opaque canvas cover to block out natural light and exposed the plumage to UV light (Labino compact PH135 UV
spotlight, Labino AB Solna, Sweden, 365 nm peak UV-A).

We assigned a separate UV oiling score using the same ﬁve oil score categories. Thus, the same birds were categorized using two independent techniques (visible and UV oiling) to determine whether the use of a UV light source improved Fig. 1 Area of potential impact capture locations in Louisiana, Mis- sissippi and Alabama for American oystercatcher, black skimmer, brown pelican, and great egret. Also shown are reference capture locations and area of potential impact capture locations for clapper rail and seaside sparrow. Because these two species maintain small home ranges, we classi ﬁed Juncus marshes, saline Spartina marshes, and brackish Phragmites marshes with no known direct connectivity to the oil spill area as reference sites
Ultraviolet-assisted oiling assessment improves detection of oiled birds experiencing clinical signs of. . . 1401 detection and severity of oiling (see example in Supple- mentary Fig. 3).

Blood collection and sample handling
We collected blood in a subset of individual BLSK, BRPE, and GREG from the medial metatarsal vein or super ﬁcial ulnar vein using a 21G or 23G butter ﬂy catheter and lithium heparin and ethylenediaminetetraacetic acid (EDTA) vacu- tainers. These three species were selected for hematological analyses due to ease of blood collection and their relatively large body size. Immediately following collection, we ﬁlled two heparinized hematocrit tubes for packed cell volume (PCV) analysis. At this time, we also prepared new
methylene blue-stained blood smears to quantify Heinz
bodies and reticulocytes as described below. We placed
remaining blood samples on ice and transferred them to the ﬁeld laboratory. Once in the ﬁeld laboratory, we prepared two additional EDTA-treated blood smears for complete
blood cell analysis using a standard two-slide technique (Aird 2010).

Hematologic parameters
The hematological assessment methods and results,
including our new methylene blue staining technique as
well as reticulocyte and Heinz body identi ﬁcation, have been described in detail previously (Fallon et al. 2018). For Fig. 2 Reference capture
locations in South Carolina for
American oystercatcher, black
skimmer, brown pelican, and
great egret
1402 J. A. Fallon et al.

BLSK, BRPE, and GREG, we prepared new methylene
blue-stained blood smears in the ﬁeld after incubating for 20 min (Fallon et al. 2013). We evaluated 1000 erythrocytes under 1000X light microscopy, counting the number of
cells affected by Heinz bodies as well as the number of reticulocytes (Johns et al. 2008). The individual performing these analyses (JAF) was blinded to oiling status, capture location, and results of other analyses.

We determined PCV and hemoglobin (Hb) from hepar-
inized samples within 12 h of collection. Packed cell
volume (%) was calculated using a standard hematocrit
reader following centrifugation at 11,865 × g for 5 min.

Total Hb (g/dl) was quanti ﬁed using a Hemocue Hb Ana-
lyzer Hb201 (Velguth et al. 2010). Red blood cell count (RBC, cells/mm 3) was estimated via standard manual
methodology using a hemocytometer at a commercial
laboratory (Avian and Exotics Clinical Pathology Labora- tory, Wilmington, OH, USA) (Campbell 1995). Individuals performing these analyses were blinded to oiling status, capture location, and results of other analyses. Hematolo- gical results of these parameters in birds from reference sites and birds with visible oiling were ﬁrst reported in Fallon et al. ( 2018), but are reanalyzed here in relation to the current UV oiling assessment.

Statistical analyses
We used SAS software (version 9.3 SAS Institute Inc.,
Cary, NC, USA) for all analyses. Where appropriate, we
evaluated normality and homogeneity of variance using
Shapiro–Wilk and Levene ’s tests, respectively. We used univariate statistical tests for physiological variable ana- lyses, as this dataset contained missing values for one or more values in several birds (for more details, see Fallon et al. 2018). To account for the lack of independence of physiological responses compared in our univariate models, we applied a conservative α ≤ 0.01 to assess statistical sig- niﬁcance in these models, while also noting cases where α > 0.01 and α ≤ 0.05.

To determine the utility of UV light assessment as a tool to identify birds with small amounts of oil on the plumage that would otherwise be missed by visual oiling assessment, we used McNemar ’s exact test to compare the number of
birds with visible oil to the number of birds with UV oiling from areas affected by the Deepwater Horizon spill within each species. Additionally, we calculated the number of birds that increased one or more category in oiling severity under the application of UV light (e.g., a bird that was categorized as light oiling under visual assessment appeared as moderate oiling under UV assessment) and compared the effect size of this change in severity using Cliff ’s delta (Cliff 1993, Romano et al. 2006, Macbeth et al. 2011).

Cliff’s delta is a measure of the degree of overlap between two populations, and ranges from −1t o +1, with ±0.147
representing a small effect (percent of non-overlap is

14.7%), ±0.33 representing a moderate effect (percent of non-overlap is 33%), and ≥±0.474 representing a large
effect (percent of non-overlap is 47.4% (Cohen 1988).

To determine whether UV oiling assessment improved
detection of birds experiencing adverse clinical signs
compared to those detected through visual assessment
alone, we ﬁrst determined the effects of UV-detectable
oiling on Heinz body formation, reticulocytes, PCV, Hb, and RBC using Kruskal –Wallis tests for each species with subsequent post-hoc analysis (SAS Multtest procedure, Sas Institute Inc 2011). Additionally, we used Mann –Whitney tests to compare physiologic parameters (Heinz bodies,
reticulocytes, PCV, and Hb) from birds with visible oiling to the subset of birds that had no evidence of visible oiling but tested positive for oiling under UV light. Because we had physiological data on a limited number of birds with UV oil but no visible oil, we pooled species for this analysis (Heinz bodies: BLSK n = 18, BRPE n = 8, GREG n = 5
[n = 31 total]; reticulocytes: BLSK n = 18, BRPE n = 8, GREG n
= 5, [ n = 31 total]; PCV: BLSK n = 19, BRPE
n = 8, GREG n = 7, [ n = 34 total]; Hb: BLSK n = 11,
BRPE n = 6, GREG n = 7, [ n = 24 total]).

Results
UV oiling assessment
From our sample of 705 birds from areas impacted by the Deepwater Horizon spill, we identi ﬁed 138 birds with evi- dence of visible oiling. However, the number of oiled birds from the same sample population increased by 259 indivi- duals to 397 birds once we viewed them under UV light.

Therefore, use of UV light increased the overall percentage of oiled birds in our sample population from 19.6 to 56.3% (Table 1, Fig. 3). Importantly, improved detection with the aid of a UV light occurred in all ﬁve species (Table 1, Table 1 Number of individual black skimmer (BLSK), brown pelican (BRPE), clapper rail (CLRA), great egret (GREG), and seaside sparrow (SESP) from areas affected by the Deepwater Horizon oil spill with McNemar ’s test comparing visible oiling and UV ﬂuorescence (*statistical signi ﬁcance)
Total ( N) Visible oil UV oil Chi
2 p value
BLSK 120 47 92 45.00 <0.001*
BRPE 66 21 35 14.00 <0.001*
CLRA 100 14 82 65.06 <0.001*
GREG 54 38 46 8.00 0.005*
SESP 365 18 142 142.00 0.001*
Total 705 138 397
Ultraviolet-assisted oiling assessment improves detection of oiled birds experiencing clinical signs of. . . 1403 Fig. 3). Additionally, we found evidence that the qualitative categorization of oiling severity increased when we eval- uated birds under UV light; 40% of birds increased by at least one category (e.g., an increase from lightly to mod- erately oiled) after using UV compared to a standard visual exam (Fig. 4). Cliff ’s delta analysis revealed a moderate effect size on oiling severity with UV evaluation (delta =

0.288). No BLSK ( n = 87), BRPE ( n = 39), or SESP ( n = 55) from reference locations were found to have oil on their plumage either by visual or UV assessment. We found no
CPRL ( n = 30) from reference sites with oil on standard visual assessment, but one individual was found to have trace amounts under UV assessment. In contrast, of 47
GREG from reference sites, 7 individuals had evidence of trace visible oil and 27 had trace or light UV oil.

Physiological correlates of UV oiling
The physiological responses associated with visible oiling were originally reported elsewhere (Fallon et al. 2018).

Here, we focus on comparing the physiological responses detectable based on the two oiling assesment protocols. We found signi ﬁcantly more Heinz bodies and reticulocytes in BLSK, BRPE, and GREG with UV oiling compared to
reference populations (Table 2). Additionally, we found signiﬁcantly lower PCV and Hb in BRPE and GREG, as
well as decreased RBC in GREG with UV oiling compared
to reference populations (Table 2). Based on visual com- parison of statistical outcomes of our previous study and the current study, we found that the effect of oiling on Heinz body formation, reticulocytes, PCV, Hb, and RBC counts
was similar for both visual (data from Fallon et al. 2018) and UV assessment techniques (Table 3). Additionally, we found no signiﬁcant difference between the mean number of Heinz bodies, reticulocytes, PCV, or Hb between birds that had only UV oiling and birds with oil apparent on both
visual and UV oiling assessment (Table 4).

Discussion
It is important to understand the extent of exposure and injury to birds and other wildlife during oil spill events to develop an accurate damage assessment. While there were thousands of dead birds found in the weeks following the Deepwater Horizon spill, there were many more that were likely exposed to oil but did not immediately succumb
(Peterson et al. 2003; USFWS 2011). We hypothesized that the use of hand-held UV lights could enhance the sensitivity of visible oiling assessments, because even trace amounts of oil have been shown to ﬂuoresce (Chase et al. 2005). To test this, we evaluated 705 individuals from sites affected by the Deepwater Horizon oil spill with both visual and UV
assessment. Ultraviolet assessment identi ﬁed oiling on 259 individual birds (a 97% increase in detection) that appeared to be oil-free on initial visual examination. Ultraviolet assessment resulted in a signi ﬁcant increase in the number of individuals determined to be oiled in all species, although this effect was least pronounced in GREG (Table 1, Fig. 3).

Adult GREG have exclusively white plumage, which likely makes even trace amounts of oil more apparent on visual exam. Additionally, we found that UV assessment revealed that birds had more extensive exposure than was apparent on visual assessment, with 40% of birds increasing by at least one category of oiling severity after application of the UV light (Fig. 4). Cliff ’s delta analysis con ﬁrmed that this effect size was statistically signi ﬁcant. Together, these ﬁndings suggest that UV assessment can more accurately
determine the number and severity of birds exposed to oil Fig. 3 Percent of black skimmer (BLSK), brown pelican (BRPE), clapper rail (CLRA), great egret (GREG), and seaside sparrow (SESP) in areas of potential impact from the Deepwater Horizon oil spill with visible oiling and oil detected under UV ﬂuorescence. Asterisks indicate statistically signi ﬁcant difference ( p < 0.05) between visible and UV detection techniques
Fig. 4 Severity of visible oiling (none is 0% of plumage affected with UV oiling, trace <5% plumage affected, light 6 –20% plumage affec- ted, moderate 21 –40% plumage affected or heavy >40% plumage affected) and oil detected under ultraviolet ﬂuorescence in birds from areas affected by the Deepwater Horizon spill
1404 J. A. Fallon et al.
during spill events compared to visual assessment without the aid of UV light.

We found that UV-oiled birds were experiencing adverse
effects similar to those we had observed in our prior visual assessment (Fallon et al. 2018). Birds with small amounts of oil on their plumage as determined by UV evaluation had hematological changes consistent with oxidative injury to red blood cells (Tables 2, 3). The presence of Heinz bodies combined with increased reticulocytes found in oiled
BLSK, BRPE, and GREG with UV oiling suggests that this
method can be used to detect birds with modest oiling that may be experiencing sublethal physiological injury. Addi- tionally, BRPE and GREG from impacted sites had
decreased PCV and Hb. These three features — presence of Heinz bodies, decreased PCV or Hb, and increased reticu- locytes— are indicative of oxidative injury, anemia, and a physiological regenerative response. This physiologic cas- cade decreases oxygen availability to tissues (Latimer et al. 2003) which can induce muscle fatigue, lethargy, decreased energy availability for metabolic processes, and adversely affect reproduction (Butler et al. 1986; Piersma et al. 1996; Walton et al. 1997; Ots et al. 1998; Hylton et al. 2006).

These physiological changes have implications for survival and ﬁtness, suggesting that sublethal physiological injury associated with modest oil exposure may have important
negative long-term repercussions for individuals. Although there is no clearly established threshold for what degree of reduced erythrocyte volume leads to decreased survival, anemia in oiled birds at admission to rehabilitation facilities is correlated with higher mortality rates (Duerr et al. 2016).

Our results suggest that UV assessments can be useful in identifying birds with very small amounts of oil that also have experienced adverse effects, and that these hematolo- gical changes mirror those found with visible oiling (Fallon et al. 2018).

Although all BLSK, BRPE, and SESP and all but one
CPRL from reference sites had no evidence of visual or UV oil on their plumage, GREG appeared to be at increased risk of oil exposure in our reference sites. Of 47 GREG from reference sites evaluated by both visual and UV assessment, 7 birds (15%) had trace visual oiling and 27 (57%) had trace (n = 26) or light ( n = 1) UV oiling. Of our study species, GREG are the only species with exclusively white plumage, which may make small amounts of oil more easily dis-
cernible. Additionally, this species is unique among those in this study, as it is a wading bird that spends a great deal of foraging time standing or slowly wading through water, and frequents man-made drainage ponds and pooled, standing
water from residential, agricultural, or industrial run-off which may contain petroleum waste (Trail 2006; McCrim-
mon et al. 2011). Consistent with their exposure, this was the only species in which Heinz bodies were identi ﬁed in the reference population. Our results suggest that further Table 2 Summary of the response of birds exposed to oil based on UV oiling assessment from the Deepwater Horizon oil spill

BLSK BRPE GREG
Variable Mean
reference
Mean
impacted
p value Percent
difference
Mean
reference
Mean
impacted
p value Percent
difference
Mean
reference
Mean
impacted
p value Percent
difference
Heinz bodies 0 9.34 <0.001* N/A 0 1.64 0.028** N/A 0.87 8.1 <0.001* 96.44% Reticulocytes 53.6 67.3 0.004* 25.6% 44.5 65.6 <0.001* 47.38% 54.3 69.0 0.007* 27.11% PCV 44.7 43.1 0.137 −3.6% 50.2 43.3 <0.001* −13.83% 46.1 37.3 <0.001* −19.02% Hemoglobin 17.0 16.8 0.841 −1.1% 17.4 19.2 0.006* −10.29% 15.9 13.9 <0.001* −12.61% RBC 2.71 2.64 0.905 −2.6% 2.89 2.85 0.791 −1.55% 2.63 2.43 0.012** −7.77% Kruskal–Wallis results are reported for Heinz bodies (cells with Heinz bodies/1000 erythrocytes), reticulocytes (%), PCV (%), hemoglobin (g/dl), and RBC (c ells/mm3) found in black skimmers (BLSK), brown pelicans (BRPE), and great egrets (GREG). Percent differences calculated from the mean values from birds from reference areas (BLSK n = 57, BRPE n = 32, GREG n = 46) and birds from Deepwater Horizon affected (impacted) sites with UV detected oil (BLSK n = 51, BRPE n = 44, GREG n = 51) relative to the reference mean. Asterisk represents signi ﬁcance ( p ≤

0.01) and **indicates marginal signi ﬁcance (0.01 < p ≤ 0.05). N/A indicates that results were not determined for this variable in a particular bird except one GREG. Mean reference results previously published in Fallon et al. 2018)
Ultraviolet-assisted oiling assessment improves detection of oiled birds experiencing clinical signs of. . . 1405 investigation into the frequency of exposure to petroleum products in this species is warranted.

There are several limitations to consider when incor-
porating UV light assessment during oil spill events. First, the individual bird must be evaluated under minimal natural light, which is cumbersome with large birds. Second,
although application of UV light increased the detection of oiled birds, the majority of birds that appeared to be oil-free on visual examination that were determined to be oiled
under UV light application had only trace or light amounts of oil on their plumage (5 –20% of plumage affected).

Because of this, the severity of hematologic changes in the UV-oiled population of birds was similar to that of visibly oiled birds (Table 3, Fig. 4). Thus, UV assessment proved useful for enhancing detection of birds exposed to oil, but did not increase detection of birds experiencing clinical signs of anemia compared to standard visual assessment.

Finally, there is the possibility of false positive ﬂuorescence with naturally occurring oils. Further work in an experi- mental setting may help determine the frequency of false positive results.

In summary, our results demonstrate that UV assessment
can identify small amounts of oil present on birds that appear oil-free on visual exam. Additionally, UV light
allowed detection of oiled feathers over a larger proportion of surface area on individuals than can be seen on visual exam. Therefore, UV assessment of individual birds could be considered as an additional tool following both large and small oil spill events to help formulate a more complete damage assessment. This technique may be most useful to categorize birds with trace oiling that would otherwise be missed on visual exam, particularly in birds with dark
plumage. Further, UV-oiled birds exposed to the Deepwater Horizon spill had evidence of oxidative injury to ery-
throcytes, decreased numbers of erythrocytes in circulation, and evidence of an erythrocytic regenerative response,
similar to birds with visible oiling. These changes are consistent with formation of Heinz bodies and oxidative hemolytic anemia, a pathological abnormality caused by
exposure to oil.

Acknowledgements The authors thank Pete Tuttle and Michael Hooper, for scienti ﬁc advising, technical support, and assistance dur- ing this study. We are indebted to the many dedicated people who assisted with the collection of the avian samples, including Lisa Eggert who helped coordinate the collection of the BLSK samples; Lucas Savoy who coordinated the collection of CLRA, Dr. Peter Frederick and Jason Fidorra who led the collection of the GREG samples; Mike Yates and Jim Dayton who coordinated sample collection from BRPE.

Additionally, BLSK, BRPE, GREG samples were processed in BRI ’s ﬁeld laboratory by a dedicated team who provided excellent assistance, including Dr. Michelle Walsh, Dr. Lee Friedman, Ruth Valentine, Judi Ellal, Michelle Brown, Alishia Zyer, Tim Watson, and Ken Weber.

Jeff Walters, Eric Hallerman, and Todd Katzner provided helpful comments that improved the manuscript. Any use of trade, ﬁrm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Compliance with ethical standards
Conﬂict of interest The authors declare that they have no con ﬂict of interest.

Ethical approval The procedures involving animals were conducted by Biodiversity Research Institute with approval from the U.S. Fish and Table 3 Summary of results
from Kruskal –Wallis analysis of
oiled birds as determined by
visual assessment under natural
lighting conditions (data from
Fallon et al. 2018) compared to
reference populations and UV-
assisted assessment compared to
reference populations
Heinz Bodies Reticulocytes PCV Hb RBC
BLSK
UV oiled <0.001 0.004 0.137 0.841 0.905
Visibly oiled <0.001 0.004 0.164 0.876 0.613
BRPE
UV oiled 0.028 <0.001 <0.001 0.006 0.791
Visibly oiled 0.024 <0.001 <0.001 0.002 0.561
GREG
UV oiled <0.001 0.007 <0.001 <0.001 0.012
Visibly oiled 0.003 0.010 <0.001 <0.001 0.003
Response variables were Heinz bodies (cells with Heinz bodies/1000 erythrocytes), reticulocytes (%), packed cell volume (PCV, %), hemoglobin (Hb, g/dl), and red blood cell count (RBC, cells/mm 3) found in
black skimmers (BLSK), brown pelicans (BRPE), and great egrets (GREG) Table 4 Mann–Whitney comparison of mean number of Heinz bodies (number of cells/1000 erythrocytes), reticulocytes (%), packed cell volume (PCV, %), and hemoglobin (g/dl) between birds (pooled species including black skimmers, brown pelicans, and great egrets) that tested positive for oiling under both UV and natural (visible) light versus those that tested positive under UV light only from sites impacted by the Deepwater Horizon oil spill
Visible and UV oil UV oil only
Variable n mean (±SE) n mean (±SE) p value
Heinz bodies 79 8.22 (1.99) 31 2.87 (1.58) 0.355
Reticulocytes 79 69.08 (2.10) 31 64.84 (3.09) 0.597
PCV 78 40.40 (0.57) 34 40.24 (0.94) 0.730
Hemoglobin 73 14.88 (0.38) 24 15.40 (0.53) 0.320
1406 J. A. Fallon et al.

Wildlife Service. All applicable international, national, and/or insti- tutional guidelines for the care and use of animals were followed.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional af ﬁliations.

References
Alonso-Alvarez C, Munilla I, López M, Velando A (2007) Sublethal toxicity of the Prestige oil spill on yellow-legged gulls. Environ Intern 33:773 –781
Aird B (2010) Clinical and hematologic manifestations of anemia. In:

Feldman BF, Zinkl JG, Jain NC (eds) Schalm ’s veterinary hematology, 5th edn. Blackwell Publishing Ltd, Ames, Iowa, USA, p 140 –142
Brekke C, Solberg AHS (2005) Oil spill detection by satellite remote sensing. Proc Spie 95:1 –13
Briggs KT, Yoshida SH, Gershwin ME (1996) The in ﬂuence of pet- rochemicals and stress on the immune system of seabirds. Regul Toxicol Pharmacol 23:145 –55
Burlamacchi P, Cecchi G, Mazzinghi P, Pantani L (1983) Performance evaluation of UV sources for lidar ﬂuorosensing of oil ﬁlms. Appl Opt 22:48 –53
Butler RG, Peakall DB, Leighton FA, Borthwick J, Harmon RS (1986) Effects of crude oil exposure on standard metabolic rate of Leach’s storm-petrel. Condor 88:248 –249
Campbell TW (1995) Avian hematology and cytology. Iowa State University Press, Ames, Iowa, USA
Chase CR, Van Bibber S, Muniz TP (2005) Development of a non- contact oil spill detection system. Oceans 2:1352 –1357 Cliff N (1993) Dominance statistics: ordinal analyses to answer ordinal questions. Psychol Bull 114:494 –509
Cohen J (1988) Statistical power analysis for the behavioral sciences, 2nd edn. Hillsdate, New Jersey, USA
Colligan TH, LaManna JM (1993) Using ultraviolet light to investigate petroleum-contaminated soil. Remediat J 3:193 –201
Crozier GE, Gawlik DE (2003) The use of decoys as a research tool for attracting wading birds. J Field Ornithol 74:53 –58 Duerr RS, Ziccardi MH, Massey JG (2016) Mortality during treatment:
factors affecting the survival of oiled, rehabilitated Common Murres ( Uria aalge ). J Wildl Dis 52:495 –505
Eppley ZA, Rubega MA (1990) Indirect effects of an oil spill:
reproductive failure in a population of South Polar skuas fol- lowing the ‘Bahia Paraiso ’oil spill in Antarctica. Mar Ecol Prog Ser 67:1 –6
Esler D, Schmutz JA, Jarvis RL, Mulcahy DM (2000) Winter survival of adult female harlequin ducks in relation to history of con- tamination by the Exxon Valdez oil spill J Wildl Manag
64:839–847
Fallon JA, Hopkins WA, Fox L (2013) A practical quanti ﬁcation method for Heinz bodies in birds applicable to rapid response ﬁeld scenarios. Environ Toxicol Chem 32:401 –405
Fallon JA, Smith EP, Schoch N, Paruk JD, Adams EA, Evers DC, Jodice PG, Perkins C, Schulte S, Hopkins WA (2018) Hemato- logical indices of injury to lightly oiled birds from the Deepwater Horizon oil spill. Environ Toxicol Chem 37:451 –461
Fingas M, Brown CE (2014) Review of oil spill remote sensing. Mar Pollut Bull 83:9 –23
Fingas M, Brown CE (2013) Detection of oil in ice and snow. J Mar Sci Eng 1:10 –20
Fingas M, Brown C (2000) A review of the status of advanced tech- nologies for the detection of oil in and with ice. Spill Sci Technol Bull 6:295 –302
Fingas MF, Brown CE (1997) Review of oil spill remote sensing. Spill Sci Technol Bull 4:199 –208
Fry M, Lowenstine LJ (1985) Pathology of Common Murres and Cassin’s Auklets exposed to oil. Arch Environ Contam Toxicol 14:725–737
Fry DM, Swenson J, Addiego LA, Grau CR, Kangt A (1986) Reduced reproduction of wedge tailed shearwaters exposed to weathered Santa Barbara crude oil. Arch Environ Contam Toxicol
15:453–463
Giese M, Goldsworthy SD, Gales R, Brothers N, Hamill J (2000) Effects of the Iron Baron oil spill on little penguins ( Eudyptula minor): breeding success of rehabilitated oiled birds. Wildl Res 27:583–591
Gochfeld M, Burger J, Lefevre KL (2020) Black Skimmer ( Rynchops niger), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https:// doi.org/10.2173/bow.blkski.01
Golet GH, Seiser PE, McGuire AD, Roby DD, Fischer JB, Kuletz KL, Irons DB, Dean TA, Jewett SC, Newman SH (2002) Long-term direct and indirect effects of the Exxon Valdez oil spill on pigeon guillemots in Prince William Sound, Alaska. Mar Ecol Prog Ser 241:287–304
Harr KE, Cunningham FL, Pritsos CA, Pritsos KL, Muthumalage T, Dorr BS, Horak KE, Hanson-Dorr KC, Dean KM, Cacela D,
McFadden AK (2017) Weathered MC252 crude oil-induced
anemia and abnormal erythroid morphology in double-crested cormorants ( Phalacrocorax auritus ) with light microscopic and ultrastructural description of Heinz bodies. Ecotox Environ Saf 146:29–39
Herring G, Gawlik DE, Beerens JM (2008) Evaluating two new methods for capturing large wetland birds. J Field Ornithol 79:102–110
Hylton RA, Frederick PC, De La Fuente TE, Spalding MG (2006) Effects of nestling health on post ﬂedging survival of wood storks.

Condor 108:97 –106
Iverson SA, Esler D (2010) Harlequin Duck population injury and recovery dynamics following the 1989 Exxon Valdez oil spill.

Ecol Appl 20:1993 –2006
Jha MN, Levy J, Gao Y (2008) Advances in remote sensing for oil spill disaster management: state-of-the-art sensors technology for oil spill surveillance. Sensors 8:236 –255
Johns JL, Shooshtari MP, Christopher MM (2008) Development of a technique for quanti ﬁcation of reticulocytes and assessment of erythrocyte regenerative capacity in birds. Am J Vet Res 89:1067–1072
Latimer KS, Mahaffey EA, Prasse KW (2003) Duncan and Prasse ’s veterinary laboratory medicine: clinical pathology, 4th edn.

Blackwell Publishing, Ames, Iowa, USA
Leighton FA (1986) Clinical gross and histological ﬁndings in Herring Gulls and Atlantic Puf ﬁns that ingested Prudhoe Bay oil. Vet Pathol 23:254 –263
Leighton FA (1995) The toxicity of petroleum oils to birds: an over- view. In: Frink L, Weir KB, Smith C (eds) Wildlife and oil spills.

Tri-state Bird Rescue and Research, Inc., Newark, Delaware, USA, p 10 –22
Leighton FA, Lee YZ, Rahimtula AD, O ’Brien PJ, Peakall DB (1985) Biochemical and functional disturbances in red blood cells of herring gulls ingesting Prudhoe Bay crude oil. Toxicol Appl Pharmacol 81:25 –31
Leighton FA, Peakall DB, Butler RG (1983) Heinz-body hemolytic anemia from the ingestion of crude oil: a primary toxic effect in marine birds. Science 4599:871 –873
Macbeth G, Razumiejczyk E, Ledesma RD (2011) Cliff ’s delta cal- culator: a non-parametric effect size program for two groups of observations. Univ Psychol 10:545 –555
McCrimmon, DA, Ogden JC, Bancroft GT, Martínez-Vilalta A, Motis A, Kirwan GM, Boesman PFD (2020) Great Egret (A rdea alba), version 1.0. In Birds of the World (S. M. Billerman, Editor).

Ultraviolet-assisted oiling assessment improves detection of oiled birds experiencing clinical signs of. . . 1407 Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10. 2173/bow.greegr.01
Mills JA, Ryder JP (1979) Trap for capturing shore and seabirds. Bird Band 50:121 –123
Munilla I, Arcos JM, Oro D, Álvarez D, Leyenda PM, Velando A (2011) Mass peak mortality of seabirds in the aftermath of the Prestige oil spill. Ecosphere 2:1 –14
Ots I, Murumägi A, Horak P (1998) Haematological health state indices of reproducing great tits: methodology and sources of natural variation. Funct Ecol 12:700 –707
Perkins M, King SL, Linscombe J (2010) Effectiveness of capture techniques for rails in emergent marsh and agricultural wetlands.

Waterbirds 33:376 –380
Peterson CH, Rice SD, Short JW, Esler D, Bodkin JL, Ballachey BE, Irons DB (2003) Long term ecosystem response to the Exxon Valdez oil spill. Science 302:2082 –2086
Piatt JF, Lensink CJ, Butler W, Kendziorik M, Nysewander DR (1990) Immediate impact of the Exxon Valdez oil spill on marine birds.

Auk 107:387 –97
Piersma T, Everaarts TM, Jukema J (1996) Build-up of red blood cells in refueling bar-tailed godwits in relation to individual migratory quality Condor 98:363 –370
Post W, Greenlaw JS (2020) Seaside Sparrow ( Ammospiza maritima), version 1.0. In Birds of the World (P. G. Rodewald, Editor).

Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10. 2173/bow.seaspa.01
Romano J, Kromrey JD, Coraggio J, Skowronek J, Devine L (2006) Exploring methods for evaluating group differences on the NSSE and other surveys: are the t-test and Cohen ’s d indices the most appropriate choices? In: Proceedings of the Annual Meeting of the Southern Association for Institutional Research, Arlington, VA, USA, pp 14 –17
Rush SA, Gaines KF, Eddleman WR, Conway CJ (2020) Clapper Rail (Rallus crepitans ), version 1.0. In Birds of the World (P. G.

Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.clarai11.01
SAS Institute Inc (2011) Base SAS
® 9.3 procedures guide. SAS
Institute Inc, Cary, NC
Seiser PE, Duffy LK, McGuire AD, Roby DD, Golet GH, Litzow MA (2000) Comparison of pigeon guillemot, Cepphus columba , blood parameters from oiled and unoiled areas of Alaska eight years after the Exxon Valdez oil spill. Mar Pollut Bull 40:152–164
Shields M (2020) Brown Pelican ( Pelecanus occidentalis), version 1.0.

In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow. brnpel.01
Trail PW (2006) Avian mortality at oil pits in the United States: a review of the problem and efforts for its solution. Environ Manag 38:532–544
Troisi GM, Borjesson L, Bexton S, Robinson I (2007) Biomarkers of polycyclic aromatic hydrocarbon (PAH)-associated hemolytic anemia in oiled wildlife. Environ Res 105:324 –329
Trust KA, Esler D, Woodin BR, Stegeman JJ (2000) Cytochrome P450 1A induction in sea ducks inhabiting nearshore areas of Prince William Sound, Alaska. Mar Pollut Bull 40:397 –403 [USFWS] US Fish and Wildlife Service (2011) Deepwater Horizon bird impact data from the DOI-ERDC NRDA Database 12 May 2011. http://www.fws.gov/home/dhoilspill/pdfs/Bird%20Data% 20Species%20Spreadsheet%2005122011.pdf. Accessed 4 Aug
2012
Vieira BP, Furness RW, Nager RG (2018) What do we know about Black Skimmers? review on its annual-cycle and life-history main events. Ardea 106:119 –130
Velguth KE, Payton ME, Hoover JP (2010) Relationship of hemo- globin concentration to packed cell volume in avian blood sam- ples. J Avian Med Surg 24:115 –121
Yamato O, IKoto I, Maede Y (1996) Hemolytic anemia in wild sea- ducks caused by marine oil pollution. J Wildl Dis 32:381 –384 Walton RM, Brown DE, Hamar DW, Meador VP, Horn JW, Thrall MA (1997) Mechanisms of echinocytosis induced by Crotalus atrox venom. Vet Pathol 34:442 –449
1408 J. A. Fallon et al.

City of Long Beach Oil and Gas Extraction
April 1, 2022
This summary report describes oil and gas extraction activity occurring within the boundaries of the city of Long Beach. See the map in Figure 2 for a visual description of the study area.

Well Status: There are a total of 2,762 operational wells within the city limits of Long Beach.

Active wells account for 71.3%, idle wells for 27.3%, and new wells 1.4%.

Well Type: The majority of wells are oil and gas production wells (2,031). Production from these wells is enhanced via 705 waterflood injection wells.

Location: About half of the operational well count is considered onshore (1,365), and the other half offshore (1,397). For many of the wells on the docks of the Long Beach harbor, the distinction is arbitrary. There are 1,390 operational wells located on the four THUMS/Astronaut Islands.

Figure 1. Chart of CalGEM oil and gas well statuses. The pie chart shows the breakdown of well statuses for operational wells within the boundaries of the city of Long Beach.

Operators: There are 92 individual operators in the City of Long Beach. The majority of wells are operated by subsidiaries of California Resources Corporation; California Resources Long Beach, Inc (88), THUMS Long Beach Co (1,562) and Tidelands Oil Production Co (768). Other operators include Signal Hill Petroleum (93), Synergy Oil &Gas LLC (61) in the Seal Beach field, Warren E&P (42) in the Wilmington Field and The Termo Company (22) in several fields. 1968
754
40 Long Beach Well Status Count
Active
Idle
New
Production: In total, the operational wells within the Long Beach city limits produced a total 893,247 barrels of crude oil/condensate in 2020. Only 16 of the 93 operators with operational wells produced oil in 2020.

Table 1. Production by operator for 2020.

Operator 2020 Production (Bbls)
THUMS Long Beach Co. 6,561,448
Tidelands Oil Production Co. 2,324,338
Signal Hill Petroleum, Inc. 258,010
California Resources Long Beach, Inc. 232,179
Synergy Oil & Gas, LLC 112,622
Warren E&P, Inc. 76,548
E & T Limited Liability Co. 38,498
The Termo Company 35,899
The Lansdale Co. 23,609
Arrowhead Operating, Inc. 8,885
Herley-Kelley LLC 3,983
P&M Oil Company, Inc. 3,920
E & B Natural Resources Management Corporation 3,681
TJ Scott Family Investments, LLC 2,164
S & C Oil Co., Inc. 2,154
Mitchell-Grossu Oil Co. 1,686
Age: The age of the wells vary widely and a distribution is difficult to generate as spud data is sparsely included in CalGEM’s “AllWells” dataset. It is also difficult to pinpoint the oldest well still operating within the city limits, but records dating back to the 1930’s are not uncommon.

Population: There is an estimated 463,569 people living in the City of Long Beach (U.S. Census Bureau. American Community Survey, 5-year, 2013-2019). An estimated 140,138 individuals live within 3,200’ of an operational oil and gas well within the city limits. This is about 30.2% of the population. Of those, 101,498 (72.4%) identify as non-white, including Latina/Hispanic origin. This is slightly higher than the citywide average (71.7% non-white)

Figure 1. Map of Long Beach Oil and Gas Extraction Locations. The map of the City of Long Beach shows the locations of CalGEM’s operational oil and gas wells. _____________________________________________________________________________________ Kyle Ferrar • [email protected] • (O) 415-890-3722 • www.FracTracker.org

PRIMARY AUTHORS
This final recovery plan was prepared by Kelly Hornaday, Ina Pisani, and Betty Warne of our Sacramento Fish and Wildlife Office. Ruth Pratt of the Sacramento Fish and Wildlife Office coordinated preparation of the draft recovery plan and acted as Recovery Team Manager.

We gratefully acknowledge the efforts of the Pacific Coast Western Snowy Plover Recovery Team in preparing this recovery plan. Special acknowledgment is also given to Nadav Nur, Point Reyes Bird Observatory, Stinson Beach, California, for his work on the population viability analysis.
iii

DISCLAIMER
Recovery plans delineate reasonable actions that are believed to be required to recover and/or protect listed species. We, the U.S. Fish and Wildlife Service, publish recovery plans, sometimes preparing them with the assistance of recovery teams, contractors, State agencies, and others. Recovery teams serve as independent advisors to the U.S. Fish and Wildlife Service. Objectives of the recovery plan will be attained and necessary funds made available subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities. Recovery plans do not obligate other parties to undertake specific actions, and may not represent the views or the official positions or approval of any individuals or agencies involved in the recovery plan formulation other than our own. They represent our official position only after they have been signed by the Director, Regional Director, or Operations Manager as approved. Approved recovery plans are subject to modification as dictated by new findings, changes in species status, and the completion of recovery actions.

Literature Citation Should Read As Follows:

U.S. Fish and Wildlife Service. 2007. Recovery Plan for the Pacific Coast Population of the Western Snowy Plover (Charadrius alexandrinus nivosus). In 2 volumes. Sacramento, California. xiv + 751 pages.

An electronic version of this recovery plan also will be made available at http://www.fws.gov/cno/es/recoveryplans.html and
http://endangered.fws.gov/recovery/index.html#plans
iv

ACKNOWLEDGMENTS
The following U.S. Fish and Wildlife Service staff provided valuable review and comments on the recovery plan: John Grettenberger and Martha Jensen, Western Washington Office, Lacey, Washington; Carrie Phillips, Elizabeth Kelly, and Fred Seavey, Newport Fish and Wildlife Office, Newport, Oregon; Jim Watkins, Arcata Fish and Wildlife Office, Arcata, California; Kevin Clark and Gjon Hazard, Carlsbad Fish and Wildlife Office, Carlsbad, California; Steve Henry, Steve Kirkland, and David Pereksta, Ventura Fish and Wildlife Office; Diane Elam, California/Nevada Operations Office, Sacramento, California; and Grant Canterbury, Pacific Regional Office, Portland, Oregon. Robert Mesta, Bureau of Land Management Region 2 Office, Tucson, Arizona also provided valuable review and comments on the recovery plan.

Jennifer Bain, Valary Bloom, Don Hankins, Larry Host, Harry McQuillen, Caroline Prose, Caralee Stevens, Glen Tarr, Kim Turner, Betty Warne, and Dan Welsh of the Sacramento Fish and Wildlife Office, Sacramento, California also assisted in preparation of the final recovery plan.

Maps of snowy plover sites in Appendix L were prepared by Brian Cordone, Cheryl Hickam, and Joni Mitchell, Sacramento Fish and Wildlife Office, Sacramento, California.

The cover illustrations for the front cover and Appendix K are used courtesy of Carleton R. Eyster, Santa Cruz, California.
v

PACIFIC COAST WESTERN SNOWY PLOVER RECOVERY TEAM
Sarah Allen Sean Morton
National Park Service County of Santa Barbara
Point Reyes, California Santa Barbara, California
Tim Burr Martin Nugent
U.S. Department of the Navy Oregon Department of Fish and Wildlife San Diego, California Portland, Oregon
Jeff Chastain Gary Page
C & M Stables Point Reyes Bird Observatory
Florence, Oregon Stinson Beach, California
Janet Didion Kerrie Palermo
California Dept. of Parks and Recreation U.S. Bureau of Land Management Sacramento, California North Bend, Oregon

David Dixon Daniel Pearson
California Dept. of Parks and Recreation Southern California Edison Monterey, California Rosemead, California
Ivette Loredo John Phillips (deceased)
San Francisco Bay National Wildlife Refuge Oregon Parks and Recreation Dept.

Newark, California Coos Bay, Oregon
Richard Griffiths Abby Powell
U.S. Marine Corps U.S.G.S., Biological Resources Division Camp Pendleton, California Fairbanks, Alaska
Jim Heaney Jim Raives
U.S. Bureau of Land Management California Coastal Commission North Bend, Oregon San Francisco, California
William Hornbrook Nancy R. Francine
Fish Phone U.S. Department of the Air Force
Eureka, California Vandenberg Air Force Base, California Tim Jensen Chris Regan
Monterey Peninsula Regional Park District Washington State Parks and Recreation Carmel Valley, California Olympia, Washington
Ron Jurek Scott Richardson (Max Bahn, alternate)
California Department of Fish and Game Washington Department of Fish and Wildlife Sacramento, California Olympia, Washington
Don Klusman Mark Stern
California Assoc. of 4 Wheel Drive Clubs, Inc. Oregon Natural Heritage Program Yuba City, California Portland, Oregon
vi

EXECUTIVE SUMMARY
CURRENT SPECIES STATUS: The Pacific coast population of the western snowy plover (Charadrius alexandrinus nivosus) (western snowy plover) is federally listed as threatened. The current Pacific coast breeding population extends from Damon Point, Washington, south to Bahia Magdalena, Baja California, Mexico (including both Pacific and Gulf of California coasts). The western snowy plover winters mainly in coastal areas from southern Washington to Central America.

HABITAT REQUIREMENTS AND LIMITING FACTORS: The Pacific coast population of the western snowy plover breeds primarily above the high tide line on coastal beaches, sand spits, dune-backed beaches, sparsely-vegetated dunes, beaches at creek and river mouths, and salt pans at lagoons and estuaries.

Less common nesting habitats include bluff-backed beaches, dredged material disposal sites, salt pond levees, dry salt ponds, and river bars. In winter, western snowy plovers are found on many of the beaches used for nesting as well as on beaches where they do not nest, in man-made salt ponds, and on estuarine sand and mud flats.

Habitat degradation caused by human disturbance, urban development, introduced beachgrass (Ammophila spp.), and expanding predator populations have resulted in a decline in active nesting areas and in the size of the breeding and wintering populations.

RECOVERY OBJECTIVE: The primary objective of this recovery plan is to remove the Pacific coast population of the western snowy plover from the List of Endangered and Threatened Wildlife and Plants by: (1) increasing population numbers distributed across the range of the Pacific coast population of the western snowy plover; (2) conducting intensive ongoing management for the species and its habitat and developing mechanisms to ensure management in perpetuity; and (3) monitoring western snowy plover populations and threats to determine success of recovery actions and refine management actions. vii
RECOVERY PRIORITY: 3C, per criteria published by Federal Register Notice (U.S. Fish and Wildlife Service 1983).

RECOVERY CRITERIA: The Pacific coast population of the western snowy plover will be considered for delisting when the following criteria have been met:

1. An average of 3,000 breeding adults has been maintained for 10 years, distributed among 6 recovery units as follows: Washington and Oregon, 250 breeding adults; Del Norte to Mendocino Counties, California, 150 breeding adults; San Francisco Bay, California, 500 breeding adults; Sonoma to Monterey Counties, California, 400 breeding adults; San Luis Obispo to Ventura Counties, California, 1,200 breeding adults; and Los Angeles to San Diego Counties, California, 500 breeding adults. This criterion also includes implementing monitoring of site-specific threats, incorporation of management activities into management plans to ameliorate or eliminate those threats, completion of research necessary to modify management and monitoring actions, and development of a post-delisting monitoring plan.

2. A yearly average productivity of at least one (1.0) fledged chick per male has been maintained in each recovery unit in the last 5 years prior to delisting.

3. Mechanisms have been developed and implemented to assure long-term protection and management of breeding, wintering, and migration areas to maintain the subpopulation sizes and average productivity specified in Criteria 1 and 2. These mechanisms include establishment of recovery unit working groups, development and implementation of participation plans, development and implementation of management plans for Federal and State lands, protection and management of private lands, and public outreach and education.

ACTIONS NEEDED:

1. Monitor breeding and wintering populations and habitats of the Pacific coast population of the western snowy plover to determine progress of recovery actions to maximize survival and productivity.
viii

2. Manage breeding and wintering habitat of the Pacific coast population of the western snowy plover to ameliorate or eliminate threats and maximize survival and productivity.

3. Develop mechanisms for long-term management and protection of western snowy plovers and their breeding and wintering habitat.

4. Conduct scientific investigations that facilitate the recovery of the western snowy plover.

5. Conduct public information and education programs about the western snowy plover.

6. Review progress towards recovery of the western snowy plover and revise recovery efforts, as appropriate.

7. Dedicate U.S. Fish and Wildlife Service staff to allow the Arcata Fish and Wildlife Office to coordinate western snowy plover recovery implementation.

8. Establish an international conservation program with the government of Mexico to protect western snowy plovers and their breeding and wintering locations in Mexico.

Appendices B and C address Actions 1 and 2, providing site-specific recommendations for breeding numbers and management actions. Appendix J addresses Action 1, providing guidelines for monitoring western snowy plovers during the breeding and wintering seasons. Appendix K addresses Action 5, providing a public information and education plan.

ESTIMATED COST OF RECOVERY: $149,946,000 plus additional costs that cannot be estimated at this time.

DATE OF RECOVERY: Delisting could occur by 2047 if the recovery criteria above have been met.
ix
x

TABLE OF CONTENTS
I. INTRODUCTION ............................................... 1 A. DESCRIPTION AND TAXONOMY ......................... 4 B. LIFE HISTORY AND ECOLOGY ........................... 7

1. Breeding .......................................... 7 a. Population Size and Distribution ................. 8 b. Arrival and Courtship ......................... 10
c. Duration of Breeding Season ................... 11
d. Nests and Nest Sites .......................... 11
e. Egg Laying, Clutch Size, and Incubation .......... 12 f. Clutch Hatching Success ....................... 14
g. Brood-rearing ............................... 14
h. Fledging success ............................. 15
i. Productivity ................................. 16
j. Survival .................................... 17

2. Feeding Habitat and Habits ........................... 17

3. Migration ........................................ 18

4. Wintering ........................................ 19 a. Distribution and Abundance .................... 19
b. Site Fidelity ................................. 20
c. Behavior ................................... 20
C. POPULATION STATUS AND TRENDS ..................... 21

1. Historical Trends ................................... 21 a. Washington Coast ............................ 21
i. Grays Harbor County .................... 21
ii. Pacific County ........................ 22
b. Oregon Coast ............................... 24
c. California Coast ............................. 27
i. Coastwide Perspective ................... 27
ii. Regional Perspective ................... 29

2. Current Breeding Distribution ........................ 32

3. Habitat Carrying Capacity ........................... 32 D. REASONS FOR DECLINE AND CONTINUING THREATS .... 33
xi

1. The Present or Threatened Destruction, Modification, or Curtailment of Habitat or Range ................... 33 a. Shoreline Stabilization and Development .......... 33 b. Resource Extraction .......................... 34
i. Sand Removal and Beach Nourishment ..... 34
ii. Dredging and Disposal of Dredged
Materials ......................... 36
iii. Driftwood Removal .................... 36
iv. Beach Fires and Camping ............... 37
v. Watercourse Diversion, Impoundment, or
Stabilization ....................... 37
vi. Operation of Salt Ponds ................. 38
c. Encroachment of Introduced Beachgrass and Other
Nonnative Vegetation ..................... 38
d. Habitat Conversion for Other Special Status
Species ................................. 42

2. Overutilization for Commercial, Recreational, Scientific, or Education Purposes ............................. 45

3. Disease or Predation ................................ 47

4. The Inadequacy of Existing Regulatory Mechanisms ...... 55

5. Other Natural or Manmade Factors Affecting Their
Continued Existence ............................ 56
a. Natural Events ............................... 56
b. Disturbance of Breeding Plovers by Humans and
Domestic Animals ........................ 57
i. Pedestrians ............................ 58
ii. Dogs ................................ 63
iii. Motorized Vehicles .................... 65
iv. Beach Cleaning ....................... 67
v. Equestrian Traffic ...................... 67
vi. Fishing .............................. 68
vii. Fireworks ........................... 69
viii. Kite Flying and Model Airplanes ........ 70
ix. Aircraft Overflights .................... 70
x. Special Events ......................... 71
xii
xi. Coastal Access ........................ 72
xii. Livestock Grazing ..................... 72
c. Oil Spills ................................... 72
d. Contaminants ............................... 75
e. Litter, Garbage, and Debris ..................... 76 f. Water Quality and Urban Run-off ................ 77 g. Management for Other Special Status Species ...... 78 E. IMPLICATIONS FOR THE COASTAL BEACH-DUNE
ECOSYSTEM ....................................... 78

1. Description of Coastal Beach-Dune Ecosystem ........... 79

2. Sensitive Species of the Coastal Beach-Dune Ecosystem ... 81 F. CONSERVATION EFFORTS .............................. 83

1. Conservation Planning on Federal and State Lands ........ 84

2. Conservation Efforts on Federal and State Lands ......... 87 a. Exclosures, Symbolic Fencing, and Signs ......... 87 b. Law Enforcement ............................ 90
c. Predator Control ............................. 90
d. European Beachgrass Control ................... 93
e. Off-Road Vehicle Restrictions and Management .... 99 f. Population Monitoring ........................ 101
g. Salt Pond Management ....................... 102
h. Habitat Acquisition .......................... 103
i. Use of Volunteers ........................... 103
j. Public Outreach and Education ................. 104 k. Section 6 Cooperative Agreements .............. 105

3. Conservation Efforts on Private Lands ................. 106

4. Federal Regulatory Program ......................... 106 a. Critical Habitat ............................. 106
b. Section 9 Take Prohibitions ................... 110 c. Section 10 Permits .......................... 111
d. Section 7 Requirements and Consultations ....... 112 e. Other Federal Regulations, Executive Orders, and
Agreements ............................ 112

5. State Regulatory Protection, Policies, and Agreements .... 115 xiii

6. Consultations, Habitat Conservation Plans, and Other Regulatory Actions ............................ 119

7. Regulatory Protection and Policies of Local Governments ............................................ 125

8. Interagency Coordination ........................... 126 II. RECOVERY ................................................. 129 A. RECOVERY STRATEGY ............................... 129

1. Recovery Strategy Components ...................... 129

2. Roles of Federal, State, Local, and Private Sectors ....... 132 a. Role of Federal Lands ........................ 132
b. Role of State Lands .......................... 133
c. Roles of State and Local Governments ........... 133 d. Role of Municipal Lands ..................... 134
e. Role of Private Lands ........................ 134

3. Conservation Tools and Strategies ................... 134

4. Funding Sources ................................. 134

5. Coordination, Participation, and Working Groups ........ 136 B. RECOVERY UNITS .................................... 137 C. RECOVERY GOALS AND OBJECTIVES .................. 140 D. RECOVERY CRITERIA ................................. 141 E. RELATIONSHIP OF RECOVERY ACTIONS AND CRITERIA
TO THREATS ...................................... 147
III. NARRATIVE OUTLINE OF RECOVERY ACTIONS .............. 155 IV. IMPLEMENTATION SCHEDULE .............................. 213 V. REFERENCES ............................................... 239 A. Literature Cited ........................................ 239 B. Personal Communications ................................ 266 C. In Litt. References ...................................... 268 xiv

LIST OF APPENDICES
(See Volume 2)
Appendix A. Locations of Current or Historical Snowy Plover Breeding and Wintering Areas .................................... A-1 Appendix B. Information on Snowy Plover Breeding and Wintering Locations .................................................. B-1
Appendix C. Summary of Current and Additional Needed Management Activities for Snowy Plover Breeding and Wintering Locations .................................................. C-1
Appendix D. Population Viability Analysis for Pacific Coast Snowy Plovers D-1 Appendix E. Associated Sensitive Species of the Coastal Beach-Dune Ecosystem and Adjacent Habitats ....................... E-1 Appendix F. U.S. Fish and Wildlife Service Exclosure Protocols for Snowy Plover Nests, July 1999 ............................... F-1 Appendix G. Priorities for Recovery of Threatened and Endangered Species G-1 Appendix H. Conservation Tools and Strategies ..................... H-1 Appendix I. Summary of Potential Funding Sources for Recovery Actions . I-1 Appendix J. Monitoring Guidelines for the Western Snowy Plover, U.S. Pacific Coast Population .................................... J-1 Appendix K. Information and Education Plan for the Western Snowy Plover, U.S. Pacific Coast Population ......................... K-1 Appendix L. Maps of Snowy Plover Sites ........................... L-1 Appendix M. Summary of Public Comments on Draft Recovery Plan and Service Responses .................................. M-1 xv

LIST OF TABLES
Table 1. Status of western snowy plovers at three nesting sites in Washington (1993-2006) ............................... 24 Table 2. Number of adult western snowy plovers on window surveys of the Oregon coast during the breeding season (1978-2006) ..... 25 Table 3. Comparison of breeding-season population estimates of adult western snowy plovers on the Oregon coast (1993-2006) based on three different measures of abundance .................. 26 Table 4. Number of adult snowy plovers during breeding season window surveys on the California coast .......................... 28 Table 5. Breeding season surveys of snowy plover adults at selected sites along the coast of San Luis Obispo, Santa Barbara, and Ventura Counties ............................................ 31 Table 6. Total number of nests at habitat restoration areas on the Oregon Coast 1994-2004 ..................................... 96 Table 7. Total number of fledged young at habitat restoration areas on the Oregon Coast 1994-2004 ............................... 96 Table 8. Threats to the Pacific coast population of the western snowy plover and steps within the recovery plan to reduce or eliminate threats ............................................ 149 xvi

LIST OF FIGURES
Figure 1. Map of known breeding and wintering distribution of Pacific Coast population of western snowy plover (Charadrius alexandrinus nivosus) ............................................. 2 Figure 2. Adult male snowy plover ................................ 5 Figure 3. Oregon Dunes National Recreation Area ................... 8 Figure 4. Western snowy plover clutch ............................ 13 Figure 5. New housing development next to beach at Monterey Bay, California ........................................... 35 Figure 6. Recreationists at Salt Creek Beach, California .............. 58 Figure 7. Equestrians on beach .................................. 68 Figure 8. Erecting western snowy plover exclosure .................. 88 Figure 9. Symbolic fencing on beach at Monterey Bay, California ...... 89 Figure 10. Banding western snowy plover chick .................... 102 Figure 11. High school students removing European beachgrass ........ 104 Figure 12. Chart of recovery planning and implementation efforts ...... 190 xvii
1 I. INTRODUCTION
On March 5, 1993, the Pacific coast population of the western snowy plover (Charadrius alexandrinus nivosus) (western snowy plover) was listed as threatened under provisions of the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.). The Pacific coast population is defined as those individuals that nest within 50 miles of the Pacific Ocean on the mainland coast, peninsulas, offshore islands, bays, estuaries, or rivers of the United States and Baja California, Mexico (U.S. Fish and Wildlife Service 1993a) (Figure 1).

General locations of the western snowy plover’s breeding and wintering locations in the United States are shown in Appendix A. Surveys, status reviews, and literature searches have identified 159 current or historical western snowy plover breeding or wintering locations on the U.S. Pacific coast. These localities include 6 in Washington, 19 in Oregon, and 134 in California (Appendix B). In Baja California, breeding western snowy plovers concentrate at coastal wetland complexes as far south as Bahia Magdalena, Mexico (Palacios et al. 1994). The locations listed in Appendix B are important for the recovery of the United States Pacific coast population of the western snowy plover because they represent important breeding, feeding, and sheltering habitat for the species.

In Washington, the western snowy plover was listed as endangered under Washington Department of Fish and Wildlife Policy #402 in 1981. In 1990 the Washington Fish and Wildlife Commission (Washington Administrative Code 232-12-014) reaffirmed the endangered status. In 1975, the Oregon Fish and Wildlife Commission listed the western snowy plover as threatened. Its threatened status was reaffirmed in 1989 under the Oregon Endangered Species Act and again in 1993 and 1998 by the Oregon Fish and Wildlife Commission as part of its periodic review process. Since 1978, the California Department of Fish and Game has classified both the inland and coastal population of western snowy plover as a “species of special concern.” (Remsen 1978, California Natural Diversity Database 2001).

In August 2002, we received a petition from the Surf Ocean Beach Commission of Lompoc, California to delist the Pacific Coast population of the western snowy 2 Figure 1. Map of known breeding and wintering distribution of the Pacific coast population of the western snowy plover.
3 plover. The City of Morro Bay, California submitted substantially the same petition dated May 30, 2003. On March 22, 2004, we published a notice that the petition presented substantial information to indicate that the delisting may be warranted (U.S. Fish and Wildlife Service 2004a). This notice also announced our initiation of a 5-year status review for the Pacific coast population of western snowy plover.

Under sections 4(b)(3)(B) and 4(c)(2) of the Endangered Species Act, we conducted a 5-year status review and evaluated whether the petitioned action was warranted. On April 21, 2006, we published a 12-month finding that concluded the petitioned action was not warranted (U.S. Fish and Wildlife Service 2006a).

We also proposed a special rule pursuant to section 4(d) of the Endangered Species Act (U.S. Fish and Wildlife Service 2006b), which would exempt counties that have met western snowy plover recovery goals from most prohibitions on take as long as populations remain above recovery goals. The 5-year status review was completed on June 8, 2006.

Section 4 of the Endangered Species Act of 1973, as amended, requires us to develop a recovery plan for the conservation and survival of a species after it is federally listed as threatened or endangered, unless it is determined that such a plan will not promote the conservation of the species. Recovery is the process of reversing the decline of a listed species, eliminating threats, and ensuring the species’ long-term survival. This recovery plan recommends actions necessary to satisfy the biological needs and assure recovery of the Pacific coast population of the western snowy plover. These actions include protection, enhancement, and restoration of all habitats deemed important for recovery; monitoring; research; and public outreach.

This recovery plan will serve as a guidance document for interested parties including Federal, State, and local agencies; private landowners; and the general public. It includes recommendations for western snowy plover management measures for all known breeding and wintering locations (Appendix C). These locations have been divided into six recovery units, as follows: (1) Oregon and Washington; (2) northern California (Del Norte, Humboldt, and Mendocino Counties); (3) San Francisco Bay (locations within Napa, Alameda, Santa Clara, 4 and San Mateo Counties); (4) Monterey Bay (including coastal areas along Monterey, Santa Cruz, San Mateo, San Francisco, Marin, and Sonoma Counties); (5) San Luis Obispo, Santa Barbara, and Ventura Counties; and (6) Los Angeles, Orange, and San Diego Counties. Designation of these locations and recovery units assists in identifying priority areas for conservation planning across the western snowy plover’s breeding and wintering range.

This recovery plan emphasizes management on Federal and State lands, including opportunities to improve or expand upon current efforts. Because of this emphasis on public lands, the cost associated with this emphasis, and potential restrictions of public use on these lands, public support and involvement will be crucial to the recovery of the western snowy plover. Opportunities for public participation in recovery efforts are emphasized in Appendix K (Information and Education Plan).

A. DESCRIPTION AND TAXONOMY
The western snowy plover, a small shorebird in the family Charadriidae, weighs from 34 to 58 grams (1.2 to 2 ounces) and ranges in length from 15 to 17 centimeters (5.9 to 6.6 inches) (Page et al. 1995a). It is pale gray-brown above and white below, with a white hindneck collar and dark lateral breast patches, forehead bar, and eye patches (Figure 2). The bill and legs are blackish. In breeding plumage, males usually have black markings on the head and breast; in females, usually one or more of these markings are dark brown. Early in the breeding season a rufous crown may be evident on breeding males, but it is not typically seen on females. In non-breeding plumage, sexes cannot be distinguished because the breeding markings disappear. Fledged juveniles have buffy edges on their upper parts and can be distinguished from adults until approximately July through October, depending on when in the nesting season they hatched. After this period, molt and feather wear makes fledged juveniles indistinguishable from adults. Individual birds 1 year or older are considered to be breeding adults. The mean annual life span of western snowy plovers is estimated at about 3 years, but at least one individual was at least 15 years old when last seen (Page et al. 1995a).
5 Figure 2. Adult male western snowy plover (photo by Peter Knapp, with permission).

The species was first described in 1758 by Linnaeus (American Ornithologists’ Union 1957). Two subspecies of the snowy plover have been recognized in North America (American Ornithologists’ Union 1957): the western snowy plover (Charadrius alexandrinus nivosus) and the Cuban snowy plover (C. a. tenuirostris). The Pacific coast population of the western snowy plover breeds on the Pacific coast from southern Washington to southern Baja California, Mexico.

Wintering birds may remain at their breeding sites or move north or south to other wintering sites along the Pacific coast. The interior population of the western snowy plover breeds in interior areas of Oregon, California, Nevada, Utah, New Mexico, Colorado, Kansas, Oklahoma, and north-central Texas, as well as coastal areas of extreme southern Texas, and possibly extreme northeastern Mexico (American Ornithologists’ Union 1957). Although previously observed only as a migrant in Arizona, small numbers have bred there in recent years (Monson and Phillips 1981, Davis and Russell 1984). Interior population birds breeding east of the Rockies generally winter along the Gulf coast, while most interior population birds breeding west of the Rockies winter in coastal California and Baja 6 California, often intermingling with birds from the Pacific coast breeding population. The Cuban snowy plover breeds along the Gulf coast from Louisiana to western Florida and south through the Caribbean (American Ornithologists’ Union 1957). More recent works recognize only subspecies C. a. nivosus for North America (Hayman et al. 1986, Binford 1989, Sibley and Monroe 1990).

A large amount of breeding data indicates that the Pacific coast population of the western snowy plover is distinct from western snowy plovers breeding in the interior (U.S. Fish and Wildlife Service 1993a, 2006a). A study conducted between 1977 and 1982 reported that western snowy plovers tend to exhibit breeding site fidelity (Warriner et. al. 1986). Banding and resighting data show that the Pacific Coast breeding populations and the western interior breeding populations experience limited or rare reproductive interchange (G. Page in litt. 2004a). Between 1984 and 1995, the period with the most extensive banding studies and search efforts, 907 plovers color-banded in coastal and interior populations were subsequently resighted (excluding birds banded on the coast during winter and birds resighted in their original region without evidence of nesting). Of these, 894 birds (98.6 percent) were observed during the breeding season using the same breeding range in which they were originally banded.

Twelve birds (1.3 percent) were banded on the coast and later observed in the interior, only one of which was known to nest in the interior. Only one male (0.1 percent) was banded in the interior (without evidence of nesting) and later found nesting on the coast. Moreover, data from a period of less intensive surveys and banding from 1977 to 1983 corroborate this pattern (G. Page in litt. 2004a, U.S.

Fish and Wildlife Service 2006a). During this period, of 400 birds banded in the interior, none were observed on the coast during breeding season, and of 599 birds banded on the coast only one was found nesting in the interior. Finally, 304 retrievals of numbered metal bands reported between 1969 and 2002 show no evidence of movement from interior to coast and only one bird (G. Goldsmith in litt. 2004, U.S. Fish and Wildlife Service 2006a) that moved from coast to interior (the dates being consistent with a bird from the interior population having been banded on the coast during the non-breeding season).

Thus, intensive banding and monitoring studies have documented only two clear instances of interbreeding between coastal and interior populations, and a few 7 cases of inter-population movement without confirmed breeding, among thousands of birds observed. These results illustrate that the amount of interchange between coastal and interior populations is likely to be extremely low, though not zero. Movement of birds from coastal to interior populations has been documented more often than the reverse (see also U.S. Fish and Wildlife Service 2006a).

Genetic studies using mitochondrial DNA and microsatellite DNA markers (Gorman 2000, Funk et al. 2006) have found no significant genetic differentiation between the Pacific coast and interior populations of the western snowy plover.

However, because a small number of dispersing individuals per generation is sufficient to prevent genetic differentiation between two semi-isolated populations (Mills and Allendorf 1996, Funk et al. 2006), this result is consistent with the banding data reported above. Because the small number of dispersing individuals indicated by banding data appear insufficient to substantially affect rates of population growth or decline in either population, the two populations evidently function demographically as largely independent of one another.

Moreover, the infrequency of observed dispersal from coast to interior further indicates that any declines in the coastal population are not likely to be effectively offset by immigration of interior birds to the coast. Consequently there is no evidence that existing unoccupied habitat along the Pacific coast is currently being or in future would be naturally colonized by birds from the interior population (Funk et al. 2006).

B. LIFE HISTORY AND ECOLOGY

1. Breeding
The Pacific coast population of the western snowy plover breeds primarily on coastal beaches from southern Washington to southern Baja California, Mexico (e.g., Figure 3). Sand spits, dune-backed beaches, beaches at creek and river mouths, and salt pans at lagoons and estuaries are the main coastal habitats for nesting (Stenzel et al. 1981, Wilson 1980). This habitat is unstable because of 8 Figure 3. Coastal beach in Oregon Dunes National Recreational Area (photo by Ruth Pratt, with permission)
unconsolidated soils, high winds, storms, wave action, and colonization by plants.

Less common nesting habitats include bluff-backed beaches, dredged material disposal sites, salt pond levees, dry salt ponds, and river bars (Wilson 1980, Page and Stenzel 1981, Powell et al. 1996, Tuttle et al. 1997). a. Population Size and Distribution
Population estimates referenced below are based on window surveys as well as on more intensive studies involving repeated surveys of populations with individually identifiable color-banded birds. Window surveys are a one-time pass of a surveyor, or team of surveyors, through potential western snowy plover nesting habitat during May or June (see survey protocol in Appendix J). The surveyor counts all adult western snowy plovers in the habitat and identifies the adults as male or female, when possible. Because window surveys may not detect all birds, they are not directly comparable to more intensive studies. A correction factor can be estimated by comparing window survey data with concurrent population estimates from detailed studies of color-banded populations; currently 9 the best rangewide estimate of the correction factor is 1.3 (U.S. Fish and Wildlife Service 2006a), but it is preferable to determine corrections on a more specific regional or site basis if possible due to differences in survey efficiency in different habitats (see action 4.3.1).

Western snowy plovers concentrate in suitable habitat, with the number of adults at coastal breeding locations ranging from 1 to 315, depending in part, on the size of the area (Appendix B). The largest number of breeding birds occurs from south San Francisco Bay to southern Baja California (Page and Stenzel 1981, Palacios et al. 1994).

The locations of the following parenthetical references to western snowy plover breeding and wintering locations in Washington, Oregon, and California are shown in Figures A-1 through A-7 of Appendix A, and mapped in greater detail in Appendix L. Information on the numbers of breeding and wintering western snowy plovers at these locations is described in Appendix B.

Four breeding areas currently exist in southern Washington: Damon Point (Washington location 2 [WA-2]) in Grays Harbor; Midway Beach (WA-4); and Leadbetter Point (WA-5) and Graveyard Spit (discovered in 2006) in Willapa Bay. Prior to the 1998 breeding season, fewer than 25 western snowy plovers and 12 nests were found in Washington during regular, standardized surveys.

However, surveys from 1998 through 2006 (Sundstrom 2003, 2005; Brennan and Fernandez 2004a, 2006; Pearson et al. 2006; Washington Department of Fish and Wildlife unpub. data) indicate greater numbers of western snowy plovers are nesting at Leadbetter Point (WA-5) and Midway Beach (WA-4), with a maximum estimated population of 70 western snowy plovers statewide in 2006.

In Oregon, nesting birds have been recorded at 14 sites since 1990 (Castelein et al. 2002, Lauten et al. 2006a, 2006b). Nesting has occurred most frequently at 9 sites, including Sutton (OR-8), Siltcoos (OR-10), Dunes Overlook (OR-10), Tahkenitch (OR-10), Tenmile Spits (OR-12), Coos Bay North Spit (OR-13), Bandon (OR-15), New River (OR-15), and Floras Lake (OR-15). An estimated 177-179 adult western snowy plovers were observed at Oregon sites during the 2006 breeding season. A total of 135 individuals were known to have nested in 10 2006, with 147 nests located. Individual nests have also been found between 1990 and 2002 at several other Oregon sites, including Necanicum (OR-1); Bayocean Spit (OR-3); North Siuslaw (OR-8); Threemile-Umpqua River (OR- 11); and Menasha Spoils, North Bend.

Western snowy plover populations in California have fluctuated between roughly one thousand and two thousand birds over the past 30 years, as detailed in section I.C.1.c below. Eight geographic areas support over three-quarters of the California coastal breeding population: San Francisco Bay (CA-27 to CA-47), Monterey Bay (CA-63 to CA-65), Morro Bay (CA-79 to CA-81), the Callendar- Mussel Rock Dunes area (CA-83), the Point Sal to Point Conception area (CA-84 to CA-88), the Oxnard lowland (CA-96 to CA-99), Santa Rosa Island (CA-93), and San Nicolas Island (CA-100) (Page et al. 1991, G. Page in litt. 2005a).

A survey of breeding western snowy plovers along the Pacific coast of Baja California, Mexico between 1991 to 1992 found 1,344 adults, mostly at four coastal wetland complexes: Bahia San Quintin, Lagunas Ojo de Liebre and Guerrero Negro, Laguna San Ignacio, and Bahia Magdalena (Palacios et al. 1994).
b. Arrival and Courtship
Nesting western snowy plovers at coastal locations consist of both year-round residents and migrants (Warriner et al. 1986). Migrants begin arriving at breeding areas in southern Washington in early March (Widrig 1980) and in central California as early as January, although the main arrival is from early March to late April (Page et al. 1995a). Since some individuals nest at multiple locations during the same year, birds may continue arriving through June (Stenzel et al. 1994).

Mated birds from the previous breeding season frequently reunite. Pair bonds are associated with territorial defense by males and nest scraping behavior, but early in the season birds begin to associate with one another in pairs within and apart from roosting flocks before nest scraping activity is observed, suggesting that pair bonds can be established prior to overt displays (Warriner et al. 1986). A scrape 11 is a depression in the sand or substrate that a male constructs by leaning forward on his breast and scratching his feet while rotating his body axis (Page et al. 1995a). Copulations are associated with scraping behavior (Warriner et al. 1986).

Females choose which scrape becomes the nest site by laying eggs in one of them.

In California, pre-nesting bonds and courtship activities are observed as early as mid-February. Similar activities begin by March in Oregon. During courtship, males defend territories and usually make multiple scrapes. c. Duration of Breeding Season
Along the west coast of the United States, the nesting season of the western snowy plover extends from early March through late September. Generally, the breeding season may be 2 to 4 weeks earlier in southern California than in Oregon and Washington. Fledging (reaching flying age) of late-season broods may extend into the third week of September throughout the breeding range.

The earliest nests on the California coast occur during the first week of March in some years and by the third week of March in most years (Page et al. 1995a).

Peak initiation of nesting is from mid-April to mid-June (Warriner et al. 1986; Powell et al. 1997). Hatching lasts from early April through mid-August, with chicks reaching fledging age approximately 1 month after hatching (Powell et al. 1997). On the Oregon coast nesting may begin as early as mid-March, but most nests are initiated from mid-April through mid-July (Wilson-Jacobs and Meslow 1984); peak nest initiation occurs from mid-May to early July (Stern et al. 1990).

In Oregon, hatching occurs from mid-April through mid-August, with chicks reaching fledging age as early as mid- to late May. Peak hatching occurs from May through July, and most fledging occurs from June through August. On the Washington coast, most adults arrive during late April, with maximum numbers present from mid-May to late June. Fledging occurs from late June through August (Washington Department of Fish and Wildlife 1995). d. Nests and Nest Sites
Nests typically occur in flat, open areas with sandy or saline substrates; vegetation and driftwood are usually sparse or absent (Widrig 1980, Wilson 1980, 12 Stenzel et al. 1981). Western snowy plovers also regularly nest on the gravel bars along the Eel River in northern California. In southern California, western snowy plovers nest in areas with 6 to 18 percent vegetative cover and 1 to 14 percent inorganic cover; vegetation height is usually less than six centimeters (2.3 inches) (Powell et al. 1995, 1996). Nests consist of a shallow scrape or depression, sometimes lined with beach debris (e.g., small pebbles, shell fragments, plant debris, and mud chips); nest lining increases as incubation progresses. Driftwood, kelp, and dune plants provide cover for chicks that crouch near objects to hide from predators. Invertebrates are often found near debris, so driftwood and kelp are also important for harboring western snowy plover food sources (Page et al. 1995a). Page and Stenzel (1981) found that nests were usually within 100 meters (328 feet) of water, but could be several hundred meters away when there was no vegetative barrier between the nest and water. They believed the absence of such a barrier is probably important for newly-hatched chicks to have access to the shore. Powell et al. (1995, 1996) also reported that nests from southern California were usually located within 100 meters (328 feet) of water, which could be either ocean, lagoon, or river mouth. Although the majority of western snowy plovers are site-faithful, returning to the same breeding area in subsequent breeding seasons, some also disperse within and between years (Warriner et al. 1986, Stenzel et al. 1994). Western snowy plovers occasionally nest in exactly the same location as the previous year (Warriner et al. 1986). e. Egg Laying, Clutch Size, and Incubation
Initiation (eggs and laying) occurs from mid-February/early March through the third week of July (Wilson 1980, Warriner et al. 1986). The approximate periods required for nesting events are: scrape construction (in conjunction with courtship and mating), 3 days to more than a month; egg laying, usually 4 to 5 days; and incubation, 26 to 31 days (mean 27 days) (Warriner et al. 1986). The usual clutch size (e.g., number of eggs in one nest) is three (Figure 4) with a range from two to six. (Warriner et al. 1986, Page et al. 1995a). Both sexes incubate the eggs, with the female tending to incubate during the day and the male at night (Warriner et al. 1986). Adult western snowy plovers frequently will attempt to lure people and predators from hatching eggs with alarm calls and distraction displays. Occasionally, adults behave similarly during the egg-laying period or 13 Figure 4. Western snowy plover clutch (photo by Bruce Casler, with permission).
incubation of completed clutches. More typical, however, is for the incubating adult to run away from the eggs without being seen. Incomplete clutches are those in which all eggs have not been laid. Partly-incubated clutches are those clutches having some degree (in days) of incubation.

Western snowy plovers will re-nest after loss of their eggs (Wilson 1980, Warriner et al. 1986). Re-nesting occurs 2 to 14 days after failure of a clutch, and up to five re-nesting attempts have been observed for a pair (Warriner et al. 1986).

Double brooding with polyandry (meaning the female successfully hatches more than one brood [i.e. sibling chicks of a hatched nest] in a nesting season with different mates) is common in coastal California (Warriner et al. 1986) and Oregon (Wilson-Jacobs and Meslow 1984). On the California coast, the breeding season is long enough for some females to triple brood and for some males to double brood (Page et al. 1995a). Triple brooding in a male has, on rare occasion, been recorded; a male triple brooded at Moss Landing salt ponds in 2001 (D. George in litt. 2001). After losing a clutch or brood or successfully 14 hatching a nest, western snowy plovers may re-nest at the same site or move up to several hundred kilometers to nest at other sites (Stenzel et al. 1994, Powell et al. 1997 ).
f. Clutch Hatching Success
Widely varying clutch hatching success (percent of clutches hatching at least one egg) is reported in the literature. Clutch hatching success ranging from 0 to 90 percent has been recorded for coastal western snowy plovers (Widrig 1980, Wilson 1980, Saul 1982, Wilson-Jacobs and Dorsey 1985, Warriner et al. 1986, Wickham unpubl. data in Jacobs 1986). Low clutch hatching success has been attributed to a variety of factors, including predation, human disturbance, high tides, and inclement weather. Heavy recreational beach use coincides with the peak hatching period for western snowy plover eggs (Powell 2001), adding additional pressures to western snowy plover adults and chicks that are more exposed to human disturbance. Observed clutch hatching success ranged from

12.5 to 86.8 percent and averaged 50.6 percent in eight studies of coastal breeding western snowy plovers (Page et al. 1995a). In San Diego County, estimated nesting success ranged from 43 to 68 percent between 1994 and 1998, averaging 54 percent (Powell et al. 2002); nesting western snowy plovers in San Diego County likely benefitted from predator management efforts for snowy plovers and California least terns (Sternula antillarum browni) (A. Powell, U.S. Geological Survey, pers. comm. 1998). In Monterey Bay, hatching rate was significantly increased from 43 percent (during 1984-1990) to 68 percent (during 1991-1999) by intensive control of mammalian predators and use of nest exclosures (Neuman et al. 2004).
g. Brood-rearing
The first chick hatched remains in or near the nest until other eggs (or at least the second egg) hatch. The adult western snowy plover, while incubating the eggs, also broods the first chick. The non-incubating adult also may brood the first- born chick a short distance from the nest. If the third egg of a clutch is 24 to 48 hours behind the others in hatching, it may be deserted. Western snowy plover chicks are precocial, leaving the nest within hours after hatching to search for 15 food. They are not able to fly (fledge) for approximately 1 month after hatching; fledging requires 28 to 33 days (Warriner et al. 1986). Broods rarely remain in the nesting area until fledging (Warriner et al. 1986, Stern et al. 1990). Western snowy plover broods may travel along the beach as far as 6.4 kilometers (4 miles) from their natal area (Casler et al. 1993).

Adult western snowy plovers do not feed their chicks, but lead them to suitable feeding areas. Adults use distraction displays to lure predators and people away from chicks. With vocalizations, adult western snowy plovers signal the chicks to crouch as another way to protect them (Page et al. 1995a). They also may lead chicks, especially larger ones, away from predators. Warriner et al. (1986) reported that most chick mortality occurs within 6 days after hatching.

Females generally desert mates and broods by the sixth day after hatching and thereafter the chicks are typically accompanied by only the male. While males rear broods, females obtain new mates and initiate new nests (Page et al. 1995a).

Females typically help rear the last brood of the season. h. Fledging success
The fledging success of western snowy plovers (percentage of hatched young that reach flying age) varies greatly by location and year. Even western snowy plovers nesting on neighboring beach segments may exhibit quite different success in the same year. For example, the percentage of chicks fledged on different beach segments of Monterey Bay in 1997 varied from 11 to 59 percent (average 24 percent) (Page et al. 1997). During the prior 13 years, fledging success on Monterey Bay beaches averaged 39 percent (Page et al. 1997). From the former Moss Landing salt ponds (now known as the Moss Landing Wildlife Area) in Monterey Bay (CA-64), fledging success ranged from 13.2 percent to

57.1 percent from 1988 to 1997. In San Diego County, fledging success ranged from 32.6 to 51.4 percent (Powell et al. 1997). In Oregon, annual fledging success for 1992 to 2006, for all coastal sites combined, ranged from 26 to 55 percent (Lauten et al. 2006a, 2006b). As in California, there is considerable variation among sites within years. For example, in 2005, the fledging success ranged from 24 percent at New River (OR-15) to 70 percent at Coos Bay South 16 Beach (OR-13). There also is variation at individual sites among years. At the Coos Bay North Spit (OR-13), one of the larger nesting areas in coastal Oregon, annual fledging success for 1992 to 2006 ranged from 38 to 74 percent. i. Productivity
The productivity information most useful for this recovery plan is reproductive success (the annual number of young fledged per adult male). For the population viability analysis (Appendix D), males were used in the model because their population parameters can be estimated with greater certainty than for females. In addition, it is reasonable to consider that the availability of males is limiting reproductive success because they are responsible for post-hatching parental care, and females can lay clutches for more than one male (Warriner et al. 1986).

Chicks are considered fledged at 28 to 33 days after hatching. Estimates of the number of young fledged per adult male are available for Oregon; northern California from Mendocino to Del Norte Counties; Monterey Bay, California; and San Diego County, California. Along the Oregon coast, the average number of young annually fledged per male during the period between 1992 and the initiation of predator management (2002 to 2004 depending on site) was estimated as 0.87 (Lauten et al. 2006b); this fledging success significantly increased to 1.44 since implementation of predator management. Male fledging success in Oregon has annually ranged between 0.70 and 1.64 (Lauten et al. 2006a). In northern California, fledging success ranged from 0.8 to 1.7 fledglings per male between 2001-2005, with birds nesting on river gravel bars consistently achieving greater success than those nesting on beaches (Colwell et al. 2005). At Monterey Bay, California, from 1984 to 1990, when little effort was made to protect chicks from predators and people, males averaged 0.86 fledglings annually. When intensive efforts were undertaken to control mammalian predators from 1993 to 1999, the number of young fledged per adult male initially increased above 1.1, then declined sharply as avian predation on chicks became increasingly significant (Neuman et al. 2004). After live trapping and removal of avian predators was initiated, fledging success again increased in target areas (G.

Page in litt. 2004b). Over 16 years of study at Monterey Bay, the annual number of young fledged ranged from 0.32 to 1.23 per male (Neuman et al. 2004). In San 17 Diego County from 1994 to 1998, an average of 0.15 to 0.44 young were fledged per male (Powell et al. 2002). Fledging success in Washington cannot be accurately estimated due to lack of banded chicks and adults and variable monitoring effort prior to 2006 (S. Pearson in litt. 2006); however it was roughly estimated at between 0.76 and 1.45 young fledged per male in 2006, excluding Leadbetter Point which was insufficiently surveyed but may have had poorer fledging success (Pearson et al. 2006).
j. Survival
Annual survival rates for adult and juvenile western snowy plovers have been calculated from studies of color banded birds from the coast of Oregon (M. Stern unpubl. data), the shoreline of Monterey Bay, California (Point Reyes Bird Observatory unpublished data), and the coast of San Diego County, California (A.

Powell and J. Terp unpublished data) using the program SURGE (Lebreton et al. 1992, Cooch et al. 1996). Annual juvenile survival rates for fledged young average 48.5 percent (1992-2002) from the Oregon coast, 45 percent from Monterey Bay, and 45 percent from the San Diego coast. Annual survival rates for adult females and males, respectively, averaged 75 and 75 percent from the Oregon coast, 69 and 75 percent from Monterey Bay, and 72 and 71 percent from the San Diego coast. Differences between males and females were statistically significant only for the Monterey Bay area. Appendix D explains how these survival rates were incorporated into the population viability analysis.

2. Feeding Habitat and Habits
Western snowy plovers are primarily visual foragers, using the run-stop-peck method of feeding typical of Charadrius species. They forage on invertebrates in the wet sand and amongst surf-cast kelp within the intertidal zone, in dry sand areas above the high tide, on salt pans, on spoil sites, and along the edges of salt marshes, salt ponds, and lagoons. They sometimes probe for prey in the sand and pick insects from low-growing plants. At the Bolsa Chica wetlands in California, western snowy plovers have been observed pecking small, flying insects from mid-air and shaking one foot in very shallow water to agitate potential prey (Fancher et al. 1998). Western snowy plover food consists of immature and adult 18 forms of aquatic and terrestrial invertebrates. Little quantitative information is available on food habits. In San Diego, California, invertebrates found in western snowy plover feces during the breeding season included rove beetles (Staphylinidae), long-legged flies (Dolichopodidae), shore flies (Ephydridae), water bugs (Saldidae), hymenopterans (Braconidae), and unidentified insect larvae (Tucker and Powell 1999). During the breeding season, Jacobs (1986) observed adult western snowy plovers feeding on sand hoppers (Orchestoidea) and small fish on the Oregon coast. Other food items reported for coastal western snowy plovers include Pacific mole crabs (Emerita analoga), striped shore crabs (Pachygrapsus crassipes), polychaetes (Neridae, Lumbrineris zonata, Polydora socialis, Scoloplos acmaceps), amphipods (Corophium ssp., Ampithoe spp., Allorchestes angustus), tanadacians (Leptochelia dubia), shore flies (Ephydridae), beetles (Carabidae, Buprestidae, Tenebrionidae), clams (Transenella sp.), and ostracods (Page et al. 1995a). In salt evaporation ponds in San Francisco Bay, California, the following prey have been recorded: brine flies (Ephydra cinerea), beetles (Tanarthrus occidentalis, Bembidion sp.), moths (Perizoma custodiata), and lepidopteran caterpillars (Feeney and Maffei 1991). Opportunities for foraging are directly dependent on salinity levels. Specifically, salt ponds of medium salinity seem to provide the best quality foraging habitat (M. Kolar, San Francisco Bay National Wildlife Refuge, pers. comm. 2004).

3. Migration
While some western snowy plovers remain in their coastal breeding areas year- round, others migrate south or north for winter (Warriner et al. 1986, Page et al. 1995a, Powell et al. 1997). In Monterey Bay, California, 41 percent of nesting males and 24 percent of the females were consistent year-round residents (Warriner et al. 1986). At Marine Corps Base Camp Pendleton in San Diego County, California, about 30 percent of nesting birds stayed during winter (Powell et al. 1995, 1996, 1997). The migrants vacate California coastal nesting areas primarily from late June to late October (Page et al. 1995a). There is evidence of a late-summer (August/September) influx of western snowy plovers into Washington; it is suspected that these wandering birds are migrants (S.

Richardson, Washington Department of Fish and Wildlife, pers. comm. 1998). 19 Most western snowy plovers that nest inland migrate to the coast for the winter (Page et al. 1986, 1995b). Thus, the flocks of non-breeding birds that begin forming along the U.S. Pacific coast in early July are a mixture of adult and hatching-year birds from both coastal and interior nesting areas. During migration and winter, these flocks range in size from a few individuals to up to 300 birds (Appendix B).

4. Wintering
a. Distribution and Abundance
In western North America, the western snowy plover winters (here defined as late October to mid-February) mainly in coastal areas from southern Washington to Central America (Page et al. 1995a). Both coastal and interior populations use coastal locations in winter. Small numbers of western snowy plovers occur at two locations on the Washington coast: Midway Beach (WA-4) (S. Richardson, pers. comm. 1998, J. Grettenberger, U.S. Fish and Wildlife Service, pers. comm. 2004), and Leadbetter Point (WA-5), Willapa Bay (Washington Department of Fish and Wildlife 1995), both in Pacific County. Increasing numbers of wintering western snowy plovers are being documented along the Washington coast, with 32 counted in 2005 (L. Kelly in litt. 2005). As many as 97 western snowy plovers were observed wintering on the Oregon coast in 2005 (L. Kelly in litt. 2005).

During the survey period between 1990 and 2005, at least 9 Oregon locations (Appendix B) have been used by wintering plovers. Probably as many as 2,500 plovers overwinter along the mainland California coast, and hundreds more at San Francisco Bay and in the Channel Islands (Appendix B, Page et al. 1986). The majority of wintering western snowy plovers on the California coast are found from Bodega Bay, Sonoma County, southward (Page et al. 1986). Appendix B gives the range of years over which each state’s data was collected as well as the minimum and maximum number of western snowy plovers inventoried.

Nesting western snowy plovers from the Oregon coast have wintered as far south as Monterey Bay, California; those from Monterey Bay in central California have wintered north to Bandon, Oregon, and south to Laguna Ojo de Liebre, Baja California, Mexico (Page et al. 1995a); and those from San Diego in southern 20 California have wintered north to Vandenberg Air Force Base in Santa Barbara County and south to Laguna Ojo de Liebre, Baja California, Mexico (Powell et al. 1995, 1996, 1997).

In winter, western snowy plovers are found on many of the beaches used for nesting, as well as some beaches where they do not nest (Appendix B). They also occur in man-made salt ponds and on estuarine sand and mud flats. In California, the majority of wintering western snowy plovers concentrate on sand spits and dune-backed beaches. Some also occur on urban and bluff-backed beaches, which are rarely used for nesting (Page et al. 1986). Pocket beaches at the mouths of creeks and rivers on otherwise rocky shorelines are used by wintering western snowy plovers south, but not north, of San Mateo County, California. b. Site Fidelity
Western snowy plovers that breed on the coast and inland are very site faithful in winter (Point Reyes Bird Observatory unpublished data). For example, after 166 adults and 204 chicks were banded at Lake Abert, Oregon during summer, many were subsequently found along the California and Baja California, Mexico coasts.

Of those for which a wintering location was identified, 67 percent of the adult males, 73 percent of the adult females, and 60 percent of the birds banded as chicks (immatures) were found at the same winter location in at least 2 consecutive years; and 33 percent of the males, 32 percent of the females, and 35 percent of the immatures for at least 3 years (Page et al. 1995b). c. Behavior
Western snowy plovers are typically gregarious in winter. Although some individuals defend territories on beaches, most usually roost in loose flocks; frequently western snowy plovers also are observed foraging in loose flocks (Page et al. 1995a). Roosting western snowy plovers usually sit in small depressions in the sand, or in the lee of kelp, other debris, or small dunes (Page et al. 1995a). Sitting behind debris or in depressions provides some shelter from the wind and probably makes the birds more difficult for predators to detect. When roosting western snowy plovers are disturbed, they frequently run a few meters to 21 a new spot where they sometimes displace other individuals. Alternatively, the whole flock may fly to a new location.

C. POPULATION STATUS AND TRENDS

1. Historical Trends
Historical records indicate that nesting western snowy plovers were once more widely distributed and abundant in coastal Washington, Oregon, and California. a. Washington Coast
In Washington, western snowy plovers formerly nested at five coastal locations (Washington Department of Fish and Wildlife 1995). Three of these sites have had active nesting in recent years, as summarized in Table 1. One new site was also recently discovered in 2006. Populations appear to have increased overall since the early 1990s, although consistent, intensive surveys have been conducted only since the mid-1990s. Quantitative comparisons prior to that are not possible because of the inconsistency in surveys. Estimated numbers of breeding adults (Table 1) substantially exceed window survey data (M. Jensen in litt. 2006), partially because of adverse weather during window survey periods in recent years.
i. Grays Harbor County
Copalis Spit (WA-1) held 6 to 12 western snowy plover pairs in the late 1950s or early 1960s (Washington Department of Fish and Wildlife 1995). No other information on breeding at Copalis Spit is available. Suitable habitat was judged capable of supporting four pairs in 1984 (Washington Department of Fish and Wildlife 1995). Periodic surveys since 1983 have revealed just a single western snowy plover (Washington Department of Fish and Wildlife unpubl. data). Two post season juvenile western snowy plovers were observed at Copalis Spit in 2001 (Sundstrom 2002a). There is no longer vehicle access to the site since the road washed out several years ago, which has reduced the potential for disturbance from recreational activities. Erosion caused by the northward shift of Connor 22 Creek has reduced the amount of habitat, but some suitable habitat remains at the end of the spit and the area has potential as a nesting site with habitat restoration and public education (U.S. Fish and Wildlife Service 2005, M. Jensen in litt. 2006).

Damon Point and Oyhut Wildlife Area (WA-2) lack western snowy plover records prior to 1971, but this is likely due to limited visitation rather than western snowy plover absence. Between 1971 and 1983, birders reported up to six western snowy plovers during infrequent visits-to Damon Point (Washington Department of Fish and Wildlife 1995). Western snowy plover research in 1985 and 1986 revealed up to 20 western snowy plovers and 8 nests at Damon Point (Anthony 1987). Although most of the locality is suitable habitat, increasing levels of public use have reduced the secure nesting areas to a small portion of the site that is difficult to access, and the breeding population has declined over the last two decades (M. Jensen in litt. 2006). From 1993 to 2006 the number of adults at Damon Point has ranged from 2 to 10 (Table 1). Only one nest was found in 2006 (Pearson et al. 2006).

Westport Spit (WA-3) held low numbers of western snowy plovers from before 1915 until at least 1968, and scientific collecting was concentrated there through 1934 (Washington Department of Fish and Wildlife 1995). A single nest, poorly documented, was reported in 1983 (Washington Department of Fish and Wildlife unpublished data). No other quantitative information on abundance or nesting is available for this site. Erosion of the site has rendered the beach too narrow to support successful nesting, and there is little opportunity for habitat restoration through beachgrass removal due to private ownership of upland dune habitat (M.

Jensen in litt. 2006). Recreational use is also substantial. This location is no longer being surveyed due to lack of suitable habitat.
ii. Pacific County
Midway Beach (WA-4) and Cape Shoalwater once contained several hundred acres of suitable western snowy plover habitat, but the area lacks historical records of these birds except for specimens collected in 1914 and 1960 and labeled “Tokeland” (Washington Department of Fish and Wildlife 1995). In 23 recent years, Midway Beach has been accreting sand and creating high quality habitat. Recent nesting was first documented in 1998 (Richardson et al. 2000).

Numbers of breeding adults have increased since 1998, and during 2003-2006 the numbers of adults during the breeding season have ranged from 23-33, with a peak number of 30 nests (M. Jensen in litt. 2006; Pearson et al. 2006).

Approximately one third of the habitat is on State Park land with controlled access; on the privately owned land recreational disturbance is fairly high and contributes to high rates of nest failure.

In 2006, western snowy plovers were discovered nesting on Graveyard Spit in northern Willapa Bay, which is primarily on the Shoalwater Indian Reservation and State lands (M. Jensen in litt. 2006; Pearson et al. 2006). Three pairs of plovers used the spit in 2006 and produced three fledglings.

Leadbetter Point (WA-5) was rarely visited by western snowy plover observers prior to 1964. In the 1960s and 1970s, birders reported up to 35 western snowy plovers, with nesting confirmed in 1967 by the sighting of two chicks (Washington Department of Fish and Wildlife 1995). Western snowy plover numbers were estimated at up to 24 individuals and between 7 and 11 nests during surveys done between 1978 to 1997 (Widrig 1980, 1981; Willapa National Wildlife Refuge unpublished data; Williamson 1995, 1996, 1997). Numbers increased slightly from 1998-2006, with numbers ranging from 24 to 45 adults present (Table 1). The distribution of nesting by western snowy plovers has changed, however, with recent habitat loss from erosion on the tip of Leadbetter Point and shifting of nesting southwards. Since 2002 the refuge has cleared 25 hectares (63 acres) of non-native beachgrass and the habitat restoration site has been consistently used by nesting plovers. Western snowy plovers are also nesting in Leadbetter State Park and State-owned lands south of the Park. Use of predator exclosures at the refuge since 2004 has greatly improved hatching success in the habitat restoration area and outer beach. Gunpowder Sands Island became intertidal in 2001 and no longer is suitable for nesting western snowy plovers (K. Brennan in litt. 2006).
24 Table 1. Status of western snowy plovers at four nesting sites in Washington (Sundstrom-Bagley et. al. 2000; Jaques 2001; Sundstrom 2001, 2002a, 2002b, 2003, 2004, 2005; Brennan and Jaques 2002; Brennan 2003; Brennan and Fernandez 2004a, 2004b, 2006; Pearson et al. 2006).

Year Estimated Number of Adul ts Present
Leadbetter
Point
Midway
Beach
Damon
Point
Graveyard
Spit
Total
1993 16 - 7 - 23
1994 13 - 6 - 19
1995 25 0 9 - 34
1996 19 0 4 - 23
1997 21 0 3 - 24
1998 45 6 5 - 56
1999 26 12 5 - 43
2000 25 21 4 - 50
2001 27 14 4 - 45
2002 32 23 4 - 59
2003 30 33 5 - 68
2004 24 19 10 - 53
2005 38 25 5 - 68
2006 39 23 2 6 70
b. Oregon Coast
In Oregon, western snowy plovers historically nested at over 20 sites on the coast.

At present only seven core nesting sites are consistently used, with a few additional areas occupied during some years (Lauten et al. 2006a, 2006b).

Annual window surveys of western snowy plovers in Oregon (Table 2), including both adults and young of the year, began in 1978, with counts ranging from a high of 139 at 13 sites (1981) to a low of 30 observed at 9 sites (1992). Populations reached a low from 1991 to 1993 with a mean of 33 individuals recorded annually. From 1994 to 2006 western snowy plover numbers have generally 25 Table 2. Number of adult western snowy plovers observed on window surveys of the Oregon coast during the breeding season (1978-2006). Window surveys record the number of birds seen during 1-day censuses in May to June (Lauten et al. 2006a, 2006b).

Year Number Year Number
1978 93 1993 45
1979 100 1994 51
1980 80 1995 64
1981 139 1996 85
1982 78 1997 73
1983 52 1998 57
1984 46 1999 49
1985 48 2000 no surveys conducted
1986 73 2001 71
1987 61 2002 71
1988 53 2003 63
1989 58 2004 82
1990 59 2005 100
1991 35 2006 91
1992 30
increased, with an average of 71 plovers observed. The increase in the numbers of plovers observed in recent years is believed to be related to intensive management that began at the time of Federal listing.

Since 1993, the population on the Oregon coast has been intensively monitored, with many of the adults and chicks being uniquely color-banded. The presence of marked birds has allowed for the development of two other means of estimating the population (Table 3, Lauten et al. 2006b). The number of western snowy plovers, as indicated by the three indices in Table 3, has increased between 1993 and 1997, declined in 1998/1999, then increased again through 2006. The trends 26 Table 3. Comparison of population estimates of adult western snowy plovers on the Oregon coast during the breeding season (1993 to 2005) based on three different measures of abundance (Lauten et al. 2006a, 2006b).

Year Estimates

A B C
1993 45 55 to 61 72
1994 51 67 83
1995 64 94 120
1996 85 110 to 113 134 to 137
1997 73 106 to 110 141
1998 57 75 97
1999 45 77 95 to 96
2000 no survey 89 109
2001 71 79 to 80 111 to 113
2002 71 80 99 to 102
2003 63 93 102 to 107
2004 82 120 136 to 142
2005 100 104 153 to 158
2006 91 135 177 to 179
A = Window census.

B = Estimated number of breeding adults. This number is lower than those in column C because it is an estimate of t he number of individual birds thought to be breeding birds.

C = Total number of indi vidual adults present duri ng breeding season (i ncludes depredated adults).
for all three indices remained relatively consistent throughout that measurement period.

Management measures (Lauten et al. 2006a, 2006b) have included the use of exclosures to reduce predation, predator control measures, restoration of breeding habitat by removing European beachgrass (Ammophila arenaria), increased presence of law enforcement personnel, additional and improved signs, additional symbolic fencing (consisting of one or two strands of light-weight string or cable 27 tied between posts to delineate areas where pedestrians and vehicles should not enter), and increased efforts on public information and education. c. California Coast
i. Coastwide Perspecti ve
In California, there also has been a significant decline in breeding locations, especially in southern California. By the late 1970s, nesting western snowy plovers were absent from 33 of 53 locations with breeding records prior to 1970 (Page and Stenzel 1981). The first quantitative data on the abundance of western snowy plovers along the California coast came from window surveys conducted during the 1977 to 1980 breeding seasons by Point Reyes Bird Observatory (Page and Stenzel 1981). An estimated 1,593 adult western snowy plovers were seen on these pioneer surveys (Table 4). The surveys suggested that the western snowy plover had disappeared from significant parts of its coastal California breeding range by 1980. It no longer bred along the beach at Mission Bay or at Buena Vista Lagoon in San Diego County. In Orange County, the only remaining breeding location was the Bolsa Chica wetlands; historically, the western snowy plover was known to breed along the beach from Upper Newport Bay to Anaheim Bay. It was absent from Los Angeles County where it formerly nested along the shores of Santa Monica Bay. In Ventura County, it had ceased breeding on Ventura Beach (San Buenaventura Beach), and in Santa Barbara County on Carpinteria, Santa Barbara (East Beach), and Goleta Beaches. Nesting no longer occurred along the northernmost portion of Monterey Bay in Santa Cruz County or on Doran Beach at Bodega Harbor in Sonoma County.

Subsequent coast-wide surveys by Point Reyes Bird Observatory in 1989 and 1991 indicated a further decline in numbers of breeding adult western snowy plovers during the decade after the 1977 to 1980 survey. Along the mainland coast, including the shores of the Channel Islands, western snowy plover populations had declined by about 5 percent, and in San Francisco Bay by about 44 percent (Table 4).
28 Table 4. Number of adult western snowy plovers observed during breeding season window surveys of the California coast.

Location 1977/80 1989 1991 1995 2000 2002 2003 2004 2005 2006 Del Norte County 11 8 3 0 0 0 0 0 0 0
Humboldt County 54 32 30 19 39 49 38 37 32 49
Mendocino County 15 2 0 - 1 0 1 3 9 3
Sonoma County 0 10 9 3 0 0 0 0 5 0
Marin County 40 24 25 8 21 25 17 26 22 16
San Mateo County
(incl. SF beaches)
4 8 1 - 4 3 4 17 3 7
Northern Santa Cruz
County
25 19 22 26 19 9 2 2 3 4
Monterey Bay 146 146 119 125 120 270 279 331 297 317
Point Sur 3 4 - - 8 5 6 5 7 13
Northern San Luis
Obispo County
9 - 1 3 0 3 12 15
Morro Bay Area 80 126 87 85 113 150 172 268 259 167
Pismo Beach/Santa
Maria River
45 123 246 124 81 170 137 167 200 211
Vandenberg AFB 119 115 242 213 106 179 256 420 259 245
Jalama Beach 0 1 1 0 0 0 0 0 0 0
Hollister Ranch 8 - - - - - - -
Coal Oil Point
(Devereaux) vicinity
- - - 8 26 30 30 39
Oxnard Lowland 136 175 105 69 107 164 80 119 110 125
Channel Islands (288)1 217 200 196 89 79 90 82 99 115
Orange County 19 21 5 9 27 38 31 31 66 62
Northern San Diego
County
160 72 48 49 63 80 145 159 107 141
Mission Beach - - - - - 1 0 -
San Diego Bay 60 36 31 33 73 61 76 76 30 81
Tijuana Estuary 37 21 4 10 8 16 12 14 6 14
Subtotal 1,242 1,160 1,195 969 880 1,309 1,372 1,791 1,556 1,624 S San Francisco Bay 351 216 176 - 96 78 72 113 124 99
Total 1,593 1,376 1,371 - 976 1,387 1,444 1,904 1,680 1,723 1 260 adults duri ng the survey; 28 addi tional adult s extrapolat ed for unsurveyed port ions of Santa Rosa Is land. 29 The more recent coast-wide surveys, during the summers of 1995, 2000, and 2002- 2006, were accomplished through the collaboration of researchers studying western snowy plovers along the California coast. Between the 1977 to 1980 surveys and the 1995 survey, western snowy plovers apparently ceased nesting at Los Penasquitos, and Agua Hedionda Lagoons in northern San Diego County (A.

Powell, pers. comm. 1998). Nesting has been absent or sporadic at San Elijo Lagoon; Año Nuevo State Beach and Pescadero State Beach in San Mateo County; Bolinas Lagoon in Marin County; the south and north spits of Humboldt Bay and Big Lagoon in Humboldt County; and the Lake Talawa region of Del Norte County (Point Reyes Bird Observatory, unpublished data).

By 2000 populations had declined further to 71 percent of the 1977-1980 levels along the California coast and 27 percent of the 1977-1980 levels in San Francisco Bay. However, since then populations have grown substantially, roughly doubling along the coast while fluctuating irregularly in San Francisco Bay (Table 4).

Recent population increases along the coast have been associated with implementation of management actions for the benefit of western snowy plovers and California least terns, including predator management and protection and restoration of habitat.
ii. Regional Perspective
Del Norte, Humboldt, and Mendocino Counties - Numbers of western snowy plover breeding adults declined and then somewhat rebounded in this northern California region since the initial Point Reyes Bird Observatory survey in 1977. In this region where there were 80 adults counted in 1977, a low of 19 were found in 1995 and 52 in 2006. In 1996, breeding was documented on the gravel bars of the Eel River, Humboldt County, and this area has continued to be a successful nesting site for western snowy plover breeding (Colwell et al. 2002, 2005). Even with the nest success at the gravel bars there is still a reduction in western snowy plovers from 1977; Del Norte County has no breeding birds, and Mendocino County has very few.

San Francisco Bay - As indicated in Table 4, western snowy plover numbers in San Francisco Bay declined markedly between the initial survey in 1978 and 30 follow-up surveys. Western snowy plover numbers steadily declined over 26 years, reaching a low of 72 in 2003, followed by a moderate but irregular increase (124 in 2005 surveys; 99 in 2006).

Recent surveys in South San Francisco Bay (Strong and Dakin 2004, Strong et al. 2004, Tucci et al. 2006) indicate that the largest breeding populations are concentrated at Eden Landing Ecological Reserve/Baumberg North (CA-33), managed by California Department of Fish and Game. Other population centers occur at Oliver Salt Ponds (CA-31), managed by Hayward Area Recreation District and East Bay Regional Parks District; and at Dumbarton (CA-36), Warm Springs (CA-39), Alviso (CA-41), and Ravenswood (CA-44), managed by Don Edwards San Francisco Bay National Wildlife Refuge. Foraging and nesting activities are concentrated in specific salt ponds within these areas. Small numbers of western snowy plovers have been observed at Ponds 7 and 7A in Napa County (CA-25 and vicinity), the only currently known nesting site in the North Bay.

Sonoma, Marin, San Francisco, San Mateo, Santa Cruz, and Monterey Counties - Along the segment of coastline from Sonoma County to Monterey Bay, numbers of western snowy plover adults during window surveys declined from 215 in 1977 to 162 in 1995, and subsequently increased to a maximum of 376 in 2004.

The numbers of adults breeding on the beaches and salt ponds of Monterey Bay, and the beaches of northern Santa Cruz County, has increased dramatically since management actions have been undertaken to increase nesting success (Neuman et al. 2004; G. Page in litt. 2004b)
San Luis Obispo, Santa Barbara, and Ventura Counties, including Channel Islands - There is no clear evidence of an overall decline in the number of breeding western snowy plovers for this region from 1978/1980 to the present.

Numbers of adults fluctuated between a high of 1089 and a low of 497 between 1978 and 2006. While numbers for the region may not have changed overall, there have been definite changes at specific locations (Table 5). Most notable are the decline and loss of the population on San Miguel Island from 1978 /1980 to 2000, the decline at Santa Rosa Island from 1991 to 2006, and the sudden increase in numbers at Vandenberg Air Force Base between 2000 and 2004 and at Coal Oil Point Reserve between 2002 and 2006 (Table 4).
31 Table 5. Breeding season window surveys of western snowy plover adults at selected sites along the coast of San Luis Obispo, Santa Barbara, and Ventura Counties.

Location Year
1978
-80
1989 1991 1995 1996 1997 1998 2000 2002 2003 2004 2005 2006 Atascadero
Beach
0 17 2 38 28 23 26 5 19 23 21 21 24
Morro Bay
Spit
80 94 69 34 40 39 55 87 93 114 203 205 120
Vandenbe rg
AFB 1
119 115 242 213 230 238 130 106 179 256 420 259 245
Ormond
Beach
25 24 34 20 19 34 19 10 35 19 28 21 22
Naval Base
Ventura
County
(Pt. Mugu)
82 81 59 40 49 26 47 81 85 51 75 83 79
Santa Rosa
Island 2
84 91 103 71 78 79 76 17 10 --- --- 37 19
San Miguel
Island 2
133 36 19 9 3 5 1 0 0 0 0 --- 0
San Nicolas
Island 3
71 90 78 116 104 91 90 72 69 90 79 62 96
Total 594 548 606 541 551 535 444 378 490 553 826 688 605 Unless footnoted, the source of all data is Point Reyes Bird Observatory. 1 The source of this data is the U.S. Air Force (Phil Persons) 2 The source of this data is the Nat ional Park Servi ce 3 The source of this data is the U.S. Navy
32 Los Angeles, Orange, and San Diego Counties - Western snowy plover numbers detected during window surveys declined from the 276 adults tallied during the 1978 Point Reyes Bird Observatory survey to 88 during the 1991 survey.

Subsequently the population has increased to 298 in 2006.

2. Current Breeding Distribution
The current Pacific coast breeding range of the western snowy plover extends from Damon Point, Washington, to Bahia Magdelena, Baja California, Mexico. The population is sparse in Washington, Oregon, and northern California. In 2006, estimated populations were 70 adults along the Washington coast (Pearson et al. 2006), 177-179 adults along coastal Oregon (Lauten et al. 2006b), and 2,231 adults in coastal California and San Francisco Bay (window survey including correction factor: G. Page in litt. 2006, U.S. Fish and Wildlife Service 2006a). Approximately 7 percent of the California population was observed in San Francisco Bay, and 4 percent in northern California north of the Golden Gate bridge. Along the coast of Baja California, Mexico, most nesting western snowy plovers are associated with the largest wetlands, especially Bahia San Quintin, Laguna Ojo de Liebre, and Bahia Magdelena (Palacios et al. 1994). No recent quantitative data exist on the western snowy plover population in Baja California, but it is probably roughly similar in size to the U.S. Pacific coast population.

3. Habitat Carrying Capacity
There is no quantitative information on carrying capacity of beaches for western snowy plovers. Determining carrying capacity of beaches is confounded by human use that affects the numbers of snowy plovers using the beaches. Beaches vary substantially in their structure, width, vegetation, and level of human use, complicating such a measurement.

The maximum reported breeding density of western snowy plovers is associated with the Moss Landing Wildlife Area, where since 1995 Point Reyes Bird Observatory staff have conducted intensive management specifically for western snowy plovers. These measures include predator control, removal of excessive vegetation, and operation of water control structures to maintain desired water 33 levels. With extensive management of approximately 55 hectares (138 acres) of mostly dried ponds in the Moss Landing Wildlife Area, 25 active nests, 3 pairs within 5 days of initiating nests, and 10 broods have been documented simultaneously; thus a peak of 76 nesting adults was accommodated simultaneously by 55 hectares (138 acres) of playa, or 1.4 hectares (3.6 acres) per functional pair (some of the broods were only being cared for by males) (D. George, Point Reyes Bird Observatory, pers. comm.). However, the numbers of nesting western snowy plovers at the Moss Landing Wildlife Area cannot be applied to beach areas because of the physical differences between salt pond and beach habitats and because beach habitats are typically subject to much more human disturbance.

Neither can these numbers necessarily be applied to other salt ponds (e.g., San Francisco Bay) because habitat and management opportunities differ.

D. REASONS FOR DECLINE AND CONTINUING THREATS
Overall, western snowy plover numbers have declined on the U.S. Pacific coast over the past century (see Population Status and Trends section). The subspecies faces multiple threats throughout its Pacific coast range. The reasons for decline and degree of threats vary by geographic location; however, the primary threat is habitat destruction and degradation. Habitat loss and degradation can be primarily attributed to human disturbance, urban development, introduced beachgrass (Ammophila spp.), and expanding predator populations. Natural factors, such as inclement weather, have also affected the quality and quantity of western snowy plover habitat (U.S. Fish and Wildlife Service 1993a). The following discussion is organized according to the five listing criteria under section 4(a)(1) of the Endangered Species Act.

1. The Present or Threatened Destruction, Modification, or Curtailment of Habitat or Range
a. Shoreline Stabilization and Development
The wide, flat, sparsely-vegetated beach strands preferred by western snowy plovers are an unstable habitat, subject to the dynamic processes of accretion and erosion of sand, and dependent on natural forces for replenishment and renewal. 34 These habitats are highly susceptible to degradation by construction of seawalls, breakwaters, jetties, piers, homes, hotels, parking lots, access roads, trails, bike paths, day-use parks, marinas, ferry terminals, recreational facilities, and support services that may cause direct and indirect losses of breeding and wintering habitat for the western snowy plover.

Beach stabilization efforts may interfere with coastal dune formation and cause beach erosion and loss of western snowy plover nesting and wintering habitat.

Shoreline stabilization features such as jetties and groins may cause significant habitat degradation by robbing sand from the downdrift shoreline (U.S. Fish and Wildlife Service 1996a). However, jetties also can redirect sand deposition, causing an increase in available habitat. Construction of homes, resorts, and parking lots on coastal sand dunes constitutes irrevocable loss of habitat for western snowy plovers. Urban development has permanently eliminated valuable nesting habitat on beaches in southern Washington (Brittell et al. 1976), Oregon (Oregon Department of Fish and Wildlife 1994), and California (Page and Stenzel 1981). In addition to causing direct loss of habitat, there are additional potential adverse impacts to western snowy plovers from urban development (Figure 5). Increased development increases human use of the beach, thereby increasing disturbance to nesting plovers. When urban areas interface with natural habitat areas, the value of breeding and wintering habitat to native species may be diminished by increased levels of illumination at night (e.g., building and parking lot lights); increased sound and vibration levels; and pollution drift (e.g., pesticides) (Kelly and Rotenberry 1996/1997). Beach raking removes habitat features for both plovers and their prey, and precludes nests from being established. Also, construction of residential development in or near western snowy plover habitat attracts predators, including domestic cats.
b. Resource Extraction
i. Sand Removal and Beach Nourishment
Sand is mined in coastal areas such as Monterey Bay. Mining sand from the coastal mid-dunes and surf zone can cause erosion and loss of western snowy plover breeding and wintering habitat. Sand removal by heavy machinery can disturb 35 Figure 5. New housing development next to beach at Monterey Bay, California (photo by Peter Baye, with permission).
incubating western snowy plovers, destroy their nests or chicks, and result in the loss of invertebrates and natural wave-cast kelp and other debris that western snowy plovers use for foraging. Mining of surface sand from the 1930s through the 1970s at Spanish Bay in Monterey County degraded a network of dunes by lowering the surface elevations, removing sand to granite bedrock in many locations, and creating impervious surfaces that supported little to no native vegetation (Guinon 1988).

Beach nourishment with sand can be beneficial for the western snowy plover if it results in an increase in habitat. However, unless beach nourishment projects are properly designed, they can result in changes to beach slope from redeposition of sediments by storm waves, and result in the loss of western snowy plover breeding and wintering habitat. For example, if an inappropriate size class of sand (e.g., coarser-grained sand) and range of minerals are introduced that are different from the current composition of native sand on a beach, it can alter dune slope (making it steeper or narrower), affect mobility and color of sand, decrease the abundance of beach invertebrates, and facilitate establishment of invasive exotic plants that may 36 have a competitive advantage over native plants. Feeney and Maffei (1991) investigated the color hues of the ground surface within San Francisco Bay salt ponds used as western snowy plover nesting habitat. Predominant soils were silty clay with varying amounts of humus, salt crystals, and shell fragments. They found a strong similarity between the color of the substrate in habitat preferred by western snowy plovers and the color of western snowy plover mantles (upper parts). ii. Dredging and Disposal of Dredged Materials
Dredging is detrimental to western snowy plovers when it eliminates habitat or alters natural patterns of beach erosion and deposition that maintain habitat.

Disturbances associated with dredging, such as placement of pipes, disposal of dredged materials, or noise, also may negatively affect breeding and wintering western snowy plovers. Dredging also is detrimental when it promotes water- oriented developments that increase recreational access to western snowy plover habitat (e.g., marinas, boat ramps, or other facilities to support water-based recreation). In some cases, however, dredged materials may provide important nesting habitat for western snowy plovers such as those at Coos Bay, Oregon (Wilson-Jacobs and Dorsey 1985). Western snowy plovers also have been observed using dredged material during the winter; however, these areas are not used nearly as often as the adjacent ocean beach (E.Y. Zielinski and R.W. Williams in litt. 1999).
iii. Driftwood Removal
Driftwood can be an important component of western snowy plover breeding and wintering habitat. Driftwood contributes to dune-building and adds organic matter to the sand as it decays (Washington Department of Fish and Wildlife 1995).

Additionally, driftwood provides western snowy plovers with year-round protection from wind and blowing sand. Often, western snowy plovers build nests beside driftwood, so its removal may reduce the number of suitable nesting sites.

Driftwood removed for firewood or decorative items can result in destruction of nests and newly-hatched chicks that frequently crouch by driftwood to hide from predators and people. Chainsaw noise may disrupt nesting, and vehicles used to 37 haul wood may crush nests and chicks. Removal of driftwood has been documented as a source of nest destruction at Vandenberg Air Force Base where two nests were crushed beneath driftwood dragged to beach fire sites (Persons 1994). Also, driftwood beach structures built by visitors are used by avian predators of western snowy plover chicks such as loggerhead shrikes (Lanius ludovicianus) and American kestrels (Falco sparverius), and predators of adults such as merlins (Falco columbarius) and peregrine falcons (Falco peregrinus).

Although driftwood is an important component of western snowy plover habitat, too much driftwood on a beach, which may occur after frequent and prolonged storm events, can be detrimental if there is not sufficient open habitat to induce the birds to nest.
iv. Beach Fires and Camping
Beach fires and camping may be harmful to nesting western snowy plovers when valuable driftwood is destroyed, as described above. Camping near breeding locations can cause greater impacts due to the prolonged disturbance and increased chance for possible direct mortality from associated dogs and children (S. Richardson in litt. 2001). Nighttime collecting of wood increases the risk of stepping on nests and chicks, which are difficult to see even during daylight hours.

Fires near a western snowy plover nest could cause nest abandonment due to disturbance from human activities, light, and smoke. Fires have the potential to attract large groups of people and result in an increase of garbage, which attracts scavengers such as gulls (Larus spp.) and predators such as coyotes (Canis latrans), American crows (Corvus brachyrhynchos), and common ravens (Corvus corax).

Also, after fires are abandoned, predators such as coyotes may be attracted into the area by odors lingering from the fire, particularly if it was used for cooking.

Occasionally fires escape into nearby driftwood; fire suppression activities may disturb and threaten western snowy plover nests and chicks. v. Watercourse Diversion, Impoundment, or Stabilization Water diversion and impoundment of creeks and rivers may negatively affect western snowy plover habitat by reducing sand delivery to beaches and degrading 38 water quality. Water diversions are a major threat to western snowy plovers when they impair hydrologic processes (such as migration of creek and river mouths) that maintain open habitat at river and creek mouths by retarding the spread of introduced beachgrass (Ammophila spp.) and other vegetation. Water diversion, impoundment, or stabilization activities could include construction of dams and irrigation, flood control, and municipal water development projects (Powell et al. 2002).
vi. Operation of Salt Ponds
Salt ponds of San Francisco Bay and San Diego Bay, which are filled and drained as part of the salt production process, provide breeding and wintering habitat for western snowy plovers. Dry salt ponds and unvegetated salt pond levees are used as western snowy plover nesting habitat. Ponds with shallow water provide important foraging habitat for western snowy plovers, with ponds of low and medium salinity providing the highest invertebrate densities. Ponds of high salinity have reduced invertebrate densities and therefore provide lower quality foraging habitat. Nesting western snowy plovers can be attracted to an area when ponds are drained during the breeding season, but flooding can then destroy the nests when the ponds are refilled. Also, human disturbance resulting from maintenance activities associated with the operation of commercial salt ponds can result in the loss of western snowy plovers and disturbance of their habitat. If conducted during the western snowy plover breeding season, reconstruction of salt pond levees could destroy western snowy plover nests. Maintenance activities that are conducted by vehicles, on foot, or through the use of dredging equipment could result in direct mortality or harassment of western snowy plovers (See Dredging, Pedestrian, and Motorized Vehicle sections).
c. Encroachment of Introduced Beachgrass and Other Nonnative Vegetation One of the most significant causes of habitat loss for coastal breeding western snowy plovers has been the encroachment of introduced European beachgrass (Ammophila arenaria) and American beachgrass (Ammophila breviligulata).

Foredunes dominated by introduced beachgrass have replaced the original low, rounded, open mounds formed by the native American dunegrass (Leymus mollis) 39 and other beach plants. Native dune plants do not bind sand like Ammophila spp., and thus allow for sand movement and regenerating open expanses of sand.

However, Ammophila spp. forms a dense cover that excludes many native taxa. On beaches dominated by this invasive grass, species richness of vegetation is halved, in comparison with foredunes dominated by native dune grass (Barbour and Major 1990). Similarly, American beachgrass greatly depresses the diversity of native dune plant species (Seabloom and Wiedemann 1994).

European beachgrass was introduced to the west coast around 1898 to stabilize dunes (Wiedemann 1987). Since then, it has spread up and down the coast and now is found from British Columbia to Ventura County in southern California. This invasive species is a rhizomatous grass that sprouts from root segments, with a natural ability to spread rapidly. Its most vigorous growth occurs in areas of wind- blown sand, primarily just above the high-tide line, and it thrives on burial under shifting sand. In 1988, European beachgrass was considered a major dune plant at about 50 percent of western snowy plover breeding areas in California and all of those in Oregon and Washington (J. Myers in litt. 1988).

American beachgrass is native to the East coast and Great Lakes region of North America. The densest populations of American beachgrass on the Pacific coast are currently located between the mouth of the Columbia River and Westport, Washington. Like European beachgrass, American beachgrass is dominant on the mobile sands of the foredune and rapidly spreads through rhizome fragments.

American beachgrass occurs along the entire coast of Washington, ranging from Shi Shi Beach, Washington, in the north, to Sand Lake, Oregon, in the south, although its frequency decreases markedly at the northern and southern limits of this range.

Currently, American beachgrass is the dominant introduced beachgrass species in much of the western snowy plover range in the State of Washington (Seabloom and Wiedemann 1994).

Stabilizing sand dunes with introduced beachgrass has reduced the amount of unvegetated area above the tideline, decreased the width of the beach, and increased its slope (Wiedemann 1987). These changes have reduced the amount of potential western snowy plover nesting habitat on many beaches and may hamper brood movements. In Oregon, the beachgrass community may provide habitat for western 40 snowy plover predators (e.g., skunks [Mephitis spp.], weasels [Mustela spp.], coyotes [Canis latrans], foxes [Urocyon cinereoargenteus and Vulpes vulpes.], raccoons [Procyon lotor], and feral cats [Felis domesticus]) that historically would have been largely precluded by the lack of cover in the dune community (Stern et al. 1991; K. Palermo, U.S. Forest Service, pers. comm. 1998).

In areas with European beachgrass, it has caused the development of a vegetated foredune that effectively blocks movement of sand inland and creates conditions favorable to the establishment of dense vegetation in the deflation plain, which occurs behind the foredunes (Wiedemann et al. 1969). In natural sand dunes, deflation plains consist of open sand ridges and flat plains at or near the water table.

Thus, in areas with European beachgrass, the open features that characterize western snowy plover breeding habitat are destroyed. The establishment of European beachgrass has also caused sand spits at the mouths of small creeks and rivers to become more stable than those without vegetation because of the creation of an elevated beach profile. This elevated profile, in effect, reduces the scouring of spits during periods of high run-off and storms. A secondary effect of dune stabilization has been human development of beaches and surrounding areas (Oregon Department of Fish and Wildlife 1994). This development, in turn, has reduced available beach habitat and focused human activities on a smaller area that must be shared with western snowy plovers and other shorebirds.

On the Oregon coast, the establishment of European beachgrass has produced dramatic changes in the landscape (Oregon Department of Fish and Wildlife 1994).

The spread of this nonnative species was greatly enhanced by aggressive stabilization programs in Oregon in the 1930s and 1940s (Wiedemann 1987).

European beachgrass spread profusely along the Washington coast, and was well established by the 1950s (Washington Department of Fish and Wildlife 1995). In 1988, the spread of beachgrass was termed an “increasing threat” to traditional western snowy plover nesting areas at Leadbetter Point, Washington, having become established where absent only 4 years earlier (Willapa National Wildlife Refuge 1988).

In California, there are many beaches where European beachgrass has established a foothold. These beaches include the dunes at Lake Earl, Humboldt Bay (from 41 Trinidad to Centerville Beach), MacKerricher State Beach/Ten Mile Dunes Preserve, Manchester State Beach, Bodega Bay, Point Reyes National Seashore, Golden Gate National Recreation Area, Monterey Bay, Morro Bay Beach, Guadalupe-Nipomo Dunes, and Vandenberg Air Force Base (A. Pickart in litt. 1996). Chestnut (1997) studied the spread of European beachgrass at the Guadalupe-Nipomo Dunes in San Luis Obispo County. He documented an increase in beachgrass from approximately 8 to 109 hectares (20 to 270 acres) between 1969 and 1997, and found that its rapid spread through native vegetation posed a serious threat to nesting western snowy plovers and rare plants.

In addition to the loss of nesting habitat, introduced beachgrass also may adversely affect western snowy plover food sources. Slobodchikoff and Doyen (1977) found that beachgrass markedly depressed the diversity and abundance of sand-burrowing arthropods at coastal dune sites in central California. Because western snowy plovers often feed on insects well above the high-tide line, the presence of this invasive grass may also result in loss of food supplies for plovers (Stenzel et al. 1981).

In some areas of California, such as the Santa Margarita River in San Diego County, and the Santa Clara and Ventura Rivers in Ventura County, giant reed (Arundo donax) has become a problem along riparian zones. During winter storms, giant reed is washed downstream and deposited at the river mouths where western snowy plovers nest (Powell et al. 1997). Large piles of dead and sprouting giant reed eliminate nesting sites and increase the presence of predators, which use it as perches and prey on rodents in the piles of vegetation.

Other nonnative vegetation that has invaded coastal dunes, thereby reducing western snowy plover breeding habitat, includes Scotch broom (Cytisus scoparius), gorse (Ulex europaeus), South African iceplant (Carpobrotus edulis), pampas grass (Cortaderia jubata and Cortaderia selloana) and iceplant (Mesembryanthemum sp.); shore pine (Pinus contorta) is a native plant species that has invaded coastal dunes and resulted in similar impacts to western snowy plovers (Schwendiman 1975, California Native Plant Society 1996, Powell 1996). Many nonnative weed species also occur on and along San Francisco Bay salt pond levees, resulting in unsuitable nesting habitat for western snowy plovers (J. Albertson in litt. 1999). 42 d. Habitat Conversion for Other Special Status Species It is not known whether western snowy plovers historically nested in San Francisco Bay prior to the construction of salt evaporator ponds beginning in 1860 (Ryan and Parkin 1998). However, western snowy plovers have wintered on the San Francisco Bay since at least the late 1800's, as indicated by a specimen dated November 8, 1889, in the California Museum of Vertebrate Zoology (Grinnell et al. 1918). It is possible that natural salt ponds in the vicinity of San Lorenzo once supported nesting birds, but insufficient data exist to assess this possibility (U.S.

Fish and Wildlife Service 1992). Today, however, the San Francisco Bay recovery unit supports an important western snowy plover source population, representing approximately 5 to 10 percent of the total breeding population. Feeney and Maffei (1991) observed a sizable population of western snowy plovers at the Baumberg and Oliver salt ponds during the breeding and nonbreeding seasons, suggesting that these ponds are important to western snowy plovers throughout the year. They suspected that these ponds are used by western snowy plovers as both a pre- breeding and post-breeding staging area, based on the high numbers of plovers in mid-February and in late August/September, respectively.

As part of the Recovery Plan for Tidal Marsh Ecosystems of Northern and Central California (U.S. Fish and Wildlife Service, in preparation), extensive tidal marsh restoration is identified as a recovery action for listed and other sensitive species of tidal salt marshes including the California clapper rail (Rallus longirostris obsoletus) and salt marsh harvest mouse (Reithrodontomys raviventris). A large area of San Francisco Bay salt ponds, especially within the South Bay, are proposed for tidal marsh restoration for the benefit of federally listed tidal marsh species.

Salt ponds are large, persistent hypersaline ponds that are intermittently flooded with South Bay water. Some of these ponds currently provide valuable breeding and wintering habitat for western snowy plovers. However, they occur within the historical areas of tidal salt marsh, which once dominated San Francisco Bay.

Endangered tidal marsh species would benefit from conversion of these ponds back to salt marsh; however, western snowy plovers would lose suitable nesting and wintering areas.
43 The Recovery Plan for Tidal Marsh Ecosystems of Northern and Central California will focus primarily on management of tidal marsh species, but will also provide for some areas to be maintained as managed ponds that would provide habitat for western snowy plovers and California least terns (Sternula antillarum browni). The South Bay Salt Pond Restoration Project (Philip Williams & Associates et al. 2006) has identified sites on National Wildlife Refuge and California Department of Fish and Game lands with potential for salt marsh restoration and managed ponds under a range of alternatives; the projected area of managed ponds ranges from 647 to 3,035 hectares (1,600 to 7,500 acres). Six of the plover locations identified in Appendices B and L (CA-33, CA-34, CA-39, CA-40, CA-41, CA-44) occur within the South Bay Salt Pond Restoration Project area. These six locations comprise about 60 percent of the western snowy plover locations in San Francisco Bay by area, and currently support over 90 percent of the western snowy plover population in San Francisco Bay (Strong et al. 2004, Tucci et al. 2006). In particular, several salt ponds at Eden Landing (location CA-33 and vicinity) currently support the largest population of western snowy plovers in San Francisco Bay. Distribution of plover populations and nesting sites within San Francisco Bay can fluctuate with salt pond management and availability of appropriate habitat, such that some locations identified in Appendix L are not currently occupied and other locations not mapped in Appendix L may nonetheless support breeding birds as management practices change. Thus the boundaries of San Francisco Bay locations as mapped in Appendix L reflect current and historical conditions and should be considered as flexible in the context of planning for future tidal marsh restoration. Specific localities to be managed for plovers should be coordinated with tidal marsh restoration in an integrated fashion, and thus may not be identical with the current or historical localities identified in this recovery plan.

Thus intensive management of designated ponds within the South Bay Salt Pond Restoration Project area will be crucial to achieving success in meeting western snowy plover recovery goals in San Francisco Bay. However, establishing western snowy plover populations at a variety of sites in San Francisco Bay, both within and outside the South Bay Salt Pond Restoration Project area, is advisable to minimize their vulnerability to loss (L. Trulio in litt. 2007). Potential western snowy plover habitat in San Francisco Bay outside of the South Bay Salt Pond Restoration Project area includes several sites around Alameda, Napa County, Hayward Shoreline, and 44 Crissy Field. In addition, large salt pond tracts in the South Bay remain under the ownership of Cargill; certain areas are still managed for salt production and could incidentally provide habitat for western snowy plovers, while approximately 600 hectares (1,400 acres) of ponds near Redwood City are no longer in salt production and provide an opportunity for significantly increasing western snowy plover habitat through active management. If these locations can be managed to encourage western snowy plover nesting, they may contribute substantially to meeting the overall goal of 500 breeding birds in San Francisco Bay. Western snowy plover management targets for the South Bay Salt Pond Restoration Project should take into account the habitat quality and management potential of plover habitat elsewhere in San Francisco Bay to meet overall goals for the recovery unit.

Don Edwards San Francisco Bay National Wildlife Refuge is currently planning pilot studies to assess how best to manage salt ponds for high densities of breeding western snowy plovers. Special management for western snowy plover may include intensive control of avian predators (e.g., California gull colonies, ravens); active management of water levels to control vegetation, maintain optimal salinity, and produce brine flies; timing of inundation to avoid flooding nests; and reconfiguration of shallow salt ponds with isolated islands and furrowed areas.

Locations of managed salt ponds should be planned to minimize the proximity of western snowy plover populations to landfills, gull colonies, and areas with high predator densities. Intensive management of salt ponds for western snowy plovers generally appears feasible, and plovers have been observed to opportunistically disperse among sites and use habitat that becomes suitable (V. Bloom in litt. 2005), so we expect relocation of plover nesting concentrations away from tidal marsh restoration areas to be possible, but management success should be carefully evaluated. Those alternatives with greater acreages of tidal marsh restoration (e.g., Alternative C at 90 percent tidal habitat) would require correspondingly more intensive management and reconfiguration of the remaining salt ponds (Philip Williams & Associates et al. 2006), and should be implemented gradually in conjunction with evaluation of management effectiveness for western snowy plovers.

Thus, we believe tidal marsh restoration can be compatible with the recovery of western snowy plovers and should not preclude meeting a goal of 500 breeding 45 birds in San Francisco Bay. As described below under Recovery Action 2.6, occupied salt ponds should initially be conserved. Salt marsh restoration in occupied plover habitat, particularly at densely populated sites, should be phased in after intensive adaptive management of other compensating salt pond habitat has demonstrated success in increasing plover populations. Thus habitat quality should be continually assessed so that overall western snowy plover populations in San Francisco Bay are not adversely affected by the restoration project and can increase to meet the management goal for this recovery unit.

In southern California, unless carefully planned, conversion of western snowy plover habitat to tidal salt marsh may result in loss of western snowy plover habitat.

The light-footed clapper rail (Rallus longirostris levipes) inhabits coastal tidal marshes from Santa Barbara County south to Baja California, Mexico. Several locations in Ventura, Orange, and San Diego Counties provide nesting and/or wintering habitat for western snowy plovers, but also provide high quality light- footed clapper rail habitat or represent high priority tidal marsh restoration sites in the recovery plan for the light-footed clapper rail (U.S. Fish and Wildlife Service 1985). These sites include Bolsa Chica, Agua Hedionda Lagoon, San Elijo Lagoon, San Dieguito Lagoon, and Los Penasquitos Lagoon. The Bolsa Chica wetlands were opened to tidal action in 2006, in a project combining tidal restoration work with construction of islands and sand flats for nesting of shorebirds and California least terns.

2. Overutilization for Commercial, Recreational, Scientific, or Education Purposes
Biologists and agency personnel monitor western snowy plovers to assess population status and evaluate management techniques. Additionally, nest searches at some sites allow for placement of predator exclosures that aid in hatching success. Measures to minimize disturbance from these activities include: time limits for surveys, exclosure construction and sign/rope maintenance; conducting walking surveys where feasible; and limited entries.

Egg collecting has been observed at several California nesting colonies (Stenzel et al. 1981, Warriner et al. 1986). Occasionally recreational birdwatchers also may 46 harass western snowy plovers. The significance of these factors to nesting success is uncertain but probably relatively minor.

Qualified individuals may obtain permits to conduct scientific research and population census activities on western snowy plovers under section 10(a)(1)(A) of the Endangered Species Act. Specific activities that may be authorized include:
population censuses and presence/absence surveys; monitoring of nesting activity; capturing, handling, weighing, measuring, banding, and color-marking of young and adults on breeding and wintering grounds; radio-telemetry studies; translocation studies; genetic studies; contaminant studies; behavioral, ecological, and life history studies; and placing predator exclosures around active nests. Short- term impacts of these activities may include harassment and possible accidental injury or death of a limited number of individual western snowy plovers. The long- term impacts will be to contribute to recovery of the species by facilitating development of more precise scientific information on status, life history, and ecology (U.S. Fish and Wildlife Service 1993b).

Banding birds with metal and plastic bands to identify individuals and to monitor bird populations is a common practice. However, a number of leg injuries to western snowy plovers, possibly resulting from banding, have been reported (G.

Page in litt. 2005b). These injuries include swelling and abrasion of legs possibly from sand or other particles becoming lodged between the bands and the leg. Some banding injuries appear to have resulted in foot loss and in a few instances, death of the bird. Similar injuries have been observed in piping plovers (Charadrius melodus) banded on the Atlantic coast and interior U.S., and resulted in a moratorium on banding of that species (Lingle et. al. 1999, U.S. Fish and Wildlife Service 1996a, U.S. Fish and Wildlife Service 2002). Despite leg injuries, several piping plovers were observed to successfully breed and fledge young (Lingle et. al. 1999). However, these injuries may contribute directly or indirectly to mortalities or reduce breeding performance. It should be noted that incidents of foot loss in Pacific coast western snowy plovers usually appear to result from fine fibers wrapping around the bird’s ankle, and have occurred in unbanded as well as banded individuals (J. Watkins, pers. comm. 2006). Despite risk of injuries, banding remains the best technique to study population traits such as survival, recruitment, and dispersal, and may be the most effective way to monitor populations of the 47 western snowy plover to determine effectiveness of management strategies.

Currently the percentage of banded birds range-wide that become injured from banding and the impacts of banding injuries on populations of the western snowy plover are unknown; a study was initiated in 2005 by Point Reyes Bird Observatory to assess the effectiveness of alternative banding techniques in reducing injuries and band loss (G. Page in litt. 2005b).

Concerns that color bands increase the vulnerability of western snowy plovers to predation by reducing effectiveness of camouflage do not appear to be supported by existing evidence. Because western snowy plovers crouch and flatten to the sand at the approach of avian predators, color bands are typically hidden from sight; terrestrial predators are evaded by running or taking flight at their approach (J.

Watkins, pers. comm. 2006).

3. Disease or Predation
West Nile virus, a mosquito-borne disease which can infect birds, reptiles, and mammals, has spread rapidly across the United States from the initial introduction in New England (National Audubon Society 2006). The disease has killed birds of various species in all coastal California counties since its arrival in the state in 2003 (U.S. Geological Survey 2006). In 2004 to 2006 the disease was reported from two coastal counties (Lane and Lincoln) in Oregon but has not been reported from any coastal counties in Washington (U.S. Geological Survey 2006). The deadliness of the disease varies by species; however, the virus has been identified in dead piping plovers (Charadrius melodus) and killdeer (C. vociferus), both closely related to the western snowy plover (Center for Disease Control 2004).

Since 2004 numerous western snowy plovers in southern California have been found dead or exhibited neurological signs consistent with avian botulism (M. Long in litt. 2006). Confirmation of disease diagnosis is currently pending availability of specimens for autopsy. We are currently coordinating with the USGS National Wildlife Health Center to better understand the causes of these mortalities and to develop a program for treatment of ill birds diagnosed with botulism. Additionally, 32 western snowy plovers died in 2006 from unknown causes in San Diego County (U.S. Navy in litt. 2007).
48 Predator density is a significant factor affecting the quality of western snowy plover nesting habitat (Stenzel et al. 1994). Predation can result in the loss of adults, chicks, or eggs; separation of chicks from adults is also caused by the presence of predators. Powell et al. (2002) found that predation accounted for most nest failures in 1994, 1996, and 1997, in San Diego County, California. Western snowy plovers generally cannot defend themselves or their nests against predation but must rely on antipredator adaptation, including (1) pale coloration of adults, eggs, and young, which acts as camouflage against detection by predators; (2) a skulking retreat from the nest at a predator’s approach; (3) extreme mobility and elusiveness of precocial young and; (4) maintenance of low nesting density (Page et al. 1983).

In natural ecosystems, there is a co-evolution of the predator-prey relationship, where prey species slowly evolve with evading behavior as predator species slowly evolve effective prey-capturing behavior. However, when exotic predators are introduced into the ecosystem and thrive there, they frequently occur in much higher densities and possess more effective strategies than native predators and, hence, usually have a more severe effect.

Predation, by both native and nonnative species, has been identified as a major factor limiting western snowy plover reproductive success at many Pacific coast sites. Known mammalian and avian predators of western snowy plover eggs, chicks, or adults include the following native species: gray foxes (Urocyon cinereoargenteus), Santa Rosa Island foxes (Urocyon littoralis santarosae), coyotes, striped skunks (Mephitis mephitis), spotted skunks (Spilogale putorius), raccoons, California ground squirrels (Citellus beecheyi), long-tailed weasels (Mustela frenata), American crows, common ravens (Corvus corax), ring-billed gulls (Larus delawarensis), California gulls (Larus californicus), western gulls (Larus occidentalis), glaucous-winged gulls (Larus glaucescens), gull-billed tern (Gelochelidon nilotica), American kestrels (Falco sparverius), peregrine falcons (Falco peregrinus), northern harriers (Circus cyaneus), loggerhead shrikes, merlins (Falco columbarius), great horned owls (Bubo virginianus), burrowing owls (Speotyto cunicularia), great blue herons (Ardea herodias); and the following nonnative species: eastern red foxes (Vulpes vulpes regalis), Norway rats (Rattus norvegicus), Virginia opossums (Didelphis marsupialis), domestic and feral dogs (Canis familiaris), and cats (Felis domesticus). Loss or abandonment of eggs due 49 to predation by fire ants and Argentine ants (Iridomyrmex humilis) has also been observed (Fancher et al. 2002, Powell et al. 2002).

In Oregon, nest predation by corvids (common ravens and American crows) is the major cause of nest failures. Of 63 unexclosed nests in 2005, corvid predation accounted for 22 nest failures, by comparison with 14 failures due to mammalian or unknown predators and 10 due to abandonment (Lauten et al. 2006a). Exclosures were effective in protecting nests against this threat (0 of 83 exclosed nests failed due to nest predation).

American crows have been consistently documented as a major predator on western snowy plover nests along the California and Oregon coasts (Page 1990; Persons and Applegate 1997; T. Applegate, Bioresources, pers. comm. 1999; M. Stern, The Nature Conservancy, pers. comm. 1999). At Coal Oil Point, American crows were the most frequent predator on western snowy plover nests and experimentally placed quail eggs (Lafferty et al. 2006). Populations of American crows have increased in the San Francisco Bay and central California coast over the past several decades, and are positively associated with human population density (Leibezet and George 2002).

Common ravens are known predators of western snowy plover eggs (Wilson-Jacobs and Dorsey 1985, Point Reyes Bird Observatory unpublished data, George 1997, Stein 1993, Point Reyes Bird Observatory unpublished data, J. Albertson in litt. 1999, Point Reyes Bird Observatory unpubl. data, Stern et al. 1991). Ravens have consistently been the most significant nest predator at Point Reyes, accounting for 69 percent of all predation events over 5 years and destroying approximately 50 percent of nests (Hickey et al. 1995). Hatching success at Point Reyes National Seashore increased after exclosures were used to protect western snowy plover nests from ravens in 1996. Approximately 12 percent of nests in San Diego County were destroyed by ravens (Powell et al. 1996, Powell et al. 1997). Raven populations in coastal California have significantly increased in recent decades (Leibezet and George 2002), and as their range expands they are becoming increasingly significant as a nest predator on western snowy plovers; ravens were observed to destroy nests in Monterey Bay for the first time in 2002 and 2003 (G.

Page in litt. 2004b). In northern California ravens are the single most limiting 50 factor on western snowy plover reproduction (Colwell et al. 2006). Ravens also prey on western snowy plover chicks, but not nearly to the extent that they do on eggs. However, at Point Reyes raven predation primarily affected chicks after exclosures were erected to protect snowy plover eggs (S. Allen in litt. 2004).

Gulls pose a special threat to breeding western snowy plovers because they not only depredate nests and chicks, but also usurp and trample western snowy plover nesting habitat and crush eggs (Persons and Applegate 1997, Point Reyes Bird Observatory unpublished data, Widrig 1980, J. Albertson in litt. 1999, Page et al. 1983).

The first time a gull-billed tern was found in San Diego County, California, was in 1985. Two years later they were nesting in south San Diego Bay (Unitt 2004).

Since then, the nest colony has steadily increased with an estimated 52 pairs in 2006 (Patton 2006a). Gull-billed terns have become a concern to managers of beach-nesting birds in the region. Gull-billed terns were first documented taking California least terns (presumably chicks) in south San Diego Bay in 1992 (Caffrey 1993). Patton (2006a) summarizes recent incidents of gull-billed tern predation on both terns and western snowy plovers. He notes roughly 20 to 60 California least terns and 1 to 4 western snowy plover depredations by gull-billed terns and a greater number was suspected. Although the documented number of gull-billed tern depredations on western snow plovers is considerably lower than on California least terns, it is difficult to know the full extent of gull-billed tern impacts (Patton 2006b), especially for the plovers whose nests are more dispersed and less easily monitored.

Unlike management of other avian predators, management of gull-billed terns is problematic. The local subspecies of gull-billed tern, G. n. vanrossemi, is limited to western North America (Molina and Erwin 2006, but see Unitt 2004). The subspecies nests in scattered, localized colonies and “[i]n 2003 and 2005, the entire North American population of vanrossemi gull-billed terns ranged from about 533 to 810 pairs” (Molina and Erwin 2006). This means that this predator is considerably rarer than the listed bird species upon which it preys (California least terns and western snowy plovers), which poses a conundrum for managers of western snowy plovers and California least terns (Unitt 2004). Because of the gull- 51 billed tern’s status, lethal predator control has not been used on this species since 1999 (Unitt 2004). Gull-billed terns will likely become a greater source of management concern as the local population of this species grows. Gull-billed terns have been observed at other locations of beach-nesting birds farther north from San Diego Bay, including Camp Pendleton, San Diego County (Foster 2005); Bolsa Chica, Orange County (Hamilton and Willick 1996), and Venice Beach, Los Angeles County (McCaskie and Garrett 2005).

Loggerhead shrikes are not known to take western snowy plover eggs, but do prey upon chicks and locally can have substantial effects on fledging success (Warriner et al. 1986, D. George in litt. 2001, Page et al. 1997, George 1997, Page 1988, Feeney and Maffei 1991).

Although not known to be predators of western snowy plover eggs, American kestrels are predators of chicks and possibly adults (D. George, pers. comm. 1998).

Fledging success increased from 9 to 64 percent after a kestrel unexpectedly disappeared from a western snowy plover nest site in Moss Landing Wildlife Area (Page et al. 1998). In 1997, a merlin was suspected of taking 13 banded adults within the period of a few days at Salinas River National Wildlife Refuge. Also, western snowy plover chicks and adults are among the avian prey of the peregrine falcon (B. Walton, University of California Santa Cruz, pers. comm. 1998; D.

George, pers. comm. 1998; Feeney and Maffei 1991). Northern harriers are effective predators of western snowy plover chicks and adults. In 1987, a harrier was observed hunting on the islands in the Salinas River where only approximately one third of the hatched chicks reached fledging age (Point Reyes Bird Observatory unpubl. data). At the Moss Landing Wildlife Area, fledging success dropped from 61 to 23 percent after a harrier began foraging there (Page et al. 1997). A northern harrier was seen capturing 2 to 4 western snowy plover chicks at Moss Landing salt ponds in 2000 (D. George in litt. 2001).

In recent decades, alien eastern red foxes have become a serious new predator of endangered and threatened animals in coastal habitats (Jurek 1992, Golightly et al. 1994, Lewis et al. 1993). Nonnative red foxes were imported into the southern Sacramento Valley, primarily for hunting and fur farming purposes, as early as the 1870s and experienced explosive spread in the 1970s and 1980s (Jurek 1992, Lewis 52 et al. 1993, 1995). The red fox now occurs throughout a significant portion of coastal California, including Marin, San Mateo, Santa Cruz, Monterey, San Luis Obispo, Santa Barbara, Ventura, Orange, and Los Angeles Counties (California Department of Fish and Game 1994). It also occurs at Monterey Bay (G. Page in litt. 1988) and San Francisco Bay (Harding et al. 1998), including the additional San Francisco Bay area counties of Napa, Solano, Contra Costa, Alameda, and Santa Clara (California Department of Fish and Game 1994). Red foxes also are present in some areas of coastal Oregon where western snowy plovers breed (D.

George in litt. 2001, Lauten et al. 2006b).

Red foxes have been identified as a significant predator of western snowy plover eggs in the Monterey Bay area, where they are suspected of also preying on adults and chicks. On Monterey Bay beaches, red fox depredation of western snowy plover eggs resulted in a decline in clutch hatching rate of 30 percent from 1984 to 1990. After exclosures and mammalian predator control came into use to protect nests around Monterey Bay, annual clutch hatching rates have climbed from 43 to 68 percent (Neuman et al. 2004).

Predation of western snowy plover nests and chicks by red fox have been documented at Bandon Beach, New River and other portions of OR-15 on the Oregon coast. Biologists have documented red fox tracks around western snowy plover nest exclosures and have followed fox tracks back to dens located within western snowy plover nest areas. As part of the emergency response to the New Carissa oil spill in February 1999, a predator program was implemented. Animal and Plant Health Inspection Service (APHIS) Wildlife Services Division personnel removed 17 red fox from the New River area over a 3 month period (S. Richardson in litt. 2001). Ongoing predator management since 2002 has removed an average of 15 foxes per year from Bandon Beach/New River (Lauten et al. 2006b).

The U.S. Department of Agriculture, Wildlife Services Branch, has been involved in predator damage management for protection of threatened and endangered species for over 10 years in California. The management of nonnative red foxes has become a controversial issue in many areas of California, particularly in coastal habitats near urban areas (California Department of Fish and Game 1994). In November 1998, California voters approved Proposition 4, which banned the use of 53 leghold traps in California. In February 1999, the U.S. District Court issued a Preliminary Declaratory Relief Order, which allows the use of padded leghold traps on Federal and non-Federal lands for the purpose of protecting threatened or endangered species. Trapping of nonnative and native predators of western snowy plovers will therefore not be affected by Proposition 4 (J. Albertson in litt. 1999).

Coyotes are known predators of western snowy plover eggs in the Pismo Beach/Santa Maria River area of San Luis Obispo County (T. Applegate, pers. comm. 1996). They are the main nest predator of eggs on Vandenberg Air Force Base where they were the cause of 43 percent of all clutch losses attributed to predators from 1994 to 1997 (Persons and Applegate 1997). At Vandenberg Air Force Base, coyotes may be attracted to marine mammal carcasses on the beach early in the western snowy plover nesting season (Page and Persons 1995).

Coyotes also have been identified as predators of western snowy plover nests at Mono Lake, California (Page et al. 1983).

Striped skunks have been recorded as predators of western snowy plover eggs (Hickey et al. 1995, George 1997, Page et al. 1997, Hutchinson et al. 1987, Stein 1993, Stern et al. 1991). Skunks were believed to be the main cause of nest loss on Morro Bay Spit in 1987, the only year that the reproductive success of western snowy plovers has been monitored at that location (Hutchinson et al. 1987).

Persons and Ellison (2001) reported that the striped skunk was the predominant predator of nests at Morro spit, destroying 87 percent of depredated nests in 2000.

Domestic and feral cats are widespread predators. The threat of predation of western snowy plovers by cats increases when housing is constructed near western snowy plover breeding habitat. As natural-appearing beaches continue to be surrounded by urban areas, western snowy plovers will increasingly be subjected to this predator in the future. Predation by cats is difficult to measure because of the difficulty in finding evidence of bird remains, but they are known to take western snowy plover adults and eggs (B. Farner, pers. comm. in Powell and Collier 1994;

Page 1988 ends

Predation, while predominantly a natural phenomenon, is exacerbated through the introduction of nonnative predators and unintentional human encouragement of 54 larger populations of native predators. Elevated predation pressures result from landscape-level alterations in coastal dune habitats which, in turn, now support increased predator populations within the immediate vicinity of nesting habitat for western snowy plovers. Urbanization benefits red fox population growth by eliminating coyotes, which are the red fox’s most common native predator and competitor; by providing ready sources of food, water and denning sites; and by aiding dispersion of foxes into new areas. Red foxes disperse readily in urban areas because there are no predators besides the domestic dog. Red foxes traverse most urban habitats, and readily cross busy highways and travel long distances underground through culverts (Lewis et al. 1993). Other predators, such as corvids, attracted by the presence of human activities (e.g., improper disposal of trash), may frequent beaches in increasing numbers. Gulls have greatly expanded their range and numbers, especially along the United States portion of the Pacific coast, as a result of human-supplied food sources (trash, fish offal, and dumps). Thousands of California gulls now breed in the southern part of San Francisco Bay, where only a few were present in the early 1980s (J. Albertson in litt. 1999). This population growth is attributed largely to the increase in landfills along the Bay within the last 20 years. Also, crows and ravens forage at landfills. Buick and Paton (1989) found that losses of hooded plover (Charadrius rubricollis) nests with human footprints around them were higher than at those without footprints, suggesting “that scavenging predators may use human footprints as a visual cue in locating food.” Beach litter and garbage also attract predators such as skunks and coyotes (e.g., N.

Read in litt. 1998). Unnatural habitat features such as landscaped vegetation (e.g., palm trees), telephone poles, transmission towers, fences, buildings, and landfills near western snowy plover nesting areas attract predators and provide them with breeding areas (e.g., J. Buffa in litt. 2004). These alterations all combine to make the coastal environment more conducive to various native and nonnative predators that adversely affect western snowy plovers.

Substantial evidence exists that human activities are affecting numbers and activity patterns of predators on western snowy plovers. For example, increased depredation of western snowy plover nests by ravens at the Oliver Brothers salt pond, California, may be an indirect adverse impact of nearby installation of light structures by the California Department of Transportation and high-tension power lines by the Pacific Gas and Electric Company, thereby creating corvid nesting sites 55 (G. Page, Point Reyes Bird Observatory, pers. comm. 1997). Raven nests have also been discovered by National Wildlife Refuge biologists in transmission towers near other snowy plover nesting areas managed by the Don Edwards San Francisco Bay National Wildlife Refuge in Warm Springs, Alviso, and Mountain View (J. Buffa in litt. 2004). On the Oregon coast, predation risk by mammals has increased as a result of the spread of European beachgrass, Scotch broom, and shore pine, which has transformed vast areas of open sand into dense grass-shrub habitat, providing excellent habitat for native and nonnative mammalian predators, such as skunks, raccoons, foxes, and feral cats (Stern et al. 1991). At Vandenberg Air Force Base, coyote predation can be exacerbated by human presence when trash or debris is left behind (N. Read in litt. 1998).

Signing and fencing of restricted areas on the beach may provide perches for avian predators of western snowy plover adults or chicks (Hallett et al. 1995). Although signs and fences are important conservation tools in many areas, land managers need to be aware that modifications to them may be necessary to deter predators in some circumstances.

4. The Inadequacy of Existing Regulatory Mechanisms
The western snowy plover is protected by the Federal Migratory Bird Treaty Act (16 U.S.C. 703 et seq.) and, in each state, by State law as a nongame species. The western snowy plover's breeding habitat, however, receives only limited protection from these laws (e.g., the Migratory Bird Treaty Act prohibition against taking "nests"). Listing of the western snowy plover under State endangered species laws generally provides some protection against direct take of birds, and may require State agencies to consult on their actions, but may not adequately protect habitat.

State regulations, policies, and goals include mandates both for protection of beach and dune habitat and for public recreational uses of coastal areas; consequently they may conflict with protection of western snowy plovers in some cases. Section 404 of the Clean Water Act (33 U.S.C. 1251 et seq.) and section 10 of the Rivers and Harbors Act (33 U.S.C. 403) are the primary Federal laws that could provide some protection of nesting and wintering habitat of the western snowy plover that is determined by the U.S. Army Corps of Engineers (Corps) to be wetlands or historic navigable waters of the United States. These laws, however, would apply to only a 56 small fraction of the nesting and wintering areas of the western snowy plover on the Pacific coast. Aside from the Migratory Bird Treaty Act, western snowy plovers have no protection status in Mexico.

To effectively recover the western snowy plover, it is necessary to develop participation plans among cooperating agencies, landowners, and conservation organizations to assure protection and appropriate management of breeding, wintering, and migration areas. Since listing of the western snowy plover in 1993, several local working groups have been developed and local governments and State and Federal agencies have cooperated extensively to implement a wide variety of western snowy plover conservation actions. These partners continue to work to implement appropriate management of coastal areas for recovery of the western snowy plover. These conservation efforts and the environmental policies of State and Federal agencies are described in greater detail in the Conservation Efforts section, below.

For additional discussion of regulatory mechanisms and management actions taken by California State Parks and other entities, see U.S. Fish and Wildlife Service (2006a).

5. Other Natural or Manmade Factors Affecting Their Continued Existence a. Natural Events
Western snowy plover breeding and wintering habitat is subject to constant change from weather conditions. Stenzel et al. (1994) reported that the quality and extent of western snowy plover nesting habitat is variable in both the short- and long-term.

Coastal beaches increase in width and elevation during the summer through sand deposition, making marginal beaches more suitable for nesting later in the season.

Over the longer term, an increase or decrease in habitat quality may occur after several years of winter storms. Based on the amount of flooding, the availability of dry flats at the edges of coastal ponds, lagoons, and man-made salt evaporators also varies within and between seasons. Therefore, the number of western snowy plovers breeding in some areas may change annually or even over one breeding season in response to natural alterations in habitat availability (Stenzel et al. 1981). 57 Because most western snowy plover nesting areas occur on unstable sandy substrates, nest losses caused by weather-related natural phenomena commonly occur. High tides and strong winds cause many nest losses. Events such as extreme high tides (Wilson 1980, Stenzel et al. 1981), river flooding (Stenzel et al. 1981), and heavy rain (Wilson 1980, Warriner et al. 1986, Page 1988) have been reported to destroy or wash away nests. The annual percentage of total nest losses attributed to weather-related phenomenon has reached 15 to 38 percent at some locations (Wilson 1980, Warriner et al. 1986, Page 1988).

Stormy winters can adversely affect the western snowy plover. It is suspected that the severe storms occurring during the El Niño atmospheric and oceanic phenomenon of the winter of 1997/1998 caused a 10 to 30 percent decline in the 1998 western snowy plover breeding population, depending on the coastal region.

In all monitored recovery units, the number of breeding birds in 1998 was lower than in the 1997 nesting season. Additionally, a very wet spring resulted in a later than normal breeding initiation and fewer nesting attempts.

The western snowy plover population naturally varies, both spatially and temporally, because of natural changes in weather and habitat conditions from year to year. However, as described above, human influences over the past century (e.g., habitat destruction, invasion of introduced beachgrass, and elevated predation levels) have reduced the western snowy plover’s ability to respond to these natural perturbations.
b. Disturbance of Breeding Plovers by Humans and Domestic Animals The coastal zone of the United States, including both open coastal areas and inland portions of coastal watersheds, is home to over one-third of the U.S. human population, and that proportion is increasing (U.S. Fish and Wildlife Service 1995a). The southern California coastal area, which constitutes the central portion of the western snowy plover’s coastal breeding range, attracts large crowds on a regular basis (Figure 6). The increasing level of human recreation was cited as a major threat to the breeding success of the Pacific coast population of the western snowy plover at the time of listing (U.S. Fish and Wildlife Service 1993a). 58 Figure 6. Recreationists at Salt Creek Beach, California (photo by Ruth Pratt, with permission).
i. Pedestrians
Pedestrians (e.g., beach walkers and joggers) can cause both direct mortality and harassment of western snowy plovers. Pedestrians on beaches may crush eggs or chicks and chase western snowy plovers off their nests. Separation of western snowy plover adults from their nests and broods can cause mortality through exposure of vulnerable eggs or chicks to heat, cold, blowing sand, and/or predators.

Pedestrians have been known to inadvertently step on eggs and chicks, deliberately take eggs from nests, and remove chicks from beaches, erroneously thinking they have been abandoned. People also may cause broods of western snowy plovers to run away from favored feeding areas. These effects are described in more detail below. Trash left on the beach by pedestrians also attracts predators. In addition to public pedestrians, military personnel using the beach for maneuvers, boat launches, and landings have the potential to similarly cause adverse impacts to western snowy plovers.
59 Beach-related recreational activities that are concentrated in one location (e.g., sunbathing, picnicking, sandcastle building, birding, and photography) can negatively affect incubating adult western snowy plovers when these activities occur too close to their nests. Recreational activities that occur in the wet sand area (e.g., sand sailing) can adversely affect western snowy plovers when they disturb plover adults or broods, which feed at the edge of the surf along the wrack line.

Recreational activities that occur in or over deep water (such as the beach- and water-oriented activities of surfing, kayaking, wind surfing, jet skiing, and boating, and the coastal-related recreational activity of hang gliding) may not directly affect western snowy plovers; however, they can potentially be detrimental to western snowy plovers when recreationists use the beach to take a break from these activities, or as access, exit, or landing points.

Concentrations of people may deter western snowy plovers and other shorebirds from using otherwise suitable habitats. Anthony (1985) found that intensive human activity at Damon Point had a “bracketing effect” on the distribution of nesting western snowy plovers, confining their breeding activity to a section of the spit and precluding their regular use of otherwise suitable habitat. Fox (1990) also found that western snowy plovers avoided humans at Damon Point, and the presence of fishermen and beachcombers kept them hundreds of yards away from potential habitat. Because early-nesting western snowy plovers have narrower beaches from which to select nest locations, recreational use may be more concentrated in the limited habitat available. Also, repeated intrusions by people into western snowy plover nesting areas also may cause birds to move into marginal habitats where their chances of reproductive success are reduced. Studies of the Atlantic coast population of the piping plover (Charadrius melodus), an eastern species with habitat requirements very similar to the snowy plover, indicate that some piping plovers that nest early in the season are forced to move elsewhere when human use becomes too intense (Cairns and McLaren 1980). These authors concluded that piping plovers that nest early, before beaches become heavily used for recreation, “cannot predict and avoid reproductive failure in habitats that otherwise appear suitable to them.” Burger (1993) observed that piping plovers, in response to human disturbance, spent more energy on vigilance and avoidance behavior at the expense of foraging activity, and sometimes abandoned preferred foraging habitat. 60 Page et al. (1977) observed western snowy plovers’ response to human disturbance at two coastal beaches where normal beach use ranged from light to heavy. The study included 156 hours of observation at 15 western snowy plover nests. At Point Reyes, they found that pedestrians disrupt incubation of nests. When humans approached western snowy plovers, adults left their nests 78 percent of the time when people were within 50 meters (164 feet) and 34 percent of the time when people were over 100 meters (328 feet). They also found that western snowy plovers’ reaction to disturbance by humans varied, ranging from one bird remaining off the nest for less than 1 minute when a person walked within 1 meter (3 feet) of the nest on a heavily-used beach to another western snowy plover leaving the nest when three people were 200 meters (656 feet) away on a less-used beach. They noted that “birds exposed to prolonged human activity near the nest seemed to become accustomed to it.” It has been speculated that predators of western snowy plovers may benefit from a decline in wariness by western snowy plovers nesting on beaches that are subject to ongoing high levels of human disturbance (Persons and Applegate 1997).

Lafferty (2001) observed western snowy plovers’ response to people, pet dogs, equestrians, crows and other birds. Observations were made at Devereux Slough in Santa Barbara County, Santa Rosa Island, San Nicolas Island, and Naval Base Ventura County (Point Mugu). This study found that western snowy plover are most frequently disturbed when approached closely (within 30 meters) by people and animals. The most intense disturbance (causing the western snowy plover to fly away) were in response to crows, followed by horses, dogs, humans, and other birds. Lafferty (2001) created a management model based on his findings and estimated flight response disturbances under different scenarios. The model predicted a reduced disturbance response for buffer zones of 20 to 30 meters.

Fahy and Woodhouse (1995) quantified the levels of recreational disturbance, their effect on western snowy plovers, and the effectiveness of the Linear Restriction Program at Ocean Beach, Vandenberg Air Force Base in 1995. Under this program signs directed visitors not to cross from the outer beach into the Linear Restriction area (inland of mean high tide mark, in dune habitat used by western snowy plovers). Seventy percent of all disturbances were in compliance with restriction warning signs. The disturbance types that were most and least frequently in 61 compliance with the boundary were joggers or walkers and stationary visitors, respectively. The closer the disturbance occurred to the plover, the more severe the plover response. All-terrain vehicles caused the most significant alert and flight behaviors by western snowy plovers, even though they were in compliance with the Linear Restriction. The disturbance types that caused incubating western snowy plovers to flush from their nests most frequently were joggers and walkers, followed by joggers or walkers with dogs off leash, and stationary visitors. The disturbance types that kept incubating western snowy plovers off their nests for the longest period of time were stationary visitors and surf fishermen, probably because of the duration of these stationary disturbances that occurred close to nests.

Weekends accounted for 60 percent of all disturbances. The enforcement personnel appeared to have a limited presence; their presence was documented during only 14 percent of all identified disturbances.

Hoopes et al. (1992) quantified human use and disturbance to piping plovers in Massachusetts during the 1988 and 1989 nesting seasons. They found pedestrians caused piping plovers to flush or move at an average distance of 23 meters (75 feet). Pedestrians within 50 meters (164 feet) of the birds caused piping plovers to stop feeding 31 percent of the time.

Point Reyes Bird Observatory found that management actions that included exclusion zones around nesting areas, seasonal closure to dogs, and active weekend docent programs reduced mortality of chicks and eggs during the weekend such that the weekend and weekday mortality was the same (Peterlein and Roth 2003).

At the Pajaro River mouth in California, at least 14 percent of western snowy plover clutches were destroyed by being driven over, stepped on, or deliberately taken by people (Warriner et al. 1986). Since exclosures have been used to protect nests at the Pajaro River mouth and other locations at Monterey Bay, a few nests have still been deliberately destroyed by vandals in most years (Point Reyes Bird Observatory unpublished data). At South Beach, Oregon, the number of western snowy plovers declined from 25 in 1969 to 0 in 1981 when a new park was constructed next to the beach and the adjacent habitat became more accessible to vehicles and people (Hoffman 1972 in Oregon Department of Fish and Wildlife 1994).
62 At Vandenberg Air Force Base, western snowy plover monitoring during 1993 at South Beach (where recreational use was high) and North Beach (where recreational use was low) found the rate of nest loss caused by humans differed markedly: 24.3 percent of South Beach nests were lost compared to only 3.0 percent of North Beach nests (Persons 1994). Persons and Applegate (1997) reported that “rates of reproductive success, combined for 1994 through 1997, were substantially higher on North Beach than on South Beach.” This difference occurred despite the fact that nesting habitat was posted as off-limits during the nesting season in 1994. However, at that time restrictions were new and not strictly enforced (R. Dyste in litt. 2004). Since 2000, public access has been restricted and fully enforced by Vandenberg Air Force Base personnel. Additionally, Santa Barbara County-supported volunteer docents were present at Surf Station (within Vandenberg Air Force Base) during the 2001-2003 plover breeding seasons when the beach was open for public access. In 2003, plover monitors did not document the loss of any nests within Surf Station Beach as a result of trampling by humans (R. Dyste in litt. 2004).

Loss of western snowy plover chicks also may occur because of human activities.

The number of young produced per nesting attempt increased from 0.75 in disturbed habitat to 2.0 for nests free of disturbance at Willapa National Wildlife Refuge, Washington (Saul 1982). At Vandenberg Air Force Base, the 1997 fledging success of western snowy plovers was 33 to 34 percent on North Beach where recreational activity is restricted and only 12 percent on South Beach where recreational use is high (Persons and Applegate 1997). In 1999 and 2000, Ruhlen et al. (2003) found that increased human activities on Point Reyes beaches had a negative effect on western snowy plover chick survival. In both 1999 and 2000, western snowy plover chick loss was about three times greater on weekends and holidays than on weekdays. In most coastal areas, beach visitation in summer months is much higher on weekends and holidays than on weekdays.

Flemming et al. (1988) measured the effects of human disturbance on reproductive success and behavior of piping plovers in Nova Scotia. To assess human disturbance, they recorded positions of people, pedestrian tracks, and vehicle tracks, then defined classes based on visits per week. They found significantly fewer young survived in areas of high versus low disturbance; humans elicited a 63 significantly higher response level from adult piping plovers than did predators or nonpredatory species; chicks fed less and were brooded less when humans were within 160 meters (525 feet); and chick peck rate during feeding was lower when humans were present. They speculated that because chicks shifted from feeding and energy conservation activities to vigilance and cryptic predator avoidance behaviors, their energy reserves would be depleted, making them more susceptible to predators and inclement weather. They postulated that a decline in piping plover abundance in Nova Scotia could be caused by human disturbance altering chick behavior. Fewer chicks survived to 17 days in areas heavily disturbed by humans.

Schultz and Stock (1993) studied the effects of tourism on colonization, distribution, and hatching success of Kentish plovers (Charadrius alexandrinus alexandrinus), a Eurasian subspecies of the snowy plover, at the Wadden Sea in Germany. They measured disturbance intensity by counting and mapping tourists on 50 days from April to July, during times of peak human activity (1500 to 1600 hours) and in intervals of 30 minutes throughout other days. An index of person- hours per area per day was calculated. They found that Kentish plovers did not colonize heavily-disturbed areas and that resting and sunbathing people were apparently more disruptive than walking people because the latter generally followed the high-tide line. Clutch losses were lowest in areas with little disturbance and highest in areas with heavy disturbance. They indicated that hatching success in highly disturbed areas, even with optimal habitat, is as low as in poor habitat with a low level of disturbance.
ii. Dogs
Dogs on beaches can pose a serious threat to western snowy plovers during both the breeding and nonbreeding seasons. Unleashed pets, primarily dogs, sometimes chase western snowy plovers and destroy nests. Repeated disturbances by dogs can interrupt brooding, incubating, and foraging behavior of adult western snowy plovers and cause chicks to become separated from their parents. Pet owners frequently allow their dogs to run off-leash even on beaches where it is clearly signed that dogs are not permitted or are only permitted if on a leash. Enforcement of pet regulations on beaches by the managing agencies is often lax or nonexistent. 64 A number of examples of disruptive ways that dogs affect western snowy plovers have been noted at beaches in Monterey County (Marina State Beach), Santa Cruz County (Laguna, Scott Creek, and Seabright Beaches) and San Mateo County (Half Moon Bay and Pacifica Beaches) (D. George, pers. comm. 1997). Incubating birds have been flushed from nests by dogs, including nests located inside areas protected by symbolic fencing. Dogs also have displaced adults from nests with newly- hatched chicks. Roosting and feeding flocks, as well as individual birds, have been deliberately and persistently pursued by dogs. At Laguna Creek Beach, Zmudowski State Beach, and Salinas River State Beach, dogs partially or entirely destroyed western snowy plover nests which were in several cases, protected with symbolic fencing (D. George, pers. comm. 1997; Point Reyes Bird Observatory unpublished data; G. Page, pers. comm. 1998). Feral dogs are suspected to have disturbed western snowy plover nests and chicks on San Francisco Bay salt ponds (J. Albertson in litt. 1999).

Even when not deliberately chasing birds, dogs on a beach may disturb western snowy plovers and other shorebirds that are roosting or feeding. Page et al. (1977) found that western snowy plovers flushed more frequently and remained off their nests longer when a person was accompanied by a dog than when alone. They collected data during 156 hours of observation at 15 nests at Point Reyes, California, and found the following distances at which western snowy plovers flushed from their nests as a result of disturbance by people with dogs. Within 50 meters (164 feet), people with dogs caused flushing 100 percent of the time. At a distance of over 100 meters (328 feet), people with dogs caused flushing 52 percent of the time (Page et al. 1977). Fahy and Woodhouse (1995) found that joggers or walkers with off-leash dogs caused a significantly greater number of avoidance responses from western snowy plovers than other types of disturbances at Ocean Beach, Vandenberg Air Force Base, California. Lafferty’s (2001) management model predicted that intense disturbances could be dramatically reduced by removing dogs.

At wintering sites such as Ocean Beach in San Francisco, California, off-leash dogs have caused frequent disturbance and flushing of western snowy plovers and other shorebirds. Off-leash dogs chase wintering western snowy plovers at this beach and have been observed to regularly disturb and harass birds (P. Baye, U.S. Fish 65 and Wildlife Service, pers. comm. 1997). Observations by National Park Service volunteers suggest that unleashed pets represent the most significant recreational threat to wintering western snowy plovers and migratory shorebirds at Ocean Beach, because of the prolonged and repeated disturbance created when they chase birds (Hatch 1997). In 1995 and 1996, during 45 hour-long observations of wintering flocks of western snowy plovers at Ocean Beach, western snowy plovers responded by moving in 73 percent of 74 instances when dogs with or without people approached to within 15 meters (50 feet) (Golden Gate National Recreation Area unpublished data). When shorebirds are flushed, they must spend more energy on vigilance and avoidance behaviors at the expense of foraging and resting activity (Burger 1993, Hatch 1997). Disruption of foraging and roosting may result in decreased accumulation of energy reserves necessary for shorebirds to complete the migration cycle and successfully breed (Burger 1986, Pfister et al. 1992). Dog disturbance at wintering and staging sites, therefore, may adversely affect individual survivorship and fecundity, thereby affecting the species at the population level.
iii. Motorized Vehicles
Unrestricted use of motorized vehicles on beaches is a threat to western snowy plovers and their habitat. Motorized vehicles may affect remote stretches of beach where human disturbance would be slight if access were limited to pedestrians. The magnitude of this threat is variable, depending on level of use and type of terrain covered. Use of motor vehicles on coastal dunes may also be destructive to dune vegetation, especially sensitive native dune plants.

Driving vehicles in breeding habitat may cause destruction of eggs, chicks, and adults, abandonment of nests, and considerable stress and harassment to western snowy plover family groups (G. Page, pers. comm. 1997; J. Myers in litt. 1988; J. Price in litt. 1992; Stern et al. 1990; Casler et al. 1993; S. Richardson, pers. comm. 1998; Widrig 1980). In addition to recreational vehicles, vehicles used for military activities have also caused western snowy plover mortality (Powell et al. 1995, 1997; Persons 1994).
66 Driving motor vehicles at night seems to be particularly hazardous to western snowy plovers. Drivers of all-terrain vehicles at night have run over and killed western snowy plover adults at Vandenberg Air Force Base, and State park ranger patrol vehicles have crushed western snowy plover chicks at Oceano Dunes State Vehicular Recreation Area during night patrols (R. Mesta in litt. 1998).

On the Eel River gravel bars, vehicle use (including motorcycles, ATVs, and full- size 4x4s) has resulted in the crushing of nests and disturbance to nesting plovers (Colwell et al. 2006).

Western snowy plover adults and chicks have been observed using tire tracks and human footprints for loafing at Camp Pendleton and Naval Amphibious Base Coronado (Powell and Collier 1994). This behavior increases their chances of being run over. Western snowy plover chicks also may have difficulty getting out of tire ruts, thereby increasing their likelihood of being run over. Their cryptic coloring and habit of crouching in depressions like tire tracks makes western snowy plover chicks especially vulnerable to vehicular traffic. In Massachusetts, between 1989 and 1997, a total of 25 piping plover chicks and 2 adults were found dead in off-road vehicle tire ruts on the upper beach between the mean high tide line and the foredune (U.S. District Court of Massachusetts 1998).

Hoopes et al. (1992) found off-road vehicles caused piping plovers to flush or move at an average distance of 40 meters (131 feet). Off-road vehicles within 50 meters (164 feet) of the birds caused piping plovers to stop feeding 77 percent of the time.

While most responses by piping plovers to off-road vehicles resulted in movement by the birds, they observed three instances where the plovers “froze” in response to the off-road vehicles. Both types of responses have a negative impact on plovers through either disturbance, interruption of feeding behavior, or increasing the risk that piping plovers will be hit or crushed by vehicles.

At wintering sites, disturbance from motorized vehicles may harass western snowy plovers and disrupt their foraging and roosting activities, thereby decreasing energy reserves needed for migration and reproduction. When motorcycles, most of which were in the wet sand zone, were driven at high speed along Ocean Beach in San 67 Francisco, Hatch (1997) observed that western snowy plovers and other shorebirds were continually disturbed and often took flight.
iv. Beach Cleaning
Removal of human-created trash on the beach is desirable to reduce predation threats by eliminating food for predators of western snowy plovers; however, the indiscriminate nature of mechanized beach-cleaning adversely affects western snowy plovers and their habitat. Mechanized beach cleaning can be dangerous to western snowy plovers by crushing their clutches and chicks or causing prolonged disturbance from the machine’s noise. Also, this method of beach cleaning removes the birds’ natural wrackline (area of beach containing seaweed and other natural wave-cast organic debris) feeding habitat, reducing the availability of food.

Kelp and driftwood, with their associated invertebrates, are regularly removed and the upper layer of sand is disturbed. Beach grooming also alters beach topography, removes objects associated with western snowy plover nesting, and prevents the establishment of native beach vegetation (J. Watkins in litt. 1999). In all of Los Angeles County and parts of Ventura, Santa Barbara, and Orange Counties, California, entire beaches are raked on a daily to weekly basis. Large rakes, with tines 5 to 15 centimeters (2 to 6 inches) apart, are dragged behind motorized vehicles from the waterline to pavement or to the low retaining wall bordering the beaches (Stenzel et al. 1981). Even if human activity was low on these beaches, grooming activities completely preclude the possibility of successful western snowy plover nesting (Powell 1996).
v. Equestrian Traffic
Most equestrian use on beaches is directed to wet-sand areas. However, during high tide periods, horseback riders on the beach sometimes enter coastal dunes or upper beach areas (Figure 7), where they may crush clutches or disturb western snowy plovers (Point Reyes Bird Observatory unpublished data, Page 1988, Persons 1995, Craig et al. 1992, Woolington 1985).
68 Figure 7. Equestrians on beach (photo by U.S. Forest Service, with permission).
vi. Fishing
Impacts on western snowy plover nesting may be associated with surf fishing and shellfish harvesting in and near western snowy plover habitat. The improper disposal of offal (waste parts of fish), bait, and other litter attracts crows, ravens, and gulls, which are predators of western snowy plover eggs and chicks. Also, western snowy plovers may become entangled in discarded fishing lines (G. Page, pers. comm. 1998).

Surf fishing is a commercial enterprise in many coastal locations, including the ocean smelt fishery in northern California (C. Moulton in litt. 1997). Recreational surf fishing occurs throughout the California coast. In Humboldt County, California, Redwood National and State Parks have proposed allowing beach vehicle use, by annual permit, for commercial fishing and tribal fishing/gathering on Gold Bluffs Beach, Freshwater Spit, and Crescent Beach (J. Watkins in litt. 1999). In the State of Washington, the most popular season for surf fishing is April through July (Washington Department of Fish and Wildlife 1995). At present, 69 demand for surf perch fishing is relatively low in Oregon. However, the Oregon Department of Fish and Wildlife is promoting a surf perch fishery to lessen the demand for anadromous fishing. This fishery would increase vehicle driving to remote and relatively undisturbed sites used by western snowy plovers (K. Palermo in litt. 1998a).

Because the earliest western snowy plover clutches in Washington are laid between mid-April and mid-May, harvesting of razor clams during the mid-March to mid- May clamming season may have adverse impacts on prospecting or nesting western snowy plovers. Clammers near nesting areas may disturb adults and chicks; human activity in feeding areas may restrict western snowy plover foraging activity, and increased motorized traffic may increase the risk of nest and chick loss (Washington Department of Fish and Wildlife 1995). However, observations of western snowy plover and human activities during the spring 1995 razor clam season showed clamming had no visible impact on western snowy plovers where clamming intensity was low (Kloempken and Richardson 1995). Instances of trespassing into the western snowy plover protection area were noted; however, movement of the western snowy plover protection area boundary about 327 meters (1,073 feet) west of its previous location seemed to benefit the birds by providing more space between them and pedestrian and vehicular disturbances. vii. Fireworks
Fireworks are highly disturbing to western snowy plovers. All western snowy plovers flushed from Coal Oil Point Reserve during a nearby July 4, 2005, fireworks display (C. Sandoval, University of California Santa Barbara, pers. comm. 2005). At Del Monte Beach, California, a western snowy plover chick hatched on July 4, 1996, within an area demarcated by symbolic fencing, and was abandoned by its parents after a fireworks display. Disturbance from the noise of the pyrotechnics is exacerbated by disturbance caused by large crowds attracted to fireworks events. California Department of Parks and Recreation staff estimated that 6,000 people visited Del Monte Beach on that day. Because of the extensive disturbance, the adult western snowy plovers left the nest site with two chicks, abandoned the third chick, and were not seen again (K. Neuman, California Department of Parks and Recreation, pers. comm. 1997). During July 4, 1992, 70 observations of piping plovers that nest on the Breezy Point Cooperative and adjacent beaches of Gateway National Recreation Area in Queens, New York, the birds were disturbed by fireworks displays (Howard et al. 1993). Management recommendations for this area included prohibition of fireworks in or near the fenced and posted nesting and brood-rearing areas.
viii. Kite Flying and Model Airplanes
Biologists believe plovers perceive kites as potential avian predators (Hoopes et al. 1992, Hatch 1997). The reaction of western snowy plovers to kites at Ocean Beach in San Francisco, California, “ranged from increased vigilance while roosting in close proximity to the kite flying, to walking or running approximately 10 to 25 meters (33 to 82 feet) away and resting again while remaining alert” (Hatch 1997).

It is expected that stunt-kites would cause a greater response from western snowy plovers than traditional, more stationary kites. Stunt kites include soaring-type, two-string kites with noisy, fluttering tails, which often exhibit rapid, erratic movements.

Hoopes et al. (1992) found that piping plovers are intolerant of kites. Compared to other human disturbances (i.e., pedestrian, off-road vehicle, and dog/pet), kites caused piping plovers to flush or move at a greater distance from the disturbance, to move the longest distance away from the disturbance, and to move for the longest duration. Piping plovers responded to kites at an average distance of 85 meters (279 feet); moved an average distance of over 100 meters (328 feet); and the average duration of the response was 70 seconds.

It is expected that model airplanes may also have a detrimental impact to western snowy plovers because western snowy plovers may perceive them as potential predators (Hatch 1997).
ix. Aircraft Overflights
Low-flying aircraft (e.g., within 152 meters (500 feet) of the ground) can cause disturbances to breeding and wintering western snowy plovers. Hatch (1997) found that all types of low-flying aircraft potentially may be perceived by western snowy 71 plovers as predators. She also found that the general response of roosting western snowy plovers to low-flying aircraft at Ocean Beach, San Francisco, California, was to increase vigilance and crouch in depressions on the beach, whereas foraging western snowy plovers frequently took flight. Plovers may, however, become acclimated to aircraft overflights in some instances, since at Naval Air Station North Island they chose to nest repeatedly within military airfield boundaries on runway ovals next to busy military runways (S. Vissman, U.S. Fish and Wildlife Service, pers. comm. 1997). Federal Aviation Regulations, Part 91, General Operating and Flight Rules, require that over open water, aircraft may not be operated closer than 152 meters (500 feet) to any person, vessel, vehicle, or structure. Emergency operations, including those by Coast Guard helicopters, are exempted from these rules. However, helicopters may be operated at less than 152 meters (500 feet) if the operation is conducted without hazard to people or property on the surface (U.S. Federal Aviation Administration 1997). Helicopters can cause excessive noise, which can also disturb western snowy plovers, even at an altitude of 152 meters (500 feet) (Howard et al. 1993; J. Watkins in litt. 1999; D.

Stadtlander, pers. comm. 1999). At Marine Corps Base Camp Pendleton, California, where military training can require aircraft (especially helicopters) to fly at very low elevations, the Marine Corps minimizes impacts to western snowy plovers and California least terns by requiring aircraft to stay at least 91 meters (300 feet) above the ground over tern and plover nesting areas during the nesting season (U.S. Marine Corps 2006).
x. Special Events
Special events which attract large crowds, such as media events, sporting events, and beach clean-ups, have a potential for significant adverse impacts when held in or near western snowy plover habitat. An example is the National Marine Debris Monitoring Program, implemented by the U.S. Environmental Protection Agency in conjunction with the National Oceanic and Atmospheric Administration, National Park Service, and the U.S. Coast Guard. This year-round program uses volunteers (including high school students) to document and collect trash and marine debris on coastal transects within western snowy plover nesting and wintering habitat.

Potential threats from crowds of people attracted to special events are similar to 72 those previously identified for pedestrians, including direct mortality and harassment of western snowy plovers.
xi. Coastal Access
Expanding public access to the coast (e.g., State Coastal Trails) for recreation (e.g., walking, hiking, biking) may adversely affect western snowy plovers and their breeding or wintering habitat. Expanded coastal access brings significantly greater numbers of people to the beach and other coastal habitats, exacerbating potential conflicts between human recreational activities and western snowy plover habitat needs (see Pedestrian section). Expanded coastal access may exceed the threshold of beach visitors that public resource agencies (e.g., State Parks and National Park Service) can effectively manage while also meeting their responsibilities to protect natural resources.

Bicycles are known to adversely affect western snowy plovers nesting on levees and roads near San Francisco Bay salt ponds within the Don Edwards San Francisco Bay National Wildlife Refuge. Many of these levees are closed to human access, but some bicyclists trespass onto closed levees. In 1998, one western snowy plover nest, located on the main access road to the Refuge, was run over by a bicycle as biologists were putting up a barrier to protect it (J. Albertson in litt. 1999).
xii. Livestock Grazing
Western snowy plover nests have been trampled by cattle, causing both direct mortality of eggs and flushing of adults from the nests (U.S. Fish and Wildlife Service in litt. 1995). Additionally, feral pigs (Sus scrofa) may trample western snowy plover habitat and disturb nesting western snowy plovers (R. Klinger, The Nature Conservancy, pers comm. 1998, D. George in litt. 2001). Cow and horse manure can introduce seeds of non-native plants into the dunes. 73 c. Oil Spills
The Pacific Coast population of the western snowy plover is vulnerable to oil spills.

Western snowy plovers forage along the shoreline and in sea wrack (seaweed and other natural wave-cast organic debris) at the high-tide line and are thus at risk of direct exposure to oil during spills. The loss of thermal insulation is considered to be the primary cause of mortality in oiled birds (National Research Council 1985, Leighton 1991). Oiled feathers lose their ability to keep body heat in and cold water out, causing reduced insulation, increased metabolic rate, and hypothermia.

Ingestion of oil may lead to physiological changes in birds, including pathological effects on the alimentary tract, blood, adrenal glands, kidneys, liver, and other organs (Fry and Lowenstine 1985, Khan and Ryan 1991, Burger and Fry 1993).

Exposure of adult birds to oil also may impair reproduction, including reductions in egg laying and hatchability (Ainley et al. 1981, Fry et al. 1986) and reductions in survival and growth of chicks (Trivelpiece et al. 1984). Oil transferred to eggs from plumage or feet of incubating birds can kill embryos (Albers 1977, Albers and Szaro 1978, King and Lefever 1979). Oiled shorebirds may spend more time preening and less time feeding than unoiled birds, such that their body condition and ability to migrate to breeding grounds and reproduce may be impaired (Evans and Keijl 1993, Burger 1997).

Oil spills may result in contamination or depletion of western snowy plover food sources. Elevated concentrations of total petroleum hydrocarbons have been found in the sand crab (Emerita analoga), a potential western snowy plover food item, following a southern California oil spill (J.E. Dugan, unpublished data). Oil or other chemicals washed onto mudflats or sand beaches may result in reduction in the availability of invertebrate prey (Kindinger 1981). Elimination of shorebird food resources on intertidal flats of the Saudi Arabian Gulf coast as a result of the large oil spills associated with the 1991 Gulf War led to drastic reductions in the number of shorebirds supported by this habitat (Evans et al. 1993). Disturbance and other adverse impacts to western snowy plovers also may occur during oil clean-up activities if response teams are not careful when driving heavy equipment and vehicles or traversing on foot through western snowy plover habitat. 74 During the 1990s, at least six oil spill incidents in California and one in Oregon resulted in adverse impacts to western snowy plovers. The U.S. Coast Guard and various other State and Federal agencies and the responsible parties responded to these spills. One of these incidents occurred between 1984 and 1998 at Unocal’s Guadalupe Oil Field in San Luis Obispo, California contaminated western snowy plover habitat with toxic hydrocarbons. In 1993, oil spilled from a ruptured oil transfer line into McGrath Lake, Ventura County, California and then flowed into the Pacific Ocean. Western snowy plover habitat and prey were contaminated with oil and wintering western snowy plovers were displaced during the cleanup activities (S. Henry in litt. 1998, McGrath Oil Spill Restoration Scoping Document 1995). In 1996, the SS Cape Mohican discharged fuel oil into the San Francisco Drydock Shipyard, California, where it spread throughout the central bay and into the Pacific Ocean, oiling western snowy plovers and their beach habitat (Cape Mohican Trustee Council 2002, Point Reyes Bird Observatory unpublished data).

In 1997, a pipeline extending between an offshore oil platform (Platform Irene) and the mainland ruptured near Pedernales Point, Santa Barbara County, California, oiling western snowy plovers and wrack where western snowy plovers were seen feeding (Applegate 1998, Ford 1998, Lockyer et al. 2002). In 1997 and 1998, large numbers of tarballs became stranded on beaches at Point Reyes National Seashore and resulted in oiling of snowy plovers and their habitat. Subsequent tarball incidents in 2001 and 2002 resulted in identification of the source of the tarballs as the SS Jacob Luckenbach, an oil tanker that sank in 1953 (Carter and Golightly 2003, Point Reyes Bird Observatory unpublished data, Hughes 2003). In 1999, the dredge M/V Stuyvesant spilled fuel oil into the Pacific Ocean off Humboldt Bay, California (U.S. Coast Guard 2001), resulting in oiling of western snowy plovers and their habitat (LeValley et al. 2001).

In February 1999, the freighter New Carissa went aground near the North Jetty of Coos Bay, Oregon, breaking apart and spilling 25,000 to 70,000 or more gallons of oil into coastal water. (U.S. Bureau of Land Management 2001). The incident oiled approximately 52 snowy plovers, representing at least 60 percent of the Oregon wintering population of western snowy plover (Stern et al. 2000). In Washington, the 1988 Nestucca oil spill and the 1991 Tenyo Maru oil spill may also have affected western snowy plovers or their habitats, although impacts are not as well documented as in the above cases (Larsen and Richardson 1990). 75 In addition to catastrophic spills like those described above, chronic oil pollution may affect western snowy plovers. Surveys of beached birds have shown that small-volume, chronic oil pollution is an ongoing source of avian mortality in coastal regions (Burger and Fry 1993). Dead oiled birds and tarballs are found regularly on Pacific coast beaches in the absence of reported oil spills (Roletto et al. 2000). Potential sources of chronic oiling include natural seeps, bilge water pumping, sunken vessels, urban runoff, and small or unreported spills from vessels, tankers, pipelines, and offshore oil platforms. Elevated concentrations of total petroleum hydrocarbons have been found in the sand crab (Emerita analoga), a potential western snowy plover food item, in the vicinity of natural oil seeps (Dugan et al. 1997).

Intensive oil spill cleanup operations, including use of vehicles to deploy beach booms, move personnel, and remove debris, cause disturbance to nesting and foraging activities of western snowy plovers. These temporary impacts are offset by restoration of habitat and cleaning affected birds.
d. Contaminants
The most likely route of exposure of western snowy plovers to contaminants other than spilled oil is through the diet. Western snowy plovers feed on aquatic and terrestrial insects, and the bioaccumulation of environmental contaminants on western snowy plover nesting and wintering grounds may adversely affect their health and reproduction. Organochlorines are known to have caused reduced avian egg production, aberrant incubation behavior, delayed ovulation, embryotoxicosis, and mortality of chicks and adults (Blus 1982). Selenium has caused decreased hatchability of avian eggs, developmental abnormalities, altered nesting behavior, and embryotoxicosis in birds in field and laboratory studies (Ohlendorf et al. 1986, Heintz et al. 1987). Mercury can cause decreased hatchability of avian eggs (Connors et al. 1975), boron has been shown to reduce hatchability of waterfowl eggs in laboratory experiments (Smith and Anders 1989), and arsenic may also adversely affect avian reproduction (Stanley et al. 1994).

Hothem and Powell (2000) analyzed 23 western snowy plover eggs collected from 5 sites (Camp Pendleton Marine Corps Base, Batiquitos Lagoon, Naval Amphibious 76 Base Coronado, Sweetwater Marsh National Wildlife Refuge, and Tijuana Estuary) in southern California from 1994 to 1996 for metals and trace elements, and 20 eggs for organochlorine pesticides and metabolites. All eggs were either abandoned or failed to hatch. Organochlorines, including dieldrin, o,p’-DDD, o,p’- DDE, o,p’-DDT, p,p’-DDD, p,p’-DDE, p,p’-DDT, oxychlordane, and trans- nonachlor were found above the detection limits in western snowy plover eggs.

Median DDE and PCB concentrations were less than those normally associated with eggshell thinning. deformities, or other detrimental effects on birds. Twelve metals and trace elements (arsenic, boron, chromium, copper, iron, magnesium, manganese, mercury, nickel, selenium, strontium and zinc) were detected in at least 90 percent of the samples, but generally at background levels. Mean concentrations of all contaminants were below those that would adversely affect reproduction.

Concentrations of mercury in western snowy plover eggs that failed to hatch at Point Reyes National Seashore were five to ten times higher than the mercury concentrations in the five Southern California locations studied by Hothem and Powell (Schwarzbach et al. 2003). The mean mercury concentration of 1.07 micrograms/gram (1.07 parts per million), wet weight, in western snowy plover eggs from Point Reyes National Seashore is probably high enough to account for egg failure through direct toxic effects to western snowy plover embryos (Schwarzbach et al. 2003). Because only failed and abandoned eggs were taken rather than randomly collected eggs, the extent of mercury contamination of the entire breeding western snowy plover population at Point Reyes can not be reliably assessed from these data; however, the data from the 2000 field season would suggest that about one fifth of the nests appeared to be at risk from adverse effects of mercury (Schwarzbach et al. 2003).
e. Litter, Garbage, and Debris
Placement of litter, garbage, and debris in the coastal ecosystem can result in direct harm to western snowy plovers and degradation of their habitats. Litter and garbage feed predators and encourage their habitation at higher levels than would otherwise occur along the coast, making predators a greater threat to western snowy plovers. For example, as noted previously, the California gull (Larus californicus) has become far more prevalent in the South San Francisco Bay area. Currently, the 77 estimated 25,000 California gulls in this area feed in landfills and forage in salt marshes using habitat that once supported the western snowy plover (J. Albertson, pers. comm. 2005).

Marine debris and contaminated materials on the beach also adversely affect western snowy plovers. Marine debris is attributed to both ocean and shoreline sources. Ocean sources of marine debris and contamination include fishing boats, ships, and cruise lines. Cruise line debris may include small plastic shampoo, conditioner, hand lotion, and shoe polish containers, plastic cups, and balloons (Center for Marine Conservation 1995). Shoreline debris is usually from land sources. Western snowy plovers may become entangled in discarded fishing line, fishing nets, plastic rings that hold together six-packs of canned drinks, and other materials on the beach. Containers of contaminated materials (e.g., motor oil, cleaning fluid, and syringes) can introduce toxic chemicals to the beach. The National Marine Debris Monitoring Program, headed by the U.S. Environmental Protection Agency, was established to clean and track sources of marine debris in coastal areas. This monitoring program, while beneficial to western snowy plovers in the long-term, could potentially adversely affect nesting western snowy plovers since the program is conducted year-round. Similarly, the annual spring SOLV beach cleanup held on the Oregon Coast in late March and the annual Coastal Cleanup Day held on the California coast in September are two organized beach events that are poorly timed with respect to prospecting and nesting western snowy plovers. These programs could greatly improve western snowy plover habitat if timed appropriately.
f. Water Quality and Urban Run-off
Many coastal beaches used as habitat by western snowy plovers contain channelized streams or outfalls receiving run-off from urban, industrial, and agricultural areas. Nonpoint sources of water pollution (including hydrocarbons, heavy metals, and household chemicals) could end up at coastal beaches used as western snowy plover foraging areas. In 1995, three dead male western snowy plovers (all banded and local breeders) were found in an area containing local outfalls, including an outfall connected to a sewage treatment plant at Monterey Bay. By the beginning of the next breeding season, it was discovered that another 78 male western snowy plover from this area disappeared and possibly died. Factors unrelated to the outfall have not been ruled out in the disappearance of this bird.

One of the birds was analyzed through necropsy and found to have an enlarged liver, but it could not be determined whether there was a relationship between the mortality and the outfall (Point Reyes Bird Observatory unpublished data). g. Management for Other Special Status Species
In several instances fencing used to enclose California least tern colonies has caused mortality of western snowy plover chicks that have become entangled within the fence mesh (Powell and Collier 1995, Powell et al. 1995), or prevented western snowy plover chicks from following their parents to feeding areas by blocking their movement (Powell et al. 1996). These issues have largely been resolved by utilizing fencing with a mesh size of less than 0.64 centimeter (0.25 inch), tightening gaps in fencing seams, and installing “gates” in tern fencing (Foster 2005). Monitoring and minimization measures to avoid these impacts continue to be implemented in coordination with the appropriate Fish and Wildlife Offices. Increasing density and abundance of California least terns within colonies may also result in western snowy plovers being displaced a short distance, but the benefits of tern management for western snowy plovers appear to outweigh such conflicts.

At the Channel Islands and other lands managed by the National Park Service and the Department of the Navy, a decline of western snowy plovers may be caused by disturbance and habitat loss resulting from the large increase in numbers of marine mammals on beaches (U.S. Fish and Wildlife Service in litt. 1995, U.S. Department of the Navy in litt. 2001). Breeding pinnipeds, including northern elephant seals (Mirounga angustirostris), northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus) at San Miguel Island and San Nicolas Island, have occupied western snowy plover nesting habitat. Beach-cast dead whales have, on occasion, posed threats to nesting western snowy plovers. At Point Reyes beaches, large, whole carcasses have washed ashore and other agencies such as the National Marine Fisheries Service have sought to collect them for scientific purposes. They also attract people who are curious about whales. These activities 79 could potentially cause direct mortality and disturbance to western snowy plovers.

In addition, mammal carcasses attract scavengers such as gulls, ravens, crows, and coyotes that are potential predators to western snowy plovers.

E. IMPLICATIONS FOR THE COASTAL BEACH-DUNE ECOSYSTEM
The western snowy plover lives in an ecosystem that has been significantly degraded. Environmental stressors (i.e., development, human recreation, degraded water quality, etc.) have adversely affected the biological diversity of the coastal dune ecosystem. Many of the characteristics that attract people to coastal areas make these areas prime habitat for fish and wildlife resources. Although they comprise less than 10 percent of the Nation, coastal ecosystems are home to over one-third of the United States human population, nearly two-thirds of the Nation’s fisheries, half of the migratory songbirds, and one-third of our wetlands and wintering waterfowl (U.S. Fish and Wildlife Service 1995a). The coasts also provide habitat for 45 percent of all threatened and endangered species, including three-fourths of the federally-listed birds and mammals (U.S. Fish and Wildlife Service 1995a). Proper stewardship of this unique ecosystem is needed to maintain its ecological integrity while meeting its human demands.

1. Description of Coastal Beach-Dune Ecosystem
The coastal beach-dune ecosystem may include several features such as beaches, foredunes, deflation plains, blow-outs, and reardunes. The beach includes the expanse of sandy substrate between the tide line and the foredune or, in the absence of a foredune, to the furthest inland reach of storm waves. Beach steepness, height, and width are affected by wave height, tidal range, sand grain size, and sand supply.

The beach has high exposure to salt spray and sand blast and contains a shifting, sandy substrate with low water-holding capacity and low organic matter content.

Dunes include sandy, open habitat, extending from the foredune to typically inland vegetation on stabilized substrate. Major differences occur between beach and dune in salt spray, soil salinity, and air and soil temperatures (Barbour and Major 1990).
80 Coastal dunes generally consist of three primary zones (Powell 1981). The foredunes are the line of dunes paralleling the beach behind the high tide line.

Foredunes are characterized by unstabilized sand and a simple community of low- growing native dune plant species, such as American dunegrass (Leymus mollis).

Foredunes also support a rich community of sand-burrowing insects (Powell 1981).

Behind the foredunes is the deflation plain, which is at or near the water table and is characterized by a mixture of water tolerant plants and dune species. Deflation plains are also called dune hollows and can be invaded by hydrophilic (having a strong affinity for water) trees, shrubs, or herbs (e.g., species of Carex, Juncus, Salix, Scirpus) (Barbour and Major 1990). The inner zone of coastal dunes consists of stabilized dunes, which are dominated by woody perennial plants (Powell 1981).

Beach flora can also colonize inland dune areas, where the sand is actively moving (Barbour and Major 1990).

Barren dunes, receiving sand from the beach and losing it to wind erosion, are mobile. Older, more inland dunes are stabilized by a nearly continuous plant cover; these dunes are referred to as stable dunes or fixed dunes. Localized openings in the plant cover, which permit wind erosion, are called blowouts, but they are not deep enough to allow invasion by mesophytes (plants growing in moderately moist environments). The innermost ridge of sand is generally high and is called a precipitation ridge; sand is blown over the ridge and down the slipface, continuing the process of dune advance (Barbour and Major 1990). The conditions necessary for dune growth at the coast are partly climatic, but more important is the occurrence of strong onshore winds, abundant sand supply, and vegetation that traps sand. Low, near-shore slopes with a large tidal range providing wide expanses of sand that dries at low tide are ideal for dune growth (Pethick 1984).

Very few coastal dunes are “natural,” because they have been extensively altered over time by humans for agriculture, mineral extraction, military training, and recreation (Carter 1988). Before the introduction of European beachgrass, foredunes were low and rose gradually, and a large number of native species shared this habitat. They were composed of a series of dunes alternating with swales oriented perpendicular to the coast and aligned with prevailing onshore winds.

Since the introduction of European beachgrass, most systems have been replaced by 81 a steep foredune that gives way inland to a series of dunes and swales oriented parallel to the coast (Barbour and Major 1990).

Western snowy plovers use the beach and mobile dunes as nesting habitat. Other habitat features that occur within or adjacent to the coastal beach-dune ecosystem, and serve as important foraging habitat for the western snowy plover, include river, stream, and creek mouths, river bars, lagoons, and tidal and brackish-water wetlands.

2. Sensitive Species of the Coastal Beach-Dune Ecosystem Along with the western snowy plover, many other sensitive species inhabit the coastal beach-dune ecosystem and adjacent habitats. Appendix E contains a list of, and brief species accounts for, sensitive species associated with this ecosystem and adjacent habitats. We recognize these fish and wildlife species as endangered, threatened, candidate species, or species of concern. This list includes a number of sensitive species recognized by the states of California, Oregon, and Washington.

This appendix also describes several marine mammals associated with the coastal beach-dune ecosystem and protected under the Marine Mammal Protection Act of 1972 (16 U.S.C. 1361 et. seq.), as amended.

Some of these sensitive species have many threats in common with the western snowy plover. Habitat loss and degradation from shoreline development and beach stabilization, invasion of exotic species, and crushing by off-road vehicles are cited as major factors contributing to the status and listing of these species. European beachgrass is a current or potential threat to six federally-listed endangered plants that occur in coastal dunes of California: beach layia (Layia carnosa), Howell’s spineflower (Chorizanthe howellii), Monterey spineflower (Chorizanthe pungens var. pungens), Menzies’ wallflower (Erysimum menziesii), Monterey gilia (Gilia tenuiflora ssp. arenaria), and Tidestrom’s lupine (Lupinus tidestromii) (Pickart 1997). European beachgrass is also a current and potential threat to native and sensitive plants in Washington and Oregon, including the pink sand-verbena (Abronia umbellata ssp. breviflora), which is classified as endangered in the State 82 of Oregon. Equestrian use has also been identified as a threat to several endangered plant species, including the endangered Howell’s spineflower, Menzies’ wallflower, Monterey gilia, and the coastal dunes milk vetch (Astragalus tener var. titi). Off- road vehicles are cited as threats to several sensitive plant and animal species, including the endangered beach layia, Menzies’ wallflower, Monterey gilia, Tidestrom’s lupine, Hoffman’s slender-flowered gilia (Gilia tenuiflora var. hoffmanii), and Smith’s blue butterfly (Euphilotes enoptes smithi); the federally endangered La Graciosa thistle (Cirsium longholepis), and the following species considered to be of Federal concern: beach spectacle pod (Dithyrea maritima) and Morro blue butterfly (Icaricia icarioides morroensis).

The precarious status of these species is a symptom of a highly stressed ecosystem.

Remedial efforts aimed at restoration of the natural processes that maintain this ecosystem, rather than single-species “fixes,” are likely to have the greatest and most successful long-term benefits. Important components of ecologically-sound coastal beach-dune ecosystem management include (1) removal of exotic, invasive vegetation; (2) management of human recreation to prevent or minimize adverse impacts on dune formation, vegetation, invertebrate and vertebrate fauna; and (3) efforts to counter the effects of human-induced changes in the types, distribution, numbers, and activity patterns of predators. Implementation of more ecosystem- oriented approaches to western snowy plover protection would provide important benefits to other sensitive species within the coastal dune ecosystem and merits serious consideration.

Some western snowy plover recovery efforts implemented to date (e.g., removal of European beachgrass) support the natural functions of the coastal dune ecosystem.

Furthermore, many protection efforts for western snowy plovers should benefit other sensitive beach species, such as California least terns, and vice versa. Many of the same predators that take western snowy plover eggs also prey on California least tern eggs. The relatively low rate of predation of western snowy plover nests in San Diego County has been attributed to predator control programs to benefit California least terns and other species, funded primarily by the Department of Defense and National Wildlife Refuge System (Powell et al. 1995). These programs are implemented under contract with the U.S. Department of Agriculture, Wildlife Services branch. Control of ants at California least tern colonies probably 83 also benefits western snowy plovers nesting nearby. Opportunities also may exist for reestablishment of special status plant species that occur in coastal dunes, including Menzies’ wallflower, beach spectacle pod, Tidestrom’s lupine, beach layia, and pink sand verbena.

Some conflicts have occurred in management of western snowy plovers and California least terns in southern California, including harm to western snowy plover chicks due to entanglement in the mesh of California least tern fencing as described above. These problems have now largely been minimized with the use of new methods and materials, however such management measures should continue to be coordinated to meet the habitat needs of both western snowy plovers and California least terns.

Potential conflicts also exist between native dune restoration and western snowy plover habitat. Revegetation efforts could result in too much cover, thereby reducing the amount of suitable breeding habitat available for western snowy plovers.

Conflicting habitat requirements for western snowy plovers and pinnipeds have also occurred on lands where marine mammals haul out or breed on beaches that would otherwise be suitable for nesting western snowy plovers (U.S. Fish and Wildlife Service in litt. 1995, U.S. Department of the Navy in litt. 2001). Where this conflict continues to occur, coordination with land management agencies and NOAA’s National Marine Fisheries (NMFS) may be helpful to identify methods for modifying or discouraging use by breeding pinnipeds during the western snowy plover nesting season.

Although some management measures may benefit a broad array of sensitive species within the coastal dune ecosystem (i.e., control of Ammophila, access restrictions, and integrated predator management programs), some single-species protection measures for the western snowy plover, such as exclosures, are needed.

Although exclosures can be risky to nesting western snowy plovers in some situations (see Lauten et al. 2006), they can be an effective way to protect nests against heavy recreational use and predation, especially where reductions in 84 predator numbers would otherwise be temporary and difficult to achieve or would have adverse ecological effects.

F. CONSERVATION EFFORTS
Western snowy plover recovery efforts have accelerated since this population was federally listed as a threatened species in 1993. Current breeding and wintering site protection efforts are documented in Appendix C (Summary of Current and Additional Needed Management Activities). The most common management strategies include protection of nests with predator exclosures; signing and symbolic fencing of nesting areas; restrictions on motorized vehicles in the vicinity of western snowy plover nests and broods; restrictions on dogs (even though enforcement of dogs on-leash has been problematic); and public information and outreach. These strategies are effective means of improving western snowy plover reproductive success.

1. Conservation Planning on Federal and State Lands
The direction of land management on Federal lands is often outlined in management plans or agency regulations that provide objectives and guidelines for western snowy plovers. These plans include the Naval Base Coronado Integrated Natural Resources Management Plan (U.S. Navy 2001), Camp Pendleton Integrated Natural Resources Management Plan (U.S. Marine Corps 2006), San Diego Bay National Wildlife Refuge Comprehensive Conservation Plan (U.S. Fish and Wildlife Service 2006c), Oregon Dunes National Recreation Area Management Plan (U.S. Forest Service 1994), the Coos Bay Shorelands Final Management Plan (U.S. Bureau of Land Management 1995a), the New River Area of Critical Concern Management Plan (U.S. Bureau of Land Management 1995b), the Draft Snowy Plover Management Plan for Ocean Beach, Golden Gate National Recreation Area (Hatch 1997), and the Western Snowy Plover Management Plan for the Point Reyes National Seashore (White and Allen 1999).

Wildlife protection, especially the preservation, restoration, and enhancement of threatened and endangered species and migratory birds, is the primary goal of national wildlife refuges, as stated in the National Wildlife Refuge System 85 Administration Act of 1997 (16 U.S.C. 668dd et. seq.). Western snowy plover habitat on national wildlife refuges has been accorded intensive protection, including (1) integrated predator management and (2) closures during the nesting season where appropriate, to minimize adverse effects of disturbance. Consistent with requirements of the National Wildlife Refuge System Administration Act and the Refuge Recreation Act of 1962, as amended (16 U.S.C. 460k et. seq.) regarding compatibility of refuge activities, western snowy plover nesting areas within some national wildlife refuges are closed to public use during the breeding season.

Western snowy plover use areas within some national wildlife refuges (such as Salinas River National Wildlife Refuge) are closed to public use year-round.

Additionally, the Department of Defense manages for western snowy plovers on military installations through actions associated with section 7 of the Endangered Species Act and through conservation planning efforts (e.g., Programmatic Activities and Conservation Plans in Riparian and Estuarine/Beach Ecosystems on Marine Corps Base Camp Pendleton, 1995; see also Federal Regulatory Program, below). This includes avoidance and minimization measures, which have resulted in individual military installations placing limits on or otherwise restricting military activities and implementing management actions to specifically benefit western snowy plovers, such as monitoring, predator control, habitat improvement, and research. This management, in conjunction with other factors such as habitat availability and restricted public access, has allowed certain Department of Defense lands to significantly contribute to regional western snowy plover populations.

The Washington State Recovery Plan for the Western Snowy Plover recommends strategies to recover this species, including protection of the population, evaluation, and management of habitat, and initiation of research and education programs (Washington Department of Fish and Wildlife 1995).

The State of Oregon’s Conservation Program for the Coastal Population of the Western Snowy Plover, required by the Oregon Endangered Species Act and adopted by the Oregon Fish and Wildlife Commission (Oregon Revised Statutes 496.171 through 496.192), requires a variety of actions to protect this subspecies.

These actions include: (a) protecting all existing western snowy plover sites from negative impacts; (b) monitoring impacts and responding to damaging activities 86 (e.g., urban development and recreation disturbance) to minimize or eliminate their effects to western snowy plovers; (c) maintaining a long-term monitoring program to track numbers, distribution, and nesting success; (d) habitat management, such as local control of European beachgrass and maintaining predator protection measures to maximize breeding success for as long as deemed necessary; (e) conducting additional research to maintain and recover western snowy plovers; and (f) enhancing information availability, education, and awareness of western snowy plovers and their requirements for survival and recovery (Oregon Department of Fish and Wildlife 1994).

The California Public Resources Code (Section 5019.71) allows designation of natural preserves, the most protective designation given to a part of any California State Park system unit. The purpose of natural preserves is to preserve such features as rare or endangered plant and animal species and their supporting ecosystems, and representative examples of plant or animal communities existing in California prior to the impact of civilization. The Pajaro Rivermouth Natural Preserve, Wilder Creek Natural Preserve, and Salinas Rivermouth Natural Preserve were designated by the California State Park and Recreation Commission in recognition of the need to protect western snowy plovers. In addition, Section 5019.62 of the California Resources Code allows the designation of State seashores to preserve the outstanding values of the California coastline and provide for public enjoyment of those values. Within the state of California, the following California State seashores containing western snowy plover habitats have been established:

Del Norte State Seashore; Clem Miller State Seashore; Sonoma Coast State Seashore; Año Nuevo State Seashore; Monterey Bay State Seashore; San Luis Obispo State Seashore; Point Mugu State Seashore; Capistrano Coast State Seashore; and San Diego Coast State Seashore. Under the California Public Resources Code, the California Department of Parks and Recreation has the authority to identify additional lands appropriate for inclusion in California State seashores and recommend land acquisition for these purposes.

Special management actions for western snowy plovers are conducted within the portions of California State Seashores that are owned by the California Department of Parks and Recreation. An example is the Monterey State Seashore, where the California Department of Parks and Recreation has conducted intensive 87 management activities for western snowy plovers since 1991. Strategies include resource management, interpretation, law enforcement, and park operations.

Resource management actions include monitoring, predator trapping, and use of exclosures, symbolic fences, and signage, and consideration of snowy plovers during planning recreational access and trails in San Francisco Bay. Interpretative efforts include informational signage at nesting areas, information brochures, small handout cards with photographs and information on western snowy plovers, several annual public outreach programs (e.g., slide programs and field trips), and actions to engage community support for the western snowy plover guardian program (i.e., recruitment, training, and scheduling for volunteer presence in sensitive habitat).

Enforcement actions include verbal warnings, written warnings, citations, and arrests as necessary. Key enforcement concerns include dogs off-leash and off-road vehicles, which are prohibited on all beaches. Operational management includes a permit process that screens special events to avoid the nesting season in sensitive areas, and regulation of recreational use of beaches to avoid sensitive areas (i.e., kite flying, hang gliding, fishing, etc.). Other management actions on California Department of Parks and Recreation property within some other State seashores are shown in Appendix C.

2. Conservation Efforts on Federal and State Lands
a. Exclosures, Symbolic Fencing, and Signs
Since 1991, one of the primary techniques to protect nesting western snowy plovers has been the use of exclosures (Appendix F). Exclosures are small, circular, square, or triangular metal fences that can be quickly assembled and are designed to keep predators out of nests and/or prevent people from trampling nests (Figure 8).

Exclosure designs are described in Appendix F; modifications to exclosure design in response to site specific predator conditions may be appropriate on a case by case basis but should be coordinated in advance with the Fish and Wildlife Service.

Nests protected from predators by exclosures have consistently had increased nest success (White and Hickey 1997, Stern et al. 1991, Craig et al. 1992, Mabee and Estelle 2000, U.S. Fish and Wildlife Service 2002, Lauten et al. 2006). At some locations in Oregon and California, exclosures are designed with tops consisting of 88 parallel lengths of nylon seine lines spaced approximately 15 centimeters (6 inches) apart -or- mesh netting with a minimum spacing of approximately 10 centimeters (4 inches), designed to discourage entry by avian predators. At Eden Landing State Ecological Reserve in San Francisco Bay, nest predation decreased from 32 percent in 2000 to 3 percent in 2001, largely due to a switch from string tops to net tops on exclosures (Marriott 2001).

Figure 8. Erecting western snowy plover exclosure (photo by Sue Powell, with permission).

Although exclosures are contributing to improved productivity and population increases in some portions of the western snowy plover’s Pacific coast range, problems have been noted in some localities. Potential risks associated with exclosures include vandalism, disturbance of the birds by curiosity seekers, and use of exclosures as predator perches. Over time, exclosures may provide a visual cue to predators, making it easier for them to target adults, chicks, and eggs, and requiring predator management. On several occasions depredations of adult western snowy plovers have been documented in or near exclosures, and efforts have been made to establish exclosures later in the season after the peak migration 89 of raptors (Brennan and Fernandez 2004, Lauten et al. 2006). Also, predator exclosures may be impractical where western snowy plovers nest within California least tern colonies or other instances where such exclosures may conflict with the needs of other threatened or endangered species.

Symbolic fencing also is used to passively protect western snowy plover nests, eggs, and chicks during nesting season. This fencing consists of one or two strands of light-weight cord or cable strung between posts to delineate areas where humans (e.g., pedestrians and vehicles) should not enter (Figure 9). It is placed around areas where there are nests or unfledged chicks, and is intended to prevent accidental crushing of eggs, flushing of incubating adults, and, if large enough, to pro vid
e an
are a
wh ere
chi cks
can rest
and see
k she
lter wh
en lar
ge nu
mb ers
of peo
ple are
on the
beach. Directional signs (regarding closed areas, nesting sites, etc.) also are used within western snowy plover habitats and near protective fencing to alert the public and other beach users of the sensitivity of western snowy plover nesting and wintering areas. Installation of symbolic fencing at Coal Oil Point Reserve (CA- 88) in conjunction with a docent program has allowed management of 90 Figure 9. Symbolic fencing on beach at Monterey Bay, California (photo by Ruth Pratt, with permission).
recreational use and resulted in successful re-establishment of a breeding population of western snowy plovers at the site (Lafferty et al. 2006).

Additionally, land managers may prevent or restrict access to areas used by nesting western snowy plovers. For example, military installations often curtail or redirect training activities near western snowy plover nesting areas and some State parklands and recreation areas restrict public access in certain areas during the breeding season.
b. Law Enforcement
Management agencies recognize that law enforcement is needed for protection measures to be effective. Though a majority of beach visitors respect restrictions to protect western snowy plovers, there will always be a certain percentage who do not. Enforcement of western snowy plover area restrictions shows that managers are serious about compliance. In Oregon, biologists have established a working relationship with a variety of law enforcement agencies who have jurisdiction in western snowy plover habitat. Their goal is to increase awareness, gain advice, increase communication and coordination to alleviate jurisdictional conflicts, and train officers on how to minimize disturbance while patrolling western snowy 91 plover habitat. Conflicting priorities and personnel turnover require perseverance to maintain effective working relationships across law enforcement jurisdictions. c. Predator Control
Lethal and nonlethal means of predator control have been used with mixed success to protect western snowy plovers on Pacific beaches. Nonlethal methods include litter control at campgrounds (to reduce available food sources), exclosures and fencing, and trapping and relocation. Lethal methods include reducing local populations of avian predators by addling (i.e. killing the developing chick within the egg) of raptor and corvid eggs, trapping and euthanizing nonnative mammalian predators, and killing individual predators upon which nonlethal methods have proven ineffective.

On the Oregon Coast, snowy plover predator control has historically been in the form of nest exclosures and site specific lethal control. The use of nest exclosures, adaptively modified in response to predator behavior, has been very successful in increasing hatching success. However, because in some cases predation on adults has been linked to the presence of exclosures, their use is presently targeted to specific instances where it appears most beneficial, and the program is working toward elimination of exclosure use (Lauten et al. 2006a, 2006b).

In 2002, Federal and State agencies approved an integrated predator management program to improve western snowy plover nesting and fledging success in Oregon.

The decision followed public review and comment on an analysis of the effects of the proposed predator control methods and alternatives to protect the western snowy plover in Oregon (U.S. Department of Agriculture 2002). To date lethal predator control has been implemented at selected plover breeding sites along the Oregon Coast at Coos Bay North Spit, Bandon Beach, New River, Siltcoos, Overlook, Tahkenitch, and Tenmile, resulting in an overall positive effect on western snowy plover productivity (Lauten et al. 2006a, 2006b).

Another form of predator control is fencing, which is used on the south spoils area of Coos Bay, North Spit, where the U.S. Bureau of Land Management, U.S. Army Corps of Engineers, and Oregon Department of Fish and Wildlife have fenced 8 92 hectares (20 acres) of western snowy plover nesting habitat. This wire mesh fence was installed to exclude mammalian predators, especially skunks, and to discourage human disturbance from off-highway vehicle use. The original fence, constructed in 1991, suffered from the effects of weathering and although it continued to deter vehicles, it was no longer an effective barrier to predators. In 1998, the U.S. Army Corps of Engineers and U.S. Bureau of Land Management jointly constructed a new fence and removed the old fence. The new fence matched the design of the 1991 fence (5-centimeter by 5-centimeter (2-inch by 2-inch) mesh fence material with an effective fence height of about 1.2 meters (4 feet) after burial of the bottom).

However, the new fence has increased the protected area from 8 hectares (20 acres) to 28 hectares (71 acres), and includes both the south spoils area and the 1994 Habitat Restoration Area (E.Y. Zielinski and R.W. Williams in litt. 1999).

At the Don Edwards San Francisco Bay National Wildlife Refuge, fences are sometimes constructed across salt pond levees to block access by terrestrial predators (J. Albertson in litt. 1999). However, fences are not feasible in many areas, and do not restrict aerial predators.

Exclosures are much more effective when used in conjunction with an integrated predator management program that includes selective removal of non-native predators and other individual problem predators. Otherwise, exclosures may promote better hatching success, but not fledging success if predators such as red fox (Vulpes vulpes) focus on adults protecting the nest or newly-hatched chicks that leave the exclosure to feed. These measures are also much more effective where combined with other access restrictions to increase survival of clutches and broods.

Trapping the nonnative red fox has been credited with substantially increased western snowy plover abundance and productivity at Salinas River National Wildlife Refuge (E. Fernandez, U.S. Fish and Wildlife Service, pers. comm. 1998). At the Don Edwards San Francisco Bay National Wildlife Refuge, predation on western snowy plovers and California clapper rails by red foxes prompted the initiation of a predator management program targeting red foxes, feral cats, skunks, and raccoons, in conjunction with use of western snowy plover nest exclosures (J. Albertson in litt. 1999, Strong et al. 2004). This ongoing program has resulted in improved nest success. Use of exclosures has subsequently been discontinued due to the success of the trapping program and incidents of nest abandonment at exclosures. At Eden 93 Landing Ecological Reserve selective removal of problem corvids and their nests has also been practiced by USDA Wildlife Services since 2004 (Tucci et al. 2006).

The U.S. Air Force has used electric fencing around the California least tern colony at Purisima Point, Vandenberg Air Force Base, California, where western snowy plovers also nest and winter. The electrified portion of this fence is approximately 273 meters (300 yards) long and 1.2 meters (4 feet) high. The electric fence contains six strands of electrified wire placed approximately 10.2 centimeters (4 inches) apart. This fence is generally effective at keeping out mammalian predators of California least terns. It has also incidentally protected a small population of western snowy plovers by deterring western snowy plover predators.

Proposals have been developed to test a conditioned taste aversion technique on predators of piping plovers (i.e., red fox) by using quail eggs treated with the chemical emetine (McIvor 1991). The purpose of this technique is to condition foxes to avoid eating plover eggs, expecting that if foxes eat treated quail eggs prior to the nesting season and become sick, they might develop a conditioned aversion to eating plover eggs. This technique requires that the predator consumes the needed dose that will produce short-term illness but no mortality. Due to uncertainty in effectiveness, at this point in time we do not advocate this taste aversion technique.

Proposals to test conditioned taste aversion techniques on predators of piping plovers on the east coast have not been implemented due to difficulties obtaining permission to field test emetine (A. Hecht, U.S. Fish and Wildlife Service, pers. comm. 1996). Avery et al. (1995) found that deployment of quail eggs treated with the chemical methiocarb might be a useful means of reducing predation of California least terns by ravens and crows. However, subsequent tests of aversion methods have proven to be unsuccessful (E. Copper and B. Foster in litt. 2001).

With proper research, techniques that have been used to deter predators of other wildlife species may prove beneficial to western snowy plovers. Strategic placement of crow and gull carcasses around the perimeter of a California least tern colony has been used at Vandenberg Air Force Base (Persons and Applegate 1996), however, this method may not be effective for more loosely colonial species such as snowy plover (J. Buffa in litt. 2004). Moreover, the presence of gull carcasses could prove 94 counterproductive by attracting mammalian predators (N. Read, U.S. Air Force, pers. comm. 1998).

In 1999 Vandenberg Air Force Base initiated studies of coyote ecology and movements, with the goal of developing non-lethal alternatives for reducing coyote predation on western snowy plover. Although results are preliminary, in 2001 beach access restrictions and regular pick-up of trash, in combination with availability of alternative prey such as rabbits, may have contributed to the lowest incidence of coyote predation ever recorded at Vandenberg Air Force Base, even though evidence of coyote presence continued to be observed on a daily basis.

For top-level predators such as coyotes, western snowy plover nests are not a primary food source. Vandenberg Air Force Base has avoided large-scale coyote removal to prevent exacerbated predation on listed species from mesopredators such as racoons, and to prevent expansion of non-native predators such as feral cats and red foxes into western snowy plover nesting areas (N. Read Francine in litt. 2001). d. European Beachgrass Control

Experiments to find cost-effective methods to control or eradicate European beachgrass are ongoing. Control methods employed in various situations have included foredune grading and foredune breaching with front-end loaders and bulldozers, subsoiling with a winged subsoiler (essentially a heavy duty three-point plow), discing with a standard farm tractor and disk, burning, saltwater irrigation, spraying of herbicide, and hand-pulling. Herbicide treatment is not always possible, however, when rare or federally-listed plants are present. In these cases hand-pulling or other mechanical removal may need to be employed. At Point Reyes National Seashore mechanical and hand-removal were used to remove non-native beach grass on 12 hectares (30 acres) with immediate beneficial response by nesting snowy plovers (Peterlein and Roth 2003). Some control methods are only suitable for the inland sites. Areas containing heavy growth of European beachgrass and woody vegetation are prescribed-burned prior to using heavy equipment. Areas are leveled to allow discing for maintenance. In some areas, oyster shell hash provided by a local oyster grower has been distributed after vegetation has been removed.

Effectiveness of the various control methods varies, though some form of 95 maintenance may always be required. Maintenance is critical and achieved through multiple treatments over a succession of years. Discing requires maintenance twice per year to keep beachgrass from reestablishing. Comparatively, yearly maintenance in portions of some restoration sites may not be needed after employing several years of bull-dozing, herbicides, or hand-pulling following initial mechanical removal.

Since 1994, multiple projects have been conducted in Oregon to control beachgrass on existing nest sites and to clear and maintain additional areas. These Habitat Restoration Areas (HRAs) are essential for the recovery of the western snowy plover. Three significant HRAs established on the Oregon Coast between 1994 and 2002 include the Dunes Overlook (Oregon Dunes National Recreation Area), Coos Bay North Spit, and New River. Other habitat restoration areas have recently been established or are planned at Baker Beach (140 acres), Tenmile Creek (200 acres) and Bandon Beach State Natural Area (30 acres). HRAs accounted for 34 percent of nests (Table 6) and 43 percent of fledglings (Table 7) found on the Oregon Coast between 1999 and 2004.

The Oregon Dunes National Recreation Area contains about 2,428 hectares (6,000 acres) of European beach grass and now has few remaining examples of intact native plant communities (Pickart 1997). Habitat restoration was initiated in the summer of 1998 and by 2002, the U.S. Forest Service had treated 24 hectares (60 acres) of the 208 hectares (516 acres) of habitat planned for restoration. Prior to 1999, no western snowy plovers were found at the Overlook site, but after habitat was restored, western snowy plovers began nesting there successfully (Table 6, Table 7).

The U.S. Forest Service employs a combination of mechanical, manual, and herbicide treatments to control European beachgrass. Mechanical treatment consists of scalping off the top 1 meter (3 feet) of beachgrass and then burying it in an adjacent trench with a minimum covering of l meter (3 feet) of sand. Moderate to heavy resprouting occurs with this method, requiring manual or chemical follow-up treatment. Other mechanical treatments have consisted of placement of dredged material on the beachgrass and scalping the top half of foredunes to remove beachgrass and allow for inland sand movement and tidal action to maintain open dunes (K. Palermo in litt. 1998b).
96 Herbicide treatments have been conducted as a primary control method and as follow-up to mechanical control. In recent years, from 2 to 26 hectares (5 to 65 acres) of beachgrass were sprayed with an herbicide treatment of 8 percent Rodeo and nonionic surfactant (spray-to-wet) at three locations. Employees found that a follow-up application within 2 weeks of the first application was critical to obtain optimum coverage and initial die-off rates (90 percent). Additionally, herbicide treatments were most effective when conducted consecutively over 2 to 3 years depending on density. Beachgrass control at the Oregon Dunes is still considered experimental. Preliminary results suggest that maintenance will always be necessary (K. Palermo in litt. 1998b).
97 Table 6. Total number of nests at habitat restoration areas on the Oregon Coast 1994-2004 (J. Heaney, pers. comm. 2003; C. Burns, pers. comm.; M. VanderHeyden, pers. comm.; Castelein et. al. 2002; Lauten et al. 2006).

Site Name 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Total Nests
Baker
Beach
0 1 0 1
Dunes
Overlook
2 8 15 8 9 14 56
Coos Bay
North Sp it
4 3 2 3 7 12 22 13 15 11 16 108
Bandon
Stat e NRA
4 17 21
New River 2 4 10 7 5 6 34
Table 7. Total number of fledged young at habitat restoration areas on the Oregon Coast 1994-2004. Includes fledglings from broods from undiscovered nests (J.

Heaney, pers. comm. 2003; C. Burns, pers. comm; M. VanderHeyden pers. comm.; Castelein et. al. 2002; Lauten et al. 2006).

Site Name 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Total Nests
Baker
Beach
0 0 0 0
Dunes
Overlook
3 5 2 2 3 6 21
Coos Bay
North Sp it
7 2 1 1 1 23 6 6 8 14 22 91
Bandon
Stat e NRA
4 15 19
New River 2 1 3 3 7 5 21
98 On Coos Bay North Spit, the Bureau of Land Management has cleared and maintained approximately 67 hectares (166 acres) of vegetation dominated by European beachgrass, shore pine, Sitka spruce, and Scotch broom. The objective is to remove predator cover, remove encroaching beachgrass, and expand the existing habitat. The goal is to create an area for western snowy plovers to nest that is large enough to lessen possible detection of nests and chicks by predators. Nest sites used by western snowy plovers on the North Spit include both beach habitat and inland areas of previous dredged material deposition. Many of the cleared areas were used almost immediately by nesting western snowy plovers or for brood rearing activities.

Prior to 1994, western snowy plovers were not nesting in these areas, but after 1994, the Coos Bay North Spit became the most productive western snowy plover nesting sites on the Oregon Coast (Table 6, Table 7) (M. VanderHeyden, Bureau of Land Management, pers. comm.).

At the Coos Bay North Spit, an inmate crew from the Shutter Correctional Facility, hired by the U.S. Bureau of Land Management, hand pulled European beachgrass on approximately 6 hectares (15 acres) of the south spoil area. The 4-month project cost $11,500; most of these costs covered the crew supervisor’s salary and transport vehicle charges. Another European beachgrass removal project around the south spoil areas of the Coos Bay North Spit, included burning European beachgrass, followed by scarification using a bulldozer in March 1994. By August, most of the area had resprouted (Oregon Department of Fish and Wildlife 1996). New beachgrass sprouts are relatively easy to remove. However, initial and maintenance work can be costly and labor intensive. At the Coos Bay North Spit, eradication of European beachgrass using 91.4 centimeters (36 inches) of sprayed seawater was attempted in 1996. The saltwater application was not effective because desiccated sand layers did not allow seawater penetration to the grass’s root zone. Future experimentation using wetting agents to achieve water penetration on small-scale applications could demonstrate potential applicability of this technique (G. Dorsey, U.S. Army Corps of Engineers, pers. comm. 1997).

The New River Spit is another key nesting area for the western snowy plover that is managed by the Coos Bay U.S. Bureau of Land Management. Each year since 1998, the U.S. Bureau of Land Management has used heavy equipment (i.e., front-end loader, bulldozer) to remove European beachgrass from in and around a target 99 restoration site. Typically, the bulldozer is used to push the beachgrass into depressions and bury it under several feet of sand, or to push sand and beachgrass out into the surf zone. Just over two miles of foredune have been lowered and select areas along the foredune have been removed to allow ocean surf to overwash into interior portions of the spit. The overwashing aids in scouring vegetation and appears to self-maintain portions of the overwashes throughout the restoration area. By 2002, approximately 48 hectares (120 acres) of foredune and overwash were cleared of beachgrass (Jim Heaney, Bureau of Land Management, pers. comm. 2003).

Work at Lanphere-Christensen Dune Preserve in Humboldt County, California, showed that hand pulling can eliminate European beachgrass, but 3 years of multiple maintenance treatments were required (Pickart and Sawyer 1998). Use of heavy equipment (e.g., “V” ripper) and herbicides may be more cost-effective; however, resprouting of the grass occurs, necessitating follow-up, manual pulling for long-term beachgrass removal (A. Pickart, The Nature Conservancy, pers. comm. 1997).

The effective strategy used by the California Department of Parks and Recreation to remove beachgrass at Marina Dunes and Salinas River State Beaches, Monterey Bay, included multiple herbicide applications of 10 percent Round-Up. Approximately 25 patches of beachgrass covering a total of approximately 0.5 hectare (1.3 acres) have been treated along a 6.4-kilometer (4-mile) section of beach. Each patch of beachgrass was sprayed every 3 months over a 3-year period. All treated sites were marked so that they could be easily located and monitored for regrowth and spread.

Current plans include beachgrass removal on approximately 30 hectares (75 acres) at Zmudowski State Beach at the Pajaro River mouth (D. Dixon in litt. 1998).

Western snowy plover habitat restoration efforts at the Leadbetter Point Unit of the Willapa National Wildlife Refuge began in 2002 and continue. American beachgrass and some European beachgrass have been mechanically removed, clearing approximately 25 hectares (63 acres) as of 2006. In addition, cuts have been made through the foredune and oystershell placed to cover 11 hectares (28 acres) within the restored area (K. Brennan in litt. 2006).

Pickart (1997) suggested that chemical treatment of European beachgrass is likely to be the most cost-effective method used to date. Herbicides that have been used for 100
this purpose are glyphosates (trade names Rodeo and Round-Up). The most effective period for herbicide treatment of beachgrass is during its flowering stage (Wiedemann 1987); plants should be treated during periods of active growth (Pickart 1997). However, potential adverse biological impacts to other native plants and animals must be considered when using herbicides, and selective spraying may be difficult in some areas. Chemical treatment in active western snowy plover nesting areas may need to be limited to the period outside the breeding season in certain areas to avoid disturbing nesting western snowy plovers.

Additional management options for beach and dune erosion control are needed.

Beachgrass continues to be used because it has been tried successfully in the past, nursery stock is available, and field planting technology is well known. However, negative aspects of its monoculture are recognized. Proper planting and management of a mixture of native vegetation, together with the provision of walkways for pedestrian traffic and the elimination of horse traffic, cattle grazing, and off-road vehicles, may result in stabilization as effective as beachgrass, yet there has been minimal experimentation with this technique (Barbour and Major 1990). e. Off-Road Vehicle Restrictions and Management
Management strategies to reduce off-road and other vehicle impacts have been implemented at some western snowy plover breeding areas. At Pismo/Oceano Dunes State Vehicular Recreation Area, California, management strategies include fenced- off nesting areas; placement of exclosures around nests; restrictions on vehicle speed and access areas; and requirements that car campers remove all trash. At Pismo/Oceano Dunes State Vehicle Recreation Area, the California Department of Parks and Recreation, Off-Road Vehicle Division, has developed an interim management plan, which is adapted annually in coordination with us to address what effects current management measures have on hatching rates and fledging success, as well as recruitment into the western snowy plover population (California Department of Parks and Recreation 2005). The Off-Road Vehicle Division of the California Department of Parks and Recreation is now funding the development of a habitat conservation plan (in anticipation of applying for a section 10(a)(1)(B) permit under the Endangered Species Act) for the Pismo/Oceano Dunes State Vehicular Recreation 101
Area and other State parks within the San Luis Obispo Coast District of the California Department of Parks and Recreation.

The conservation issues for western snowy plovers and California least terns at the Pismo/Oceano Dunes State Vehicular Recreation Area are directing the development of the habitat conservation plan, but other species also will be covered. This plan will evaluate the effects that recreation and park management activities are having on the covered species.

On Camp Pendleton, the Marine Corps conducts its vehicle operations in and near nesting areas in ways that minimize impacts to western snowy plovers. Under the Marine Corps’ Base Regulations all training activities, including vehicle training, are prohibited within 300 meters of fenced nesting areas during the breeding season (1 March to 15 September). Further, amphibious vehicles are directed to transit adjacent to nesting areas with tracks in the ocean whenever possible (U.S. Marine Corps 2006).

On the Don Edwards San Francisco Bay National Wildlife Refuge, part of the main access road (Marshlands Road) is closed to motorized vehicles from April 1 to August 31, to protect western snowy plovers nesting near the roadway. Highway traffic cones and ribbons are installed to discourage vehicle access to nesting areas on roads and levees (J. Albertson in litt. 1999).

In 1995, after the Oregon Dunes National Recreation Area completed its management plan, the U.S. Forest Service petitioned the Oregon Parks and Recreation Department to close several kilometers of beach that had been open to vehicles. Resulting closures reduced conflicts between off-highway vehicles and nonmotorized recreationists, western snowy plovers, and other wildlife (E.Y. Zielinski and R.W.

Williams in litt. 1999).

Leadbetter State Park (immediately to the south of Willapa National Wildlife Refuge) is closed to beach driving from April 15 to the day after Labor Day. The entire beach along Willapa National Wildlife Refuge is closed to driving year round, except during razor clam openers (K. Brennan in litt. 2006). Diligent surveillance and 102
enforcement by applicable agencies is extremely important due to the potential for violations.
f. Population Monitoring
Western snowy plover researchers in Washington, Oregon and California conduct intensive population monitoring programs. Tasks include some or all of the following: (1) conducting winter and breeding season window surveys; (2) banding adults and chicks; (3) determining nest success; (4) determining fledging success, (5) monitoring and documenting brood movements; and (6) collecting general observational data on predators.

The Point Reyes Bird Observatory has been monitoring the distribution and breeding success of western snowy plovers since 1977. Monitoring at Vandenberg Air Force Base has been conducted by Point Reyes Bird Observatory and SRS Technologies.

Additionally, Santa Barbara County-supported volunteer docents stationed at Surf Station, within Vandenberg Air Force Base, keep tallies of numbers of visitors, violations prevented, and predators seen (R. Dyste in litt. 2004). The U.S. Geological Survey Biological Resources Division monitored western snowy plovers in San Diego County from 1994 to 1998. Teams led by Elizabeth Copper, Robert Patton, Shauna Wolf, and Brian Foster have monitored western snowy plovers in San Diego County since 1999 for military installations. The Oregon Natural Heritage Program and The Nature Conservancy have conducted western snowy plover monitoring since 1990 in Oregon. The Point Reyes Bird Observatory, Oregon Natural Heritage Program, and U.S. Geological Survey, Biological Resources Division, also band western snowy plovers at some locations (Figure 10). The California Department of Parks and Recreation conducts annual monitoring throughout the state and at the Pismo/Oceano Dunes State Vehicular Recreation Area (J. Didion in litt. 1999). Mad River Biologists and Humboldt State University are currently conducting intensive population monitoring in northern California. Department of Defense installations continue to maintain long-term programs for monitoring and management of western snowy plover populations and predators in San Diego and Ventura Counties, including programs at Camp Pendleton, Naval Amphibious Base Coronado, Naval Radio Receiving Facility Imperial Beach, North Island, and San Clemente Island. 103
Figure 10. Banding a western snowy plover chick (photo by Bonnie Peterson with permission)
g. Salt Pond Management
Intensive management at the Moss Landing Wildlife Area has made a major contribution to western snowy plover breeding success in the Monterey Bay area.

Management by Point Reyes Bird Observatory staff, in coordination with the California Department of Fish and Game, has been ongoing since 1995.

Management activities include draw-down of water levels in part of the salt ponds at the beginning of the nesting season to provide dry sites for nests, and flooding of remnant wet areas twice per month through the nesting season to maintain foraging habitat for adults and their young. Predator control is conducted by the U.S.

Department of Agriculture, Wildlife Services Branch.

The Don Edwards San Francisco Bay National Wildlife Refuge manages a former salt pond called the “Crescent Pond” (within location CA-36, mapped in Appendix L) for 104
western snowy plovers by reducing the water levels prior to the breeding season. In the early 1990s, this pond was mostly unvegetated salt flat, but since then native pickleweed (Salicornia virginica) has slowly increased on the site, making the areas less valuable for western snowy plover nesting habitat. The Refuge has begun to conduct winter flooding in the Crescent Pond to reduce vegetative cover and improve western snowy plover nesting habitat.

The 2003 acquisition of Cargill’s West Bay, Alviso, and Baumberg Salt Ponds in the South Bay by California Department of Fish and Game and Don Edwards San Francisco Bay National Wildlife Refuge will greatly further the goal of achieving 810 hectares (2,000 acres) of ponds managed for western snowy plover habitat (see Recovery Action 2.6). The Refuge’s long-term management plans for these areas will include management that is compatible with western snowy plover and will coordinate with the recovery goals of this Recovery Plan (J. Albertson, pers. comm. 2005). Many of the salt ponds are currently used for breeding and wintering by western snowy plovers. San Francisco Bay Bird Observatory is assisting the Refuge with salt marsh management and western snowy plover monitoring. h. Habitat Acquisition
Acquisition and management of key sites is an important conservation effort. In October 1998, The Nature Conservancy transferred the approximately 193-hectare (483-acre) Lanphere-Christensen Dunes Preserve (part of Mad River Mouth and Beach, California, CA-7) to us for conservation purposes. The area will be managed by the Humboldt Bay National Wildlife Refuge for natural resources, including the western snowy plover. In October 1998, the Port of San Diego announced an agreement enabling approximately 560 hectares (1,400 acres) of Western Salt Company land (CA-131) to be managed by the San Diego National Wildlife Refuge.

The salt ponds are a western snowy plover nesting and wintering area. As noted above, Cargill’s transfer of the West Bay, Alviso, and Baumberg salt ponds, including 6,110 hectares (15,100 acres), to California Department of Fish and Game and Don Edwards San Francisco Bay National Wildlife Refuge was completed in 2003; portions of this area will be managed as western snowy plover habitat. 105
i. Use of Volunteers
Volunteers contribute to the conservation of western snowy plovers and their habitat at many beach locations, including Morro Bay and Oceano Dunes State Vehicular Recreation Area, Point Reyes National Seashore, and Golden Gate National Recreation Area. Volunteers and docents assist public land managers in many ways (Appendix K), including informing park visitors about threats to the western snowy plover, reducing human and pet disturbances, and assisting with direct habitat enhancement (e.g., manual removal of European beachgrass; Figure 11). In 1998, the We
ste rn
Sn ow
y Plo
ver Gu
ard ian
Pr ogr
am was
de vel
op ed
to assi
st the
co nse
rva tion
an d
rec ove
ry of western snowy plovers in Monterey Bay. This program is mainly a volunteer effort by local citizens who assist in protecting western snowy plovers through monitoring, reporting, and educational activities (D. Dixon in litt. 1998). 106
Figure 11. High school students removing European beachgrass (photo by Kerrie Palermo, with permission).
j. Public Outreach and Education
Public land managers and private conservation organizations have produced public educational materials, including brochures, posters, flyers, and informational/interpretative signs regarding western snowy plovers (Appendix K).

Environmental education/interpretation is recognized by land management agencies as an important tool that supports their mission of resource stewardship. Increased understanding and appreciation of natural resources (specifically threatened and endangered species) often results in increased public support. This support is not easily measured and when the audience is children, results may not be seen until they reach adulthood. However, those agencies conducting western snowy plover education to date have found a positive response by individuals. In Oregon, on-site monitors of the U.S. Forest Service (Oregon Dunes National Recreation Area) and U.S. Bureau of Land Management report a willingness of the majority of contacted individuals to comply with restrictions after better understanding the reasons for them.

The La Purisima Audubon Society, Santa Barbara County, produced an educational video about the western snowy plover and the California least tern in 1999. It was distributed to public schools and museums within Santa Barbara County in 2000. 107
k. Section 6 Cooperative Agreements
Section 6 of the Endangered Species Act allows us to enter into cooperative agreements with states that establish and maintain active programs for the conservation of listed species. Through funding under section 6, those states assist the recovery of endangered and threatened species and monitor their status.

Between 2000 and 2006, traditional section 6 funds have been used for creation of a docent program at Silver Strand State Beach in California ($8,300); development of a water management plan at Moss Landing Wildlife Area, California ($4,886); surveillance and protection of snowy plover nests on California beaches ($92,000); and surveys, nest monitoring, protecting nests with exclosures, collecting data on human uses of beaches, and encouraging beach uses compatible with snowy plovers in Oregon ($64,386) and Washington ($48,677). HCP Planning grants were used for development of a habitat conservation plan to address management of beach use by the Oregon Parks and Recreation Department ($103,950) and development of an Environmental Impact Statement for this Habitat Conservation Plan ($200,000). A Recovery Land Acquisition grant ($307,000) supported purchase of a conservation easement on 89 hectares (220 acres) of western snowy plover habitat along 3.7 kilometers (2.3 miles) of the Elk River Spit.

3. Conservation Efforts on Private Lands
Private landowners interested in conservation efforts for western snowy plovers and coastal dune habitats have made important contributions to recovery efforts for coastal dune species. At Ormond Beach, California, Southern California Edison has enhanced approximately 60 hectares (150 acres) of degraded wetlands and coastal dune habitat for several special status species, including the western snowy plover and California least tern (D. Pearson, Southern California Edison, pers. comm. 1996). 108

4. Federal Regulatory Program
a. Critical Habitat
On March 2, 1995, we published a proposed rule to designate critical habitat for western snowy plover at 28 areas along the coast of California, Oregon, and Washington (U.S. Fish and Wildlife Service 1995b). At that time, critical habitat was proposed to fulfill an outstanding requirement under section 4 of the Endangered Species Act to highlight important habitat areas on which activities that require Federal actions need to be evaluated under section 7 of the Endangered Species Act.

A funding moratorium by the U.S. Department of the Interior for listing actions was in place during the period April 1995 to April 1996. We subsequently acknowledged a serious backlog of listing actions and the need to prioritize them (U.S. Fish and Wildlife Service 1996b). Hence, we developed guidance for assigning relative priorities to listing actions conducted under section 4 of the Endangered Species Act during fiscal years 1998 and 1999 (U.S. Fish and Wildlife Service 1998).

Designation of critical habitat was placed in the lowest priority (Tier 3). Under this guidance, we placed higher priority on listing imperiled species that currently have limited or no protection under the Endangered Species Act than on devoting limited resources to the process of designating critical habitat for currently-listed species. In addition, we found that because the protection afforded by critical habitat designation applies only to Federal actions, such designation provides little or no additional protection beyond the “jeopardy” prohibition of section 7 of the Endangered Species Act, which also applies only to Federal actions (U.S. Fish and Wildlife Service 1998).

In December 1995, legal challenges by the Environmental Defense Center, Santa Barbara, California, against the U.S. Department of the Interior to finalize designation of critical habitat for the western snowy plover were overruled by the California District Court (U.S. District Court, Central District of California 1995). At that time, the Court’s order was based on its decision that lack of funding prevented the Secretary of the Interior from taking final action on proposals for designating critical habitat. However, on November 10, 1998, the U.S. District Court for the Central District of California ruled that the Secretary of the Interior must publish a final designation of critical habitat for the western snowy plover before December 1, 1999 (U.S. District Court, Central District of California 1998). 109
A final rule designating critical habitat was published on December 7, 1999 (U.S.

Fish and Wildlife Service 1999). In May of 2002 the Coos County Board of County Commissioners, Friends of Oceano Dunes, and Concerned Citizens for western Lane County filed a complaint asking for invalidation of the rule. The United States moved for voluntary remand to reconsider the economic analysis and for partial vacatur of the existing designation. On July 19, 2003, the District Court for the District of Oregon granted the United States’ motion, ordering the Service on remand to consider the economic impact analysis and ensure that the new rule is based on the best scientific evidence available. This Order was converted to Judgment on July 2, 2003. Based on the potential for harm to the population, at the Service’s request the court left most of the established units in place during the redesignation process, but vacated two units in southern California and two units in Washington.

On December 17, 2004, we published a new proposal to designate critical habitat for the Pacific coast distinct population segment of the western snowy plover (U.S. Fish and Wildlife Service 2004b). The final rule to designate critical habitat was published on September 29, 2005 (U.S. Fish and Wildlife Service 2005). This rule designated critical habitat in 32 units, compared to 28 units in the 1999 critical habitat final rule, but covers only 4,921 hectares (12,145 acres) compared to 7,881 hectares (19,474 acres) in the 1999 rule. Of the 32 units, 23 are in California, 5 are in Oregon, and 3 are in Washington. Of the total acreage, 1,002 hectares (2,478.5 acres), or 20 percent, are on Federal lands; 2620.5 hectares (6,474 acres), or 53 percent, are on land owned by States or local agencies; and 1294.5 hectares (3,191 acres), or 26 percent, are privately-owned.

It is important to understand what critical habitat means and how it differs from this recovery plan. Section 3 of the Endangered Species Act defines critical habitat to mean: (i) the specific areas within the geographical area occupied by the species at the time it is listed on which are found those physical or biological features (I) essential to the conservation of the species and (II) which may require special management considerations or protection; and (ii) specific areas outside the geographical area occupied by the species at the time it is listed, upon determination that such areas are essential for the conservation of the species. The term “conservation” is defined in section 3 as “the use of all methods and procedures which are necessary to bring any endangered species or threatened species to the 110
point at which the measures provided pursuant to this Act are no longer necessary.” Therefore, critical habitat is to include biologically suitable areas necessary to recovery of the species.

Section 7 of the Endangered Species Act requires Federal agencies to consult with us to evaluate the effects that any activities they fund, authorize, or carry out may have on designated critical habitat. Agencies are required to ensure that such activities are not likely to adversely modify (e.g., damage or destroy) critical habitat. Because the issuance of permits under section 10(a)(1)(B) of the Endangered Species Act constitutes a Federal action or connection and is subject to an internal section 7 consultation, habitat conservation plans developed for actions on private lands must also analyze the potential for adverse modification of critical habitat. Accordingly, where Federal activities may affect western snowy plover critical habitat, we will consult with Federal agencies under section 7 to ensure that these actions do not adversely modify critical habitat.

Critical habitat designation does not create a wilderness area, preserve, or wildlife refuge, nor does it close an area to human access or use. It applies only to activities sponsored at least in part by Federal agencies. Such federally-permitted land uses as grazing and recreation may take place if they do not adversely modify critical habitat.

Designation of critical habitat does not constitute a land management plan, nor does it signal any intent of the government to acquire or control the land. Therefore, if there is no Federal involvement (e.g., Federal permit, funding, or license), activities of a private landowner, such as farming, grazing, or constructing a home, generally are not affected by a critical habitat designation, even if the landowner’s property is within the geographical boundaries of critical habitat (U.S. Fish and Wildlife Service 1993c). Without a Federal connection to a proposed action, designation of critical habitat does not require that landowners of State or other non-Federal lands do anything more than they would otherwise do to avoid take of listed species under provisions of section 9 of the Endangered Species Act.

By comparison, a recovery plan delineates site-specific management actions that we believe are required to recover and/or protect listed species, establishes objective, measurable criteria for downlisting or delisting the species, and estimates time and cost required to carry out these actions. A recovery plan is not a regulatory document 111
and does not obligate cooperating or other parties to undertake specific tasks or expend funds.

Critical habitat designation is not necessarily intended to encompass a species’ entire current range. Recovery plans, however, address all areas determined to be important for recovery of listed species and identify needed management measures to achieve recovery. Because critical habitat designations may exclude areas based on factors such as economic cost, approved or pending management plans, or encouragement of cooperative conservation partnerships with landowners, the areas identified in recovery plans as important for recovery of the species may not be identical to designated critical habitat. The recovery units described in this recovery plan include but are not restricted to the 32 areas designated as critical habitat: Damon Point, Midway Beach, Leadbetter Point, Bayocean Spit, Baker/Sutton Beaches, Siltcoos to Tenmile, Coos Bay North Spit, and Bandon to Floras Creek in Recovery Unit 1; Lake Earl, Big Lagoon, McKinleyville area, Eel River area, MacKerricher Beach, and Manchester Beach in Recovery Unit 2; Point Reyes Beach, Limantour Spit, Half Moon Bay, Santa Cruz Coast, Monterey Bay Beaches, and Point Sur Beach in Recovery Unit 4; San Simeon Beach, Estero Bay, Devereaux Beach, Oxnard Lowlands in Recovery Unit 5; and Zuma Beach, Santa Monica Bay, Bolsa Chica area, Santa Ana River Mouth, San Onofre Beach, Batiquitos Lagoon, Los Penasquitos, and South San Diego in Recovery Unit 6. Implementation of the recovery actions in this recovery plan (e.g., monitoring, habitat improvement, nest protection, recreation management) may not be limited to designated critical habitat areas.
b. Section 9 Take Prohibitions
Section 9 of the Endangered Species Act of 1973, as amended, prohibits any person subject to the jurisdiction of the United States from taking (i.e., harassing, harming, pursuing, hunting, shooting, wounding, killing, trapping, capturing, or collecting) listed wildlife species. It is also unlawful to attempt such acts, solicit another to commit such acts, or cause such acts to be committed. Regulations implementing the Endangered Species Act (50 CFR 17.3) further define “harm” to include significant habitat modification or degradation that results in the killing or injury of wildlife by significantly impairing essential behavioral patterns including breeding, feeding, or 112
sheltering. “Harass” means an intentional or negligent act or omission that creates the likelihood of injury to wildlife by annoying it to such an extent as to significantly disrupt normal behavioral patterns, which include, but are not limited to, breeding, feeding, or sheltering.

As an example under the authority of section 9 of the Endangered Species Act, on May 15, 1998, we received preliminary injunctive relief against the Town of Plymouth, Massachusetts, because their beach management failed to prevent take (killing) of a piping plover chick by an off-road vehicle (U.S. District Court for Massachusetts 1998). The judge’s order prohibited off-road vehicle traffic through the piping plover’s nesting season unless the town implemented specific management measures to preclude take, including twice-daily monitoring of nests and a 400-meter (1,148-foot) buffer of protected habitat for newly-hatched chicks.

The proposed special rule under section 4(d) of the Endangered Species Act (U.S.

Fish and Wildlife Service 2006b) would exempt most recreational and commercial activities within a county from section 9 prohibitions on take of western snowy plovers, if documentation of conservation actions was provided and populations within the county met targets based on the Management Goal Breeding Numbers in Appendix B of the recovery plan. Research and monitoring actions would continue to require recovery permits under section 10(a)(1)(A) of the Endangered Species Act. c. Section 10 Permits
Section 10 of the Endangered Species Act and related regulations provide for permits that may be granted to authorize activities otherwise prohibited under section 9, for scientific purposes or to enhance the propagation or survival of a listed species (i.e., section 10(a)(1)(A) permits). These permits have been granted to certain biologists of conservation organizations (e.g., Point Reyes Bird Observatory and Oregon Natural Heritage Program) and Federal and State agencies to conduct western snowy plover population monitoring and banding studies and construct predator exclosures.

It is also legal for employees or designated agents of certain Federal or State agencies to take listed species without a permit if the action is necessary to aid sick, injured, or orphaned animals or to salvage or dispose of a dead specimen. 113
Section 10(a)(1)(B) of the Endangered Species Act also allows permits to be issued for take of endangered and threatened species that is “incidental to, and not the purpose of, carrying out an otherwise lawful activity” if we determine that certain conditions have been met. An applicant for an incidental take permit must prepare a habitat conservation plan that specifies the impacts of the take, the steps the applicant will take to minimize and mitigate the impacts, funding that will be available to implement these steps, alternative actions to the take that the applicant considered, and the reasons why such alternatives are not being utilized. Conditions that we must meet include a determination: (1) whether the taking will be incidental, (2) whether the applicant will minimize and mitigate the impacts of such taking to the maximum extent possible, (3) that adequate funding for the recovery will be provided, (4) that the taking will not appreciably reduce the likelihood of the survival and recovery of the species in the wild, and (5) of any other measures that we may require as being necessary or appropriate for the recovery plan. Section 10(a)(1)(B) of the Endangered Species Act provides for permits that have the potential to contribute to conservation of listed species. Such permits are intended to reduce conflicts between the conservation of listed species and economic activities, and to develop partnerships between the public and private sectors.
d. Section 7 Requirements and Consultations
Section 7(a)(1) of the Endangered Species Act requires all Federal agencies to “utilize their authorities in furtherance of the purposes of [the] Act by carrying out programs for the conservation of endangered species and threatened species”. Hence, Federal agencies have a greater obligation than do other parties, and are required to be pro-active in the conservation of listed species regardless of their requirements under section 7(a)(2) of the Act. Section 7(a)(2) of the Endangered Species Act requires Federal agencies to consult with us prior to authorizing, funding, or carrying out activities that may affect listed species. Section 7 obligations have caused Federal land management agencies to implement western snowy plover protection measures that go beyond those required to avoid take; for example, eradicating European beachgrass and conducting research on threats to western snowy plovers.

Other examples of Federal activities that may affect western snowy plovers along the Pacific coast, thereby triggering a section 7 consultation, include permits for sand management activities or major restoration projects that affect coastal processes or 114
that are targeted to protect other species on Federal lands such as dune plants (National Park Service, U.S. Department of the Interior); disposal of dredged materials (U.S. Army Corps of Engineers); military training (U.S. Department of Defense); and funding to public agencies for projects to repair beach facilities, such as public access paths (Federal Emergency Management Agency). e. Other Federal Regulations, Executive Orders, and Agreements Section 404 of the Clean Water Act, as amended, and section 10 of the Rivers and Harbors Act of 1899 are the primary Federal laws that could provide some protection of nesting and wintering habitat of the western snowy plover that is determined by the U.S. Army Corps of Engineers (Corps) to be wetlands or historic navigable waters of the United States. Excavation or placement of any fill material (including sand) below the high tide line, as defined under 33 CFR, Section 328.3(d), Definition of Waters of the United States, also requires a permit from the U.S. Army Corps of Engineers.

Executive Order 11644, Use of Off-Road Vehicles on Public Lands, and Executive Order 11989, Off-Road Vehicles on Public Lands, pertain to lands under custody of the Secretaries of Agriculture, Defense, and Interior (except for Native American Tribal lands). Executive Order 11644 requires administrative designation of areas and trails where off-road vehicles may be permitted. Executive Order 11989 states that “... the respective agency head shall, whenever he determines that the use of off- road vehicles will cause or is causing considerable adverse effects on the soil, vegetation, wildlife, wildlife habitat ... immediately close such areas or trails to the type of off-road vehicles causing such effects, until such time as he determines that such effects have been eliminated and that measures have been implemented to prevent future recurrence”. Compliance with this executive order would promote prohibitions or restrictions on off-road vehicles so that they are not allowed to adversely affect sensitive habitats used by western snowy plovers.

Executive Order 11988, Floodplain Management, and Executive Order 11990, Protection of Wetlands, provide protective policies that apply to western snowy plover habitats. Executive Order 11988 mandates that all Federal agencies avoid direct or indirect support of floodplain development wherever there is a practicable 115
alternative. Executive Order 11990 mandates that all Federal agencies shall “provide leadership and shall take action to minimize the destruction, loss or degradation of wetlands, and to preserve and enhance the natural and beneficial values of wetlands...” Compliance with Executive Order 11988 would promote protection of beach and dune habitats through restrictions on development within floodplains.

Application of Executive Order 11990 would promote protection of wetland habitats used by western snowy plovers.

Executive Order 13112, Invasive Species, directs Federal agencies to prevent the introduction of invasive species; control their populations in a cost-effective and environmentally sound manner; monitor invasive species; restore native species and habitat conditions in ecosystems that have been invaded; conduct research and develop technologies to prevent their introduction; and promote public education on invasive species and the means to address them. This executive order also requires that a Federal agency “not authorize, fund, or carry out actions that it believes are likely to cause or promote the introduction or spread of invasive species...” Compliance with this executive order would enhance western snowy plover habitats through (1) avoidance of use, approval, or funding the planting of invasive species like European beachgrass; and (2) active programs to remove this invasive species and restore coastal dune habitats with native plant species.

The Fish and Wildlife Coordination Act (16 U.S.C. 661-667e), as amended, requires that whenever a proposed public or private water development project is subject to Federal permit, funding, or license, the conservation of fish and wildlife resources shall be given equal consideration. This Act also requires that project proponents shall consult with us and the State agency responsible for fish and wildlife resources.

Compliance with the Fish and Wildlife Coordination Act highlights the importance of considering and providing for the habitat needs of fish and wildlife resources when reviewing projects that would adversely affect these resources.

The National Environmental Policy Act of 1969, (42 U.S.C. 4321-4347), as amended, requires that each Federal agency prepare an environmental impact statement on the potential environmental consequences of major actions under their jurisdiction.

Environmental impact statements must include the impacts on ecological systems, any direct or indirect consequences that may result from the action, less 116
environmentally damaging alternatives, cumulative long-term effects of the proposed action, and any irreversible or irretrievable commitment of resources that might result from the action. Compliance with the National Environmental Policy Act highlights the need to disclose, minimize, and mitigate impacts to biological resources, including western snowy plovers.

The Coastal Zone Management Act of 1972 (16 U.S.C. 1451-1464), as amended, established a program for states to voluntarily develop comprehensive programs to protect and manage coastal resources. To receive Federal approval and funding under this Act, states must demonstrate that they have programs and enforceable policies that are sufficiently comprehensive and specific to regulate land uses, water uses, and coastal development, and must have authorities to implement enforceable policies. Local coastal plans, local comprehensive plans, and implementing measures by coastal planning jurisdictions pursuant to the Coastal Zone Management Act should be developed, updated, and implemented with protective measures for western snowy plovers.

Western snowy plovers are protected under the Migratory Bird Treaty Act of 1918 (16 U.S.C. 703-712), as amended. Under the Migratory Bird Treaty Act, prohibited acts include pursuing, hunting, shooting, wounding, killing, trapping, capturing, or collecting any migratory bird, nest, or eggs without a permit from the U.S. Fish and Wildlife Service.

5. State Regulatory Protection, Policies, and Agreements In Washington, Oregon, and California, each state holds title to, and has regulatory jurisdiction over, the coastal intertidal zone. In Washington, the area between mean high tide to extreme low tide is the seashore conservation area under the authority of the Washington State Parks and Recreation Commission. In California, the California State Lands Commission has regulatory authority to the mean high tide line along the California coast.

In Oregon, the Oregon Parks and Recreation Department administers the State beach for the ocean shore recreation area, which is defined as the area between the line of extreme low water and the statutory vegetation line, which is a line surveyed to the 117
approximate line of vegetation that existed in 1969 (Oregon Revised Statutes 390.770). The Oregon Division of State Lands also has jurisdiction over waters of the state along the Pacific coast to the line of highest tide or the line of established vegetation, whichever is higher. Therefore, the Oregon Parks and Recreation Department has direct jurisdiction, authority, and responsibility for management of western snowy plover habitats in the State of Oregon, which owns not only to the mean high tide line, which is western snowy plover foraging habitat, but also into the vegetation line, which is essentially the dry sand area used by western snowy plovers for nesting.

State coastal planning and regulatory agencies, such as the California Coastal Commission, require preparation of local coastal zone management plans by local coastal municipalities. These local coastal zone management plans must comply with the Coastal Zone Management Act of 1972 regarding protection of coastal resources, including natural resources. Under the California Coastal Management Program, coastal resources are managed and cumulative impacts addressed through: (1) coastal permits and appeals; (2) planning and implementation of local coastal programs; and (3) Federal consistency review. However, effective management of cumulative impacts is difficult under the existing management framework because multiple jurisdictions have varying policies and standards in different geographic areas (California Coastal Commission 1995). Through the Coastal Commission’s regional cumulative assessment program, cumulative impacts to coastal resources can be addressed through the periodic review of local coastal programs. In California, most local coastal programs and general plans were completed prior to 1993 (when we listed the western snowy plover as a threatened species); therefore, many do not reflect protective measures specifically for the western snowy plover.

The Oregon Department of Land Conservation and Development is the designated coastal zone management agency for the State of Oregon. The State of Oregon's land use planning system has several elements that are related to conservation of western snowy plovers and their habitats. In Oregon, local jurisdictions (cities and counties), service districts, and State agencies are required to develop Local Comprehensive Plans and Implementing Measures, such as zoning and land division ordinances, to effect these plans. Each plan must satisfy a set of 19 goals established through Oregon land use law and policy. Plans must be reviewed by the Land Conservation 118
and Development Commission for consistency with these goals before they can be put into effect. Several of the planning goals have application to, or should be considered during, planning for western snowy plover conservation and recovery.

These goals include: Goal 5 - Open Spaces, Scenic and Historic Areas, and Natural Resources; Goal 7 - Areas Subject to Natural Disasters and Hazards; Goal 8 - Recreational Needs; Goal 16 - Estuarine Resources; Goal 17 - Coastal Shorelands; and Goal 18 - Beaches and Dunes.

Taken in aggregate, the elements of these goals that can contribute to western snowy plover recovery include:

C several requirements for protection of wildlife habitat; C requiring protection of estuarine ecosystems including habitats, diversity, and other natural values;
C establishing that uses of beaches and dunes shall be based on factors including the need to protect areas of critical environmental concern and significant wildlife habitat;
C requiring that coastal plans provide for uses of beaches and dunes that are consistent with their ecological values and natural limitations; C requiring an evaluation of the beneficial effects to natural resources from allowing continuation of natural events that are hazardous to human developments (such as erosion and ocean flooding);
C establishing a preference for nonstructural solutions to erosion and flooding of coastal shorelands over structural approaches (such as seawalls and rip-rap); C requiring that development of destination resorts be compatible with adjacent land uses and maintain important natural features such as threatened and endangered species habitats;
C encouraging coordination among State, Federal, and local governmental agencies while developing recreation plans, and discouraging development of recreation plans that exceed the carrying capacity of the landscape; C encouraging planning for Open Space, Scenic and Historic Areas, and Natural Resources (Goal 5), Recreational Needs (Goal 8), and Coastal Shorelands (Goal 17) in close coordination; and
C allowing dune stabilization programs only when in conformance with the overall comprehensive plan and after assessment of the potential impacts. 119
Some aspects of these planning goals could be interpreted to be contrary to western snowy plover conservation and recovery when viewed in isolation. However, when viewed in the context of the entire goal or all the planning goals, these elements should be compatible with western snowy plover conservation and carefully-planned habitat restoration activities. Two such elements are the directive to increase recreational access to coastal shorelands and the restrictions placed on dune grading and removal of vegetation. Goal 17 - Coastal Shorelands directs local governments and the Oregon Parks and Recreation Department to develop a program to increase public access. In many areas, recreational use of western snowy plover habitat during the nesting season is detrimental to or incompatible with western snowy plover conservation. However, this goal also recognizes that many shorelands have unique or exceptional natural area values, includes the objective of reducing adverse impacts to fish and wildlife habitat associated with use of coastal shorelands, clearly establishes that significant wildlife habitat shall be protected, establishes that uses of such habitat areas shall be consistent with protection of natural values, and directs recreation plans to provide for "appropriate" public access and recreational use. Goal 18 - Beaches and Dunes directs local governments and State and Federal agencies to regulate actions in beach and dune areas to minimize any resulting erosion and only allows foredune breaching to replenish interdune areas or in the case of an emergency. Western snowy plover habitat restoration efforts in areas that have been overtaken by European beachgrass (Ammophila arenaria) may involve foredune breaching, vegetation removal, dune grading, and other actions that will remove the European beachgrass and restore the natural beach and dune processes of sand movement, including erosion and deposition. However, this goal also recognizes the need to protect areas of critical environmental concern, areas of biological importance, and areas with significant habitat value, specifically identifies removal of "desirable" vegetation as an action requiring minimization of erosion, and requires that any foredune breaching be consistent with sound principles of conservation.

The Washington State Parks and Recreation Commission administers the Seashore Conservation Act of 1988 in accordance with the Revised Code of Washington and the Washington Administrative Code. The Seashore Conservation Area (Revised Code of Washington 43.51) emphasizes the importance of beaches to the public for recreational activities. In designating beach areas to be reserved for pedestrian use, it 120
considers natural resources, including protection of shorebird and marine mammal habitats, preservation of native beach vegetation, and protection of sand dune topography. Chapter 352-37 (Ocean Beaches) of the Washington Administrative Code requires local governments within the Seashore Conservation Area to prepare recreation management plans that designate at least 40 percent of the ocean beach for use by pedestrians and nonmotorized vehicles from April 15 to the day after Labor Day. These regulations also identify restrictions on certain uses within ocean beaches, including motor vehicles, equestrian traffic, speed limits, aircraft, wind/sand sailers, parasails, hovercraft, group recreation events, and beach parking and camping. In 1989, an interagency agreement was signed by the Washington Department of Natural Resources, Washington State Parks and Recreation Commission, Washington Department of Wildlife, and City of Ocean Shores regarding management of mixed uses at Damon Point. The intent of the agreement was to protect western snowy plovers while allowing recreation.

State regulations, policies, and goals for the States of California, Oregon, and Washington provide many protective measures for western snowy plovers. However, because they frequently emphasize public uses of beach habitat, there is potential for conflicts between human uses of the coastal zone and needed management measures for recovery of the western snowy plover.

The California Department of Parks and Recreation has written management guidelines for the western snowy plover which are meant to be used in conjunction with the recovery plan. Management actions will be implemented from the guidelines and may result in changes in how coastal units are operated. Increased emphasis will be required for monitoring, nest area protection, prohibition of certain activities in important nesting areas, and public education.

6. Consultations, Habitat Conservation Plans, and Other Regulatory Actions Through consultations with Federal agencies under section 7 of the Endangered Species Act and through the development of habitat conservation plans with non- Federal agencies developed under section 10 of the Endangered Species Act, we provide nondiscretionary terms and conditions that minimize (sections 7 and 10) and mitigate (section 10) the impacts of covered activities on listed species and their 121
habitat. Several major consultations and habitat conservation planning efforts to benefit the western snowy plover have been completed or are currently under way.

In 1995 our Sacramento Fish and Wildlife Office completed formal consultation with the National Park Service, Golden Gate National Recreation Area, on the effects of their management of Ocean Beach, San Francisco on the western snowy plover.

Ocean Beach experiences tremendous visitor use year-round because of its proximity to San Francisco, yet it supports high numbers of nonbreeding western snowy plovers, which may be present from May through July. The consultation covered actions and policies the National Park Service had taken that resulted in unnecessary harassment of nonbreeding western snowy plovers. Most significant of these measures was their policy not to enforce regulations requiring pets to be leashed and under control by their owners on all National Park Service lands. Data collected by the National Park Service clearly identified that unleashed dogs were the most significant disturbance factor of the many sources of disturbance to western snowy plovers on Ocean Beach. As a result of the consultation, the National Park Service began to enforce their “leash law” along 3.2 kilometers (2 miles) of beach utilized by western snowy plovers. The National Park Service implemented this policy despite vocal and persistent opposition by the San Francisco Society for the Prevention of Cruelty to Animals and other local advocacy groups, including the “Rovers for Plovers”, which organized themselves to challenge the National Park Service’s leash law. These groups were successful in advocating their position in numerous television news stories and articles in local newspapers. At the height of this discourse, the local public radio station held a round-table discussion between the National Park Service, U.S. Fish and Wildlife Service, and Society for the Prevention of Cruelty to Animals, and solicited audience members to call in and identify their viewpoint. The overwhelming majority of callers supported leash law restrictions that would minimize harassment of western snowy plovers.

Our Arcata Fish and Wildlife Office has formally consulted with the U.S. Army Corps of Engineers regarding gravel extraction on the Eel River, California. Gravel mining operations are subject to permits from the U.S. Army Corps of Engineers under Section 404 of the Clean Water Act. The western snowy plover breeds on the Eel River gravel bars. Impacts to the western snowy plover and its designated critical habitat associated with gravel mining operations have been assessed based on nesting 122
surveys and changes to habitat resulting from gravel extraction. The Arcata Fish and Wildlife Office has also worked with Humboldt County, the California Department of Fish and Game, and the California Department of Parks and Recreation to implement additional protections for nesting western snowy plovers at MacKerricher, Manchester, Little River, Humboldt Lagoons, and Prairie Creek State Parks; Clam Beach County Park, and the Eel River Wildlife Area. These measures include installation of nest exclosures, signing, and development of educational material for kiosks. Technical assistance has also been provided to Prairie Creek State Park and MacKerricher State Park on exotic vegetation management programs (J. Watkins in litt. 1999, pers. comm. 2001). A section 7 consultation with the Bureau of Land Management on finalization of a management plan for Humboldt Bay South Spit is expected to be initiated soon (J. Watkins, pers. comm. 2006).

Our Ventura Fish and Wildlife Office is attempting to initiate a regional approach to habitat conservation planning for western snowy plovers and other listed species along Monterey Bay in Monterey County, California. Currently, there are several proposed development projects within the city of Sand City and a “city wide” habitat conservation plan has been prepared for these projects. The City of Sand City has yet to present a complete draft of their habitat conservation plan to the Ventura Fish and Wildlife Office for review. Formerly, the City of Marina was also proposing several coastal developments that were expected to have adverse effects on western snowy plovers, but these projects are no longer planned due to changes in land ownership and other factors. The City of Marina has halted the drafting of a habitat conservation plan for lands within their jurisdiction. We have expressed concerns about projects being presented in a piecemeal fashion, which does not allow an adequate assessment of their cumulative effects, and have recommended a regional approach through preparation of a regional habitat conservation plan. This plan would provide greater conservation benefits to the western snowy plover. In addition to the adverse effects of development on western snowy plovers and their habitat, recreation on the extensive public lands along Monterey Bay is also adversely affecting western snowy plovers. Therefore, public land managers, including our Refuges Division, the California Department of Parks and Recreation, the California Department of Fish and Game, and the Monterey Peninsula Regional Park District, need to be involved in planning efforts along Monterey Bay. 123
Through the consultation process, our Ventura Fish and Wildlife Office determined that a draft biological opinion on Vandenberg Air Force Base’s initial proposed beach management plan for the western snowy plover, concluding that the plan would "likely jeopardize the continued existence of the western snowy plover and adversely modify its critical habitat." Our draft biological opinion of January 2001 pointed out that the Air Force's beach plan would have allowed twice as much nesting habitat to be open to public recreation as was allowed during the 2000 breeding season, and it would have reduced the time the Air Force spends patrolling the beaches by about 80 percent. Based on this feedback, the Air Force subsequently reinitiated consultation on a modified version of the beach management plan, including commitments to signage, information kiosk, and enforcement patrols. The Ventura Fish and Wildlife Office issued a non-jeopardy biological opinion on the modified action in March 2001. Beach opening and full implementation of conservation measures was implemented on May 25, 2001, with hours and days of open beach limited due to limited availability of enforcement personnel. For the next three breeding seasons (2002, 2003, 2004), the Service issued biological opinions on annual beach management plans proposed by the Air Force. In 2004, we had a series of meetings with the Air Force to discuss their beach management strategy and its effects on the western snowy plover. Through a cooperative effort, the Service and the Air Force came to agreement on a 5-year beach management plan that includes many of the same protective measures that had been in place the last several years, yet allows the Air Force to provide recreational access seven days a week. On March 1, 2005, the Ventura Fish and Wildlife Office issued a new non-jeopardy biological opinion on the Air Force’s proposed 5-year beach management plan (2005-2009).

Our Ventura Fish and Wildlife Office is also involved with the development of a habitat conservation plan being funded by the Off-Road Vehicle Division of the California Department of Parks and Recreation for the Pismo/Oceano Dunes State Vehicular Recreation Area and other State parks within the San Luis Obispo District of the California Department of Parks and Recreation. The Ventura Fish and Wildlife Office is also involved in the development of a HCP for the Rancho Guadalupe County Park, Santa Barbara, California. These habitat conservation plans will evaluate and mitigate for effects that recreation and park management activities are having on the covered species, including the western snowy plover. 124
Recent consultations handled by our Newport Field Office include those in response to the New Carissa Oil Spill, a consultation on BLM management actions at the New River Area of Critical Environmental Concern (ACEC), and a consultation on the Integrated Predator Damage Management Program 2002 to 2007. The Oregon Parks and Recreation Department is currently developing a Habitat Conservation Plan that proposes restrictions on some Oregon beaches to help the plover population recover.

The New Carissa oil spill was a long and complicated incident involving a variety of Federal, State, local and private participants. On February 4, 1999, the New Carissa,carrying 359,000 gallons of bunker oil and 37,400 gallons of diesel, grounded on the north spit of Coos Bay and began leaking oil shortly thereafter.

Subsequently, oil and oiled wildlife were observed on the beach. Attempts were made to burn off the oil. The vessel broke into two pieces during the second attempt.

There were three formal consultations associated with the New Carissa between 1999 and 2000. The first consultation addressed the effects of issuing permits for salvage of the New Carissa stern section, the second the effects of restoring recreational access to the Coos Bay north spit, and the third the response efforts led by the Coast Guard. In all three consultations, it was concluded that the proposed actions would not jeopardize the western snowy plover if protective measures required to limit take were implemented.

A consultation on the New River ACEC was completed in 2005. The purpose of the biological opinion was to address a variety of issues: recreation management at Floras Lake where measures were not adequately protecting nesting plovers; the periodic construction of a breach on the New River spit to improve fish and wildlife habitat and alleviate flooding; increased habitat restoration; and the development of a primitive beach camping area.

A consultation on Oregon’s Integrated Predator Damage Management Program was completed in 2001. The objective of this program is to assist in recovery of the western snowy plover in Oregon by improving western snowy plover nesting and fledging success, through 1) expanding assessment efforts to all western snowy plover breeding and nesting locations to determine predator species responsible for nest, chick and adult predation; and 2) reducing the local predator populations where feasible and where the predator species or individual is known. The consultation 125
calls for a variety of lethal and non-lethal methods to be used by APHIS-WS personnel to control the predator population.

The Oregon Parks and Recreation Department has been working with various cooperating agencies to develop a Habitat Conservation Plan for Oregon beaches.

The Oregon Parks and Recreation Department is responsible for various management activities for most of Oregon's coast, including recreation management, general beach management, and the management of natural resources. In addition, the Oregon Parks and Recreation Department is responsible for issuing various permits along the Oregon coast. Some of these activities may result in "take" of or harm to the snowy plover. A draft version of the Habitat Conservation Plan was distributed to the public in January 2004. The Oregon Parks and Recreation Department conducted public meetings in seven coastal communities to solicit public comment. The area covered under the HCP includes the portions of the ocean shore along the Oregon coast that extend between the mouth of the Columbia River South Jetty on the north and the California/Oregon border on the south (approximately 230 miles of beach). In addition, specific portions of six key state parks, state natural areas, and state recreation areas are included in the covered lands to be managed for snowy plover recovery. Implementation of the plan will begin after approval and completion of the Habitat Conservation Plan and its associated documents.

In southern California, we, through our Carlsbad Fish and Wildlife Office, have worked with local jurisdictions to develop regional habitat conservation plans under section 10 of the Endangered Species Act. The Multiple Species Conservation Program addresses southwestern San Diego County, including, for example, western snowy plover breeding habitat in south San Diego Bay through the City of San Diego.

The Multiple Habitat Conservation Program addresses northwestern San Diego County. This plan provides for the conservation of western snowy plover breeding habitat and will potentially result in more management in association with a proposed preserve.

Also in San Diego County, we have been working with the Navy and the Marine Corps to avoid and minimize impacts to western snowy plovers. For example, with the assistance of our programmatic biological opinion in 1995, the Marine Corps has addressed training-related impacts on western snowy plovers and other species on 126
approximately 17 miles of coastline on Camp Pendleton. We have likewise worked with the Navy at Naval Base Coronado to develop a program to conserve western snowy plover nesting and breeding habitat and allow necessary military training. As a result of successful management on these San Diego County military installations, they support a majority of the western snowy plover population in Recovery Unit 6 (e.g., roughly 65 percent in 2006 from window survey data) while the military installations accomplish their respective training missions.

In the past, several instances were documented of western snowy plover nests being trampled by cattle belonging to the Vail and Vickers Company on Santa Rosa Island within the Channel Islands National Park, owned and managed by the National Park Service. In 1996, a lawsuit to remove cattle from Santa Rosa Island was initiated by the Environmental Defense Center, Santa Barbara, on behalf of the National Park Conservation Association. It was initiated under the authority of the Clean Water Act and the Endangered Species Act, based on concerns about management of livestock by the National Park Service and associated impacts to water quality and sensitive plant and animal species. As a result of a lawsuit settlement, all cattle were removed from Santa Rosa Island in early 1998.

7. Regulatory Protection and Policies of Local Governments Local governments regulate municipal land uses through development of local land use plans, general plans, comprehensive plans, and zoning policies. On April 21, 1998, we requested that county and coastal city planners within the states of Washington, Oregon, and California complete land-use management surveys regarding the western snowy plover. We sent surveys to 91 State, county, or coastal city planners and received responses from 37 percent of the recipients.

Approximately 50 percent of the respondents were aware that western snowy plover habitats occur within their jurisdictions. However, only about one-third knew whether sandy beach and other habitats within their jurisdictions provided breeding and/or wintering habitat for western snowy plovers. Many general plans, coastal zone programs, and comprehensive plans prepared by local governments contain land use designations that are protective of western snowy plover habitats (e.g., parkland, open space, and conservation designations for sandy beach). However, allowable uses in or adjacent to these zones, such as development (e.g., seawalls, recreational 127
facilities, single-family homes), recreation and public access, could cause direct or indirect threats to breeding or wintering western snowy plovers.

Whereas 43 percent of the respondents include regulatory policies that protect western snowy plover habitat (e.g., sandy beach) in their general plans, local coastal programs or comprehensive plans, only 8 percent have developed regulatory policies specifically to protect the western snowy plover. These respondents included the City of Half Moon Bay, California, and Coos and Curry Counties, Oregon. Only 23 percent of the respondents specifically explain the threatened status of the western snowy plover, identify western snowy plover breeding/wintering locations, or specify shorebird nesting/roosting habitats as environmentally sensitive habitat areas in their jurisdictions. About 50 percent of the respondents indicated they either (1) have approved development within or adjacent to sandy beach or other habitats used by the western snowy plover, or (2) did not know whether such development had been approved by their agency. About half of these same respondents could provide some information on the number of permits authorized, area or linear distance affected, percentage of development types (e.g., housing, recreational) permitted, and permit conditions.

Based on these responses, it seems that specific locations of, and protective measures for, western snowy plover breeding and/or wintering locations are not included in most of the existing general plans, comprehensive plans, local coastal programs, or their implementing ordinances. Also, to better assess cumulative impacts, these responses indicate a need for a better tracking method regarding development projects approved within and adjacent to western snowy plover habitat.

8. Interagency Coordination
Each of the six recovery units for the western snowy plover is represented by a working group which meets at least once a year to coordinate western snowy plover recovery efforts. The working groups have provided a forum for the participation of affected Federal and State agencies and others in discussion, implementation, and adjustment of recovery efforts. Items addressed include research and monitoring needs, predator control, recreation management, habitat restoration, public outreach and law enforcement. In addition, a joint meeting of all six working groups is held 128
annually. This group, consisting of beach managers, researchers, and outreach staff, meet to discuss range-wide issues (within the United States), to coordinate recovery actions, to learn from the experience of others, and to share information and research.

Attendees have included local, State, and Federal agency staff, non-governmental organizations, consulting firms, private citizens, and volunteers.

The recovery unit working groups vary somewhat in organizational structure depending on major local issues, patterns of land ownership within the area, and specific agencies responsible for management. For example, the Oregon/Washington working group is composed of several subcommittees, including Outreach, Media, Predator Control, Research, Law Enforcement, and Recovery Plan Implementation.

They facilitate funding partnerships for monitoring and management programs, thus promoting the best use and leveraging of limited funds. They also act as the main forum for discussing and tracking the status and trends of the snowy plover population. The subcommittees have worked on or supported a variety of cooperative projects, such as monitoring of yearly reproductive success, predator control, and outreach materials. Products developed by the Outreach subcommittee include an outreach plan for Oregon/Washington and “Share the Beach” bookmarks, table tents, dog leashes, brochures, interpretive signs, and coloring books. The Media subcommittee is producing a media outreach CD for distribution to various media outlets and inter-agency press releases. The Predator Control subcommittee approved a predator management plan for Oregon, which first went into effect in 2002. The purpose of the Research subcommittee is to identify research and monitoring priorities, establish criteria for setting priorities, review proposed projects, and address funding mechanisms. The Law Enforcement subcommittee focuses on improving compliance with rules and regulations in plover nesting areas and the Recovery Plan Implementation subcommittee is working on guidance that would assist in “stepping down” the recovery plan for Oregon and eventually Washington.

In 1998, an interagency effort in Oregon produced a slide show and portable display to educate beach visitors about western snowy plover conservation. Outdoor education specialists and/or western snowy plover biologists from the U.S. Bureau of Land Management, U.S. Forest Service, Oregon Department of Fish and Wildlife, Oregon Parks and Recreation Department, and U.S. Fish and Wildlife Service participated in this effort. The show provides basic information about the western 129
snowy plover, the reasons for its decline, and actions needed for its recovery, emphasizing the contribution that beach visitors can make. 130
131
II. RECOVERY
A. RECOVERY STRATEGY
The recovery strategy for the Pacific coast population of the western snowy plover (western snowy plover) includes three major components: 1) increase population numbers distributed across the range of the Pacific coast population of the western snowy plover; 2) ameliorate or eliminate threats by conducting intensive ongoing management for the species and its habitat, and developing mechanisms to ensure management in perpetuity; and 3) monitor western snowy plover populations and threats to determine success of recovery actions and to refine management actions.

Developing and implementing intensive adaptive management actions, ensuring that management will continue in perpetuity, and monitoring to refine management actions, are all necessary to achieve the targeted population increases across the range. These three major components of the recovery strategy each include many actions and multiple partners that are described in further detail below.

1. Recovery Strategy Components
The following recovery strategy components will guide future recovery efforts for the U.S. Pacific coast population of the western snowy plover. a. Population increases should be distributed across the western snowy plover’s Pacific coast range.

A key component of recovering western snowy plovers is to ensure that population increases are distributed throughout the species’ Pacific coast range. In order to achieve this, management goals (Appendix B) and needed management actions (Appendix C) have been determined for 155 sites distributed along the coasts of southern Washington, Oregon, and California. Additionally, the population’s range has been divided into six recovery units (see discussion below) with population goals established for each recovery unit. The six recovery units correspond to regions of the U.S. Pacific coast and to the six subpopulations used in the Population Viability Analysis for the Pacific coast Snowy Plovers (Appendix D). In the population viability analysis, the Pacific coast population of the western snowy plover is treated 132
as a metapopulation, defined as a set of subpopulations among which there is limited dispersal.

The population viability analysis assumes dispersal among subpopulations is limited; however, even limited dispersal among subpopulations is important to species survival and recovery. Dispersal of the population across its breeding range helps to counterbalance catastrophes, such as extreme climatic events, oil spills, or disease that might depress regional survival and/or productivity. Maintaining robust, well- distributed subpopulations should reduce variance in survival and productivity of the Pacific coast population of the western snowy plover as a whole, facilitate interchange of genetic material between subpopulations, and promote recolonization of any sites that experience declines or local extirpations due to low productivity and/or temporary habitat loss.

This recovery plan and the population viability analysis (Appendix D) consider the U.S. Pacific coast population of the western snowy plover to be a single management entity, and population goals and objectives are based on that premise. No portion of the Pacific coast population of the western snowy plover appears to function as a distinct population segment. The Recovery Team therefore recommends that no State, geographic region, or subpopulation of the Pacific coast population of the western snowy plover be considered for delisting separately from the others. b. Remove or reduce threats by conducting intensive ongoing management for the species and its habitat, and develop mechanisms to ensure management in perpetuity to prevent a reversal of population increases following delisting under the Endangered Species Act.

Management consists of multiple components, including identifying actions to ameliorate or eliminate threats, developing mechanisms to ensure management in perpetuity, continuing outreach and education to provide information to the public, partners, and stakeholders on recovery needs and opportunities, and developing of partnerships among Federal, State, and local agencies and groups to develop and implement effective management. Management actions for the western snowy plover are described in the recovery action outline and in Appendix C. These management actions are necessary to eliminate or ameliorate threats to the western snowy plover, 133
including loss, degradation, and alteration of habitat; disease, predation; and other manmade factors including disturbance of breeding and wintering birds, contaminants, and oil spills.

In addition to specific management recommendations to ameliorate or eliminate threats, the recovery action outline and recovery strategy for the western snowy plover include several recovery actions to develop mechanisms to ensure that management actions continue in perpetuity to ensure that threats remain neutralized.

These include establishing working groups and developing participation plans for each recovery unit; ensuring sufficient U.S. Fish and Wildlife Service staff to coordinate recovery of the Pacific coast population of the western snowy plover; developing and implementing management plans for publicly owned lands; assisting local governments and private land owners in developing habitat conservation plans, developing land use protection measures, and developing landowner agreements; and acquiring habitat where necessary. A key component of these efforts includes education and outreach to inform partners and the public about recovery needs and opportunities for the western snowy plover. Actions for outreach are included in the recovery action outline, and the Information and Education Plan (Appendix K) provides greater detail on implementing these outreach and education actions.

Participation of many different groups will be essential to achieve both short-term and long-term management for the western snowy plover and its habitat. The roles of various groups, potential conservation tools and funding available, and the Recovery Team’s vision for participation and coordination of partners are further described below.
c. Annual monitoring of western snowy plover subpopulations and reproductive success, and monitoring of threats and effects of management actions in reducing threats, is essential for adaptive management and to determine the success of recovery efforts.

The recovery action outline describes monitoring for breeding, wintering, and migration areas both to determine whether population numbers and survival of western snowy plovers is increasing and whether threats continue to limit population increases. Additional research actions are also recommended to study certain threats 134
and develop management techniques and monitoring methods. Results from research and monitoring efforts will be used to develop, refine, and improve management of western snowy plovers and their habitat. Monitoring of demographic characteristics will be necessary to demonstrate that population goals in the recovery criteria are being achieved. Monitoring of threats and effects of management actions in reducing those threats also is essential in demonstrating progress toward recovery and ultimately will assist in threats analyses necessary to make a delisting determination.

2. Roles of Federal, State, Local, and Private Sectors a. Role of Federal Lands
Federal lands administered by the U.S. Fish and Wildlife Service, National Park Service, U.S. Forest Service, U.S. Bureau of Land Management, the National Marine Sanctuary Program, U.S. Marine Corps, and the U.S. Departments of the Army (including Corps of Engineers), Navy, and Air Force are extremely important to the conservation of the western snowy plover. In California, breeding occurs on National Wildlife Refuge lands, Department of Defense lands, Bureau of Land Management lands, and National Park Service lands. In Oregon, the major Federal landowners are the U.S. Forest Service and Bureau of Land Management, although the State also has jurisdiction over much of the Federally owned area (from mean high tide to the vegetation line) through a recreational easement (E.Y. Zielinski and R.W. Williams in litt. 1999). In Washington, the breeding area at Leadbetter Point is within a National Wildlife Refuge.

Under section 7(a)(1) of the Endangered Species Act, Federal agencies are required to actively promote the conservation of listed species. The western snowy plover cannot be recovered simply through general habitat protection or complying with required section 7(a)(2) consultations. The western snowy plover must be actively monitored and managed for the purpose of recovery or its population size will decline. Federal agencies alone cannot assure recovery of the western snowy plover, but should have a leading role in monitoring and management efforts to assure survival and recovery of this species. Some Federal lands contain large areas of contiguous habitat, including adjacent inland areas that are easier to manage for conservation of natural resources than fragmented, linear strips of land that may be 135
owned by states, counties, cities, and private landowners. Protection of western snowy plovers and their habitat on Federal lands is important not only because of the direct benefits to plovers that use these areas, but also because plover protection programs on Federal lands frequently utilize state-of-the art management measures and therefore serve as examples to non-Federal landowners. The Federal Government also should take the lead in addressing the sensitive issue of predator control.
b. Role of State Lands
State lands administered by the California Department of Parks and Recreation, California Department of Fish and Game, Oregon Department of Fish and Wildlife, Oregon Parks and Recreation Department, Washington Department of Fish and Wildlife, Washington State Parks and Recreation Commission, and Washington Department of Natural Resources play an important role in conservation of western snowy plovers and their habitats. Intensive management for western snowy plovers occurs at a number of State-owned plover habitat areas. The western snowy plover cannot be preserved simply through general habitat protection. Western snowy plovers must be actively monitored and managed to achieve recovery goals on State lands or their population size will decline.
c. Roles of State and Local Governments
State and local government agencies, including state planning agencies and city and county planning and community resources departments, have the primary responsibility for overseeing land uses within their jurisdictions. Therefore, their involvement in future recovery planning and implementing processes is critical. All Appendix B locations should be identified as environmentally sensitive habitat areas requiring protective measures for the western snowy plover in state and local planning documents and zoning designations. Local coastal programs should be amended to include these areas. To facilitate this effort, Federal and State agencies managing western snowy plover habitat should provide technical assistance and information to local governments (see Actions 3.1.6, 3.1.7 and 5.2). We can provide detailed maps of current western snowy plover breeding and/or wintering locations; these maps will be updated periodically as needed.
136
d. Role of Municipal Lands
Regional, county, and city lands, including regional and municipal park districts, also serve a role in conserving breeding and wintering habitats for western snowy plovers.

Because these areas frequently receive heavy pedestrian and recreational use, local jurisdictions with active public outreach programs can reach a large segment of the coastal community regarding the plover’s status and habitat needs. e. Role of Private Lands
Conservation efforts on private lands are needed for the survival and recovery of many listed and other sensitive species. Private landowners can also make important contributions to western snowy plover conservation through facilitating or allowing the monitoring of western snowy plover populations on their land and implementing protective measures.

3. Conservation Tools and Strategies
There are numerous conservation tools and strategies available to Federal, State, municipal, and private landowners interested in western snowy plover protection and recovery. Appendix H includes a summary of conservation tools and strategies that may be adopted by landowners, nonprofit organizations, and regulatory agencies to protect western snowy plover habitat.

4. Funding Sources
Appendix I includes a summary of some potential sources of funds for implementation of recovery actions for the western snowy plover. This list is not intended to be exhaustive, however, and other funding opportunities may also be available.

An essential mechanism for recovery of the western snowy plover is the development and implementation of participation plans for each of the six recovery units (see Action 3.1.2). A key element of these participation plans is the long-term 137
commitment by participating agencies to seek annual, ongoing funding for western snowy plover management and monitoring activities so that funding within agency budgets can be secured.

In many areas a significant portion of western snowy plover conservation resources are expended in efforts to minimize the adverse impacts of recreation. Often, the primary objective of signs, ropes, on-site interpretation, and enforcement is to manage the behavior of beach-goers such that impacts to western snowy plovers are reduced as much as possible. In areas that have suffered extensive habitat loss or degradation, such recreation management activities are an extremely high priority in order to protect the western snowy plovers using the limited habitat that remains. For some beach managers, much of the funding and staff time expended on recreation management in and near western snowy plover habitat comes from resources targeted for threatened and endangered species recovery. In absence of the need to coordinate and pay for recreation management activities, more of these limited conservation dollars and staff resources could be directed toward western snowy plover management actions such as biological monitoring, habitat restoration, and predation control.

This situation is unique in the experience of many resource biologists. More typically, avoidance, minimization, and mitigation measures are integral components of projects or programs that entail adverse impacts to sensitive resources, and the costs of these activities are regarded as part of the overall cost of the project or program. Applying this traditional construct to recreation projects and programs could significantly promote western snowy plover recovery in several ways. First, it would require impacts to western snowy plovers to be considered up front when planning beach access or other recreation projects. Second, it would encourage impact avoidance and minimization since such measures are often less expensive than mitigation. Third, it would promote involvement of recreation professionals in designing and implementing recreation management measures. And fourth, it would eliminate or reduce the diversion of biological resource management funds toward recreation management activities, thus enabling more of those dollars to be spent on western snowy plover recovery actions.
138

5. Coordination, Participation, and Working Groups
We strongly believe that a collaborative stewardship approach to the proactive management of listed species involving government agencies (Federal, State, and local) and the private sector is critical to achieving the ultimate goal of recovery of listed species under the Endangered Species Act. An essential mechanism to achieve recovery of the western snowy plover is the formation and maintenance of working groups for each of the six recovery units (Appendix A), (see Action 3.1.1).

Representation from the full range of Federal, State, local, and private landowners and other parties who have a stake in western snowy plover conservation within each of these six recovery units is needed to advance the recovery actions recommended in this recovery plan. Working group membership should include land managers, environmental groups, user groups, and groups involved in conservation projects (including local chapters such as the National Audubon Society, Sierra Club, Native Plant Society, Americorps, California Conservation Corps, Boy Scouts, Surfrider Foundation, and other recreational use groups). These groups can provide large networks of volunteers who can be mobilized to assist public resource agencies in the implementation of management measures for protection and recovery of the western snowy plover.

Working groups for each of the six recovery units currently exist and convene annually for regional and rangewide meetings. Through evaluation, communication, and coordination, members of each of the six working groups should manage the western snowy plover population and monitor progress towards recovery. They should produce annual reports on population monitoring and the effectiveness of management activities for the working group and our Arcata Fish and Wildlife Office. Each of the six working groups should prepare a participation plan, thereby formalizing recovery implementation efforts and the intentions of responsible agencies to seek ongoing, annual funding for recovery implementation. The Recovery Coordinator should coordinate and communicate with each recovery unit to support recovery efforts and assure implementation of the recovery plan (see Actions

3.1 through 3.4, 6, and 7). The Recovery Coordinator also should coordinate with other western snowy plover survey efforts and assessments throughout the west and throughout North America. Coordination with these other efforts may provide valuable information on the status and distribution of the western snowy plover, as 139
well as valuable information on management actions that may benefit the Pacific coast population of the western snowy plover. A coordinated international conservation program with Mexico also should be established to protect western snowy plover populations and their habitat in that country (see Action 8).

B. RECOVERY UNITS
The Pacific coast population of the western snowy plover has been divided into six recovery units (Appendix A, Figures A-1 through A-7). Establishing recovery units with specific recovery goals for each recovery unit will assist in meeting the objective of ensuring that population increases are distributed throughout the western snowy plover’s Pacific coast range. A recovery unit is a special unit of a listed species that is geographically or otherwise identifiable and is necessary to the survival and recovery of the entire listed entity. Recovery units are individually necessary to conserve genetic robustness, demographic robustness, important life history stages, or other features for long-term sustainability of the entire listed species. However, recovery units are not listed as separate entities and cannot be delisted individually.

Each recovery unit must be recovered before the species can be delisted.

The resilience to extinction of a widespread species can be negated if the species is subjected to a new stress over a large area (Raup 1991:122, 182). For the western snowy plover the primary stresses that led to the listing of the species were the loss of habitat due to encroachment of European beachgrass and urban development. As a consequence of such widespread habitat loss and the subsequent reduction in the range and vigor of the species, the western snowy plover is now more vulnerable to environmental fluctuations and catastrophes that the species would otherwise be able to tolerate. Chance events such as oil and contaminant spills, windstorms, and continued habitat loss from European beachgrass expansion, described earlier in this plan, could now cause or facilitate the extirpation of the entire listed species or one or more of the breeding populations.

The recovery unit approach in this recovery plan addresses this risk to the long-term survival and recovery of the western snowy plover by employing two widely recognized and scientifically accepted goals for promoting viable populations of listed species: (1) creation or maintenance of multiple populations so that a single or 140
series of catastrophic events cannot destroy the whole listed species; and (2) increasing the size of each population in the respective recovery unit to a level where the threats of genetic, demographic, and normal environmental uncertainties are diminished (Mangel and Tier 1994; National Research Council 1995:91; Tear et al. 1993; Meffe and Carroll 1994:192).

In general, the larger the number of populations and the larger the size of each population, the lower the probability of extinction (Raup 1991:182; Meffe and Carroll 1994:190). This basic principle of redundancy applies to the western snowy plover.

By maintaining viable populations at the breeding locations within multiple recovery units, the threats represented by a fluctuating environment are alleviated and the species has a greater likelihood of achieving long-term survival and recovery.

Conversely, loss of one or more important breeding locations within a recovery unit could result in an appreciable increase in the risk that the entire listed species may not survive and recover. Because western snowy plovers tend to exhibit site fidelity, migration to new nesting sites could increase stress to breeding birds and reduce nesting success.

Therefore, when evaluating the potential impact of land management actions that may affect the western snowy plover, we will consider whether a significant loss of western snowy plover breeding or wintering habitat in one recovery unit --without adequate compensation alleviating the impacts of that loss-- would adversely affect the viability of the population in that recovery unit as well as the long-term viability of populations in other recovery units.

Several aspects of the biology and life history of the western snowy plover indicate that designation of recovery units is necessary to ensure the long term health and sustainability of the western snowy plover. A portion of the Pacific coast population of western snowy plovers do not migrate up or down the coast and are year round residents. Additionally, the majority of western snowy plovers that do migrate are site-faithful, returning to the same breeding areas in subsequent breeding seasons (Warriner et al. 1986, Stenzel et al. 1994). Western snowy plovers occasionally nest in exactly the same location as the previous year (Warriner et al. 1986). These two features indicate that the Pacific coast population of western snowy plover likely exhibits subpopulation and metapopulation structure (see also Appendix D). 141
Designation of separate recovery units across the range will ensure that metapopulation dynamics can be maintained for the species.

The area covered by the six recovery units encompasses all the known breeding and wintering sites for the Pacific coast population of the western snowy plover. In addition to exhibiting site fidelity to breeding locations, western snowy plovers also exhibit fidelity to wintering locations. In contrast to many migratory birds, winter migration of the Pacific coast population of western snowy plovers is not uni- directional. Western snowy plovers may move both north and south along the coast from breeding locations. Nesting birds from Oregon have wintered as far south as Monterey Bay, California, while birds from Monterey Bay in central California have wintered north to Bandon, Oregon and south to Laguna Ojo de Liebre in Baja California, Mexico (Page et al. 1995a). Nesting birds from San Diego County in southern California have wintered north to Vandenberg Air Force Base in Santa Barbara County and south to Baja California (Powell et al. 1995, 1996, 1997).

Designation of separate recovery units, each essential to the recovery of the western snowy plover, will ensure that wintering and migratory habitat is distributed across the western snowy plover’s Pacific coast range and is protected and managed to maximize western snowy plover population survival.

The six recovery units for the Pacific coast population of the western snowy plover are: (1)Washington and Oregon; (2) Del Norte to Mendocino Counties, California; (3) San Francisco Bay, California; (4) Sonoma to Monterey Counties, California; (5) San Luis Obispo to Ventura Counties, California; and (6) Los Angeles to San Diego Counties, California. These recovery units were designated partly based on gaps in distribution of western snowy plover breeding and wintering locations, and on gaps in available habitat along the coast. For example, a significant portion of the coast of Sonoma County and southern Mendocino County is rocky and composed of steep bluffs lacking beach, dune, or estuary habitat suitable for the western snowy plover.

This area constitutes a gap in the distribution of breeding and wintering locations between recovery units 2 and 4. This situation is repeated along the coast of Monterey County, where a gap in western snowy plover locations and suitable habitat occurs between recovery units 4 and 5. Smaller gaps also occur between recovery units 1 and 2, and between recovery units 5 and 6. Recovery unit 3 is unique and has 142
been designated as a separate recovery unit because much of the habitat in the San Francisco Bay area consists of salt ponds and salt pond levees.

The six recovery units designated for the western snowy plover also vary significantly in numbers of breeding western snowy plovers. Recovery unit 5 supports the greatest number of western snowy plovers, approximately half of the U.S. population, and has the greatest amount of available suitable habitat. Recovery units 4 and 6 support, or have the potential to support, a lesser number of western snowy plovers, collectively about a third of the population. The population in Recovery Unit 3 is relatively lower but has potential to increase with intensive management of salt pond habitat. Recovery units 1 and 2 also support relatively low numbers of western snowy plovers, probably due to suitable habitat being lesser in extent and more widely separated, but represent about half of the geographic range of the Pacific coast population of western snowy plovers within the United States and provide essential wintering, migratory, and breeding habitats.

Collectively, recovery of western snowy plovers within each of the six recovery units is necessary to maintain metapopulation dynamics, ensure protection and appropriate management of wintering and migratory habitat, and ensure the long term health and sustainability of the Pacific Coast population of western snowy plovers across its current range.

C. RECOVERY GOALS AND OBJECTIVES
The goal of this recovery plan is to ensure the long-term viability of the Pacific coast western snowy plover population so that this population can be removed from the Federal list of endangered and threatened species. The specific objectives to achieve this goal are the major components of the recovery strategy described above:
1) Increase population numbers distributed across the range of the Pacific coast population of the western snowy plover;
2) Conduct intensive ongoing management for the species and its habitat and develop mechanisms to ensure management in perpetuity; and
143
3) Monitor western snowy plover populations and threats to determine success of recovery actions and refine management actions.

D. RECOVERY CRITERIA
Recovery criteria for the Pacific coast population of the western snowy plover include numeric subpopulation targets, reproductive productivity targets, and establishment of management actions. Under each of these three major recovery criteria are additional subcriteria that must be achieved in order to progress toward the major criteria or that must be achieved in order to determine whether the major criteria are being met. Subcriteria include completing development and implementation of population, demographic and threat monitoring programs, incorporating specific management actions into participation and management plans, and completing research actions necessary to refine management actions.

Recovery criteria in this recovery plan are necessarily preliminary and will need periodic reassessment because additional data upon which to base decisions about western snowy plover recovery are needed (i.e., effective predator management techniques, effective restoration techniques, improved monitoring techniques, additional demographic information for some subpopulations). Research actions, monitoring programs, and periodic recovery implementation review are included as recovery actions in order to obtain this information. The completion of many of these actions have been incorporated into recovery criteria in order to ensure that new information is incorporated into recovery implementation decisions.

The recovery criteria recommend that the Pacific Coast population of the western snowy plover be maintained at 3,000 breeding birds. This population increase to 3,000 breeding individuals could occur within 25 years with intensive management of breeding and wintering sites (see Appendix D. Population Viability Analysis for Pacific Coast Snowy Plovers). This population level must be maintained for at least ten years. In addition, average annual productivity of at least one (1.0) fledged chick per male in each recovery unit must be maintained in the last 5 years prior to delisting. Forty years may be required to achieve these demographic components of the recovery criteria, assuming that mechanisms to assure long-term protection and 144
management of breeding, wintering, and migration areas necessary to maintain the subpopulation sizes and average productivity have been developed and are in place.

The Pacific coast population of the western snowy plover will be considered for delisting when the following criteria have been met:

Criterion 1. Monitoring shows that an average of 3,000 breeding adults distributed among 6 recovery units as specified below have been maintained for a minimum of 10 years:

Recovery Unit Subpopulation Size

1. Washington and Oregon 250 breeding adults

2. Del Norte to Mendocino 150 breeding adults Counties, California

3. San Francisco Bay, California 500 breeding adults

4. Sonoma to Monterey Counties, 400 breeding adults California

5. San Luis Obispo to Ventura 1,200 breeding adults
Counties, California

6. Los Angeles to San Diego Counties, 500 breeding adults California
Subpopulation sizes represent the best professional judgment of the Western Snowy Plover Recovery Team’s technical subteam. Numbers are based on a site-by-site evaluation of historical records, recent surveys, and future potential (assuming dedicated, proactive management at breeding and wintering locations). Collectively, these numbers represent an approximately 70 percent increase in the Pacific coast population size from the time of listing. On a cumulative range-wide basis the recovery criteria are approximately 83 percent of the total of the “Management Goal Breeding Numbers” identified in Appendices B and C, which represent site-specific target populations under an intensive management scheme. The recovery criteria for population size and distribution for the Pacific coast population of the western snowy plover represent only a portion of its historical abundance and distribution. 145
To reach these subpopulation sizes will require proactive management to attain a level of productivity that will allow the population to grow. The population viability analysis (Appendix D) suggests that reproductive success between 1.2 to 1.3 fledglings per male per year, with adult survival of 76 percent and juvenile survival of 50 percent, provides a 57 to 82 percent probability of reaching a population of 3,000 western snowy plovers within 25 years. Enhancing productivity is critical to population growth. Once the population size criterion is met, a lower rate of productivity can sustain the population.
1a. A program is developed and implemented to monitor the western snowy plover breeding population and wintering locations (see Actions 1.1 and 1.2) to determine whether recovery unit subpopulation criteria are being achieved.

The monitoring program must include monitoring of population size and distribution, survival, and productivity. Monitoring population size and distribution are necessary as a means of measuring whether the recovery criterion is being met. Monitoring demographic characteristics such as survival and productivity also will be necessary to determine population trends and progress toward achieving the recovery criterion.

The monitoring program should also assess whether management goals for breeding and wintering sites listed in Appendix B are being achieved. Collectively, the breeding management goal numbers are about 20 percent higher than the recovery criteria subpopulation sizes. Monitoring of individual sites will assist in determining the effectiveness of management actions and whether any refinements are necessary.

Monitoring of wintering sites will assist in indicating whether survival of western snowy plovers is sufficient to make progress toward meeting breeding population size criteria.

When the species has recovered sufficiently to be delisted, the ongoing program of monitoring actions should be integrated into a post-delisting monitoring plan to cover a minimum of 5 years after delisting and ensure ongoing recovery and effectiveness of management actions. This monitoring plan should be developed and ready for implementation before delisting.
146
1b. A program is developed and implemented to monitor the site-specific threats identified in Appendix C (Action 1.3) and monitoring results are used to refine site-specific management actions identified in Appendix C.

In conjunction with monitoring of breeding subpopulation sizes and distribution and demographic characteristics, threats at each breeding and wintering site must be monitored in order to determine whether management actions are effective in increasing western snowy plover survival and reproduction. If threats continue limiting population increases, or additional threats are identified, management actions recommended in Appendix C may require modification.
1c. Management activities identified in Appendix C that are necessary to ameliorate threats and achieve increases in reproductive success, survival, and overall population size are incorporated into participation and management plans developed and implemented under Criterion 3.

Appendix C provides location-specific summaries of current management activities at western snowy plover breeding and wintering sites based on: 1) responses by public land managers and private conservation organizations to a survey prepared by the Recovery Team on western snowy plover management and beach use; and 2) supplemental information from the Recovery Team and from our field office staff.

Appendix C also identifies additional management activities needed at each site to ameliorate threats and achieve management goals. These management recommendations are intended to provide preliminary guidance but additional management needs likely will be identified through monitoring, research, and site- specific experience.
1d. Research actions (Action 4) are completed and incorporated into management and participation plans and into monitoring plans.

Several research needs identified under Action 4 are necessary to refine and improve management activities for the western snowy plover and also to improve monitoring of western snowy plover population sizes, demographics, and threats. Improving and refining management actions will increase the effectiveness of management actions in increasing population numbers, survivorship, and productivity. Improved monitoring 147
techniques are needed to ensure that monitoring efforts are adequate to determine whether recovery actions are successful and recovery criteria are being met.

Criterion 2. A yearly average productivity of at least one fledged chick per male has been maintained in each recovery unit in the last 5 years prior to delisting.

From currently available data, it is estimated that males must average one fledged young annually for population equilibrium (see Appendix D). Higher rates of productivity will be necessary to reach the target population size of 3,000 breeding adults. After this population size is achieved and maintained for a minimum of 10 years, a lower rate of productivity of one fledged chick per male will be necessary to maintain the population size at an average of 3,000 breeding adults. Monitoring programs developed and implemented under criteria 1a and 1b should continue throughout this period. We also assume that management designed to ameliorate threats (criteria 1c and 3) will continue through this period and after delisting.

Criterion 3. Mechanisms have been developed and are in place to assure long- term protection and management of breeding, wintering, and migration areas listed in Appendix B to maintain the subpopulation sizes and average productivity specified in Criteria 1 and 2.

Development of mechanisms to ensure long-term management and protection of western snowy plovers and their habitat are listed under Action 3, which outlines the recovery actions recommended to meet these recovery criteria. The recovery action outline section describes each action in detail. The recovery action outline lists all subactions necessary to fulfill the main recovery action. It also represents a prioritization of measures to be implemented. Completion of these actions will ensure that threats to western snowy plovers and their habitat are ameliorated and that management will continue after delisting to prevent a reversal of population increases.
3a. Working groups for each of the six recovery units are established.

Action 3.1 recommends the establishment of working groups for each recovery unit.

Working groups should be diverse and include representatives from Federal, State, 148
local, and private sectors. At present working groups are in existence for all recovery units, and should continue to be maintained and meet regularly. The roles of the working groups are to coordinate and facilitate recovery efforts within each recovery unit, assess population trends, and carry out outreach activities. 3b. A participation plan for each recovery unit working group has been developed and implemented.

Each working group is tasked with developing a participation plan that delineates and prioritizes recovery activities within each recovery unit and for each location identified in Appendix B. These plans should identify the roles and responsibilities of each member of the working group and their commitments to carry out identified recovery actions.
3c. Management plans for all Federal and State lands identified in Appendix C have been developed and implemented.

Appendix C identifies the landowners of western snowy plover wintering and breeding sites. Many of the sites are owned or managed by Federal or State agencies.

Development and implementation of management plans that incorporate the management goals and recommendations in Appendix C for all these sites are necessary to ensure that population goals are reached, threats ameliorated, and long- term protection and management of western snowy plovers and their habitat are in place.
3d. Mechanisms to protect and manage western snowy plover breeding and wintering sites identified in Appendices B and C are in place for all areas owned or managed by local governments or private landowners.

Appendix C also identifies many western snowy plover breeding and wintering locations that are owned or managed by local governments, private conservation organizations, or private landowners. These lands also require protection and management to ensure that population goals are reached, threats ameliorated, and long-term protection and management of western snowy plovers and their habitat are in place. Because of the diverse ownership and management of these lands, many 149
different mechanisms may be used to ensure protection and management of these locations. These mechanisms are further described in the recovery action outline and Appendices H and I.
3e. Public information and education programs are developed and implemented.

Outreach is a major component of developing and putting in place mechanisms to assure long-term protection and management of breeding, wintering, and migration areas listed in Appendix B. Outreach efforts will be needed to solicit participation of the many Federal, State, local, and private groups in recovery efforts and notify groups and individuals of recovery opportunities and incentives for the western snowy plover. Outreach efforts also must be used as a component of management of western snowy plovers and their habitats. These efforts will include informing the public and gaining their support for measures intended to protect western snowy plovers.

E. RELATIONSHIP OF RECOVERY ACTIONS AND CRITERIA TO

THREATS
The goal of this recovery plan is to ensure the long-term viability of the Pacific coast population of western snowy plovers so that they can be removed from the Federal list of endangered and threatened species. The delisting process requires demonstrating that threats to the western snowy plover have been reduced or eliminated such that the species survival in the wild is assured. Table 8 lists the threats to the western snowy plover that have been identified during and since the listing process and indicates the actions and recovery criteria in the recovery plan that address each threat.

The western snowy plover faces multiple threats throughout its Pacific coast range.

Major threats to the western snowy plover include habitat destruction and modification and lack of habitat protection mechanisms (listing factors A and D), disease or predation (listing factor C), and manmade factors that primarily result in disturbance or mortality of breeding birds (listing factor E). Effects of research on western snowy plovers (listing factor B) is also a threat but is comparatively minor 150
and easily addressed through permitting processes. Many of the threats to western snowy plovers are interrelated or have complex interactions with each other. For example, coastal development that destroys or modifies habitat (listing factor A) also results in increased disturbance from recreational activities (listing factor E) and in increased predator populations (listing factor C). Recovery actions and criteria therefore may address multiple threats.

The majority of threats to the western snowy plover, other than habitat destruction or modification, affect the western snowy plover’s productivity (breeding success) and survival within otherwise suitable habitat. Criteria 1 and 2 are directed at determining whether the effects of threats on productivity and survival have been removed and expected population and productivity increases are being achieved.

Threats addressed by these recovery criteria primarily fall under listing factors B, C, and E. Reduction and elimination of these threats, and the expected increases in productivity and survival, rely primarily on developing intensive management and monitoring programs for the western snowy plover. Criterion 3 is directed at achieving the management and habitat protections necessary to reduce and eliminate threats that fall primarily under listing factors A and D, but also address threats under listing factors B, C, and E that can be eliminated or ameliorated by ensuring long- term management.
151
Table 8. Threats to the Pacific coast population of the western snowy plover and steps within the recovery plan to reduce or eliminate threats.

Factor* Threat Action Criterion
A The present of threatened destruction, modification, or curtailment of its habitat or range.

A* Encroachment of
introduced beachgrass
and nonnative
vegetation.

1.1-1.3, 2.2.1, 3.1-

3.10, 4.1.1, 5.1-5.7
1b-d,
2,
3a-e
A* Shoreline stabilization 1.1-1.3, 2.1, 3.1-3.10,

5.1-5.7
1b, 1c,
3a-e
A* Urban development
and construction

1.1-1.3, 2.1, 3.1-3.10,

5.1-5.7
1b, 1c,
3a-e
A Dredging disturbance
and tailings deposit

1.1-1.3, 2.1, 3.1-3.10,

5.1-5.7
1b, 1c,
3a-e
A* Sand mining 1.1-1.3, 2.1, 2.2.2,

3.1-3.10, 5.1-5.7
3a-e
A Beach nourishment
with inappropriate
design and/or sand
type

1.1-1.3, 2.2.3, 3.1-

3.10, 5.1-5.7
3a-e
A Driftwood removal 1.1-1.3, 2.3.4, 3.1-

3.10, 5.1-5.7
1b, 1c,
2 3a-e
A Beach fires and
camping

1.1-1.3, 2.3.3, 3.1-

3.10, 5.1-5.7
1b, 1c,
2 3a-e
A Water course
diversion,
impoundment, or
stabilization

1.1-1.3, 3.1-3.10, 5.1-

5.7 1b, 1c,
3a-e
Factor* Threat Action Criterion
152
A Habitat conversion for
other species

1.1-1.3, 3.1-3.10, 5.1-

5.7 1d,
3a-e
A Operation of salt
ponds

1.1-1.3, 3.1-3.10, 5.1-

5.7 1b, 1c,
3a-e
B Overutilization for commercial, recreational, scientific or educational purposes.

B* Egg collecting 1.1-1.3, 2.3.8 none, 1c
B Studying and
monitoring plovers

1.4, 1.5, 3.1-3.2, 4.3 1a-d
2 B Banding 4.6 1a-d
C Disease or predation.

C* Introduced nonnative
predators

1.1-1.3, 2.4, 4.2, 3.1-

3.10, 5.1-5.7
1b, 1c,
2 3a-e
C Increased populations
of native predators
due to human
influences

1.1-1.3, 2.4, 4.2,3.1-

3.10, 5.1-5.7
1b, 1c, 1d,
2,
3a-e
C* Predator attractants 1.1-1.3, 2.4, 4.2, 3.1-

3.10, 5.1-5.7
1b, 1c, 1d,
2,
3a-e
C Predation by domestic
and feral cats

1.1-1.3, 2.4, 4.2, 3.1-

3.10, 5.1-5.7
1a-d,
2,
3a-e
D The inadequacy of existing regulatory mechanisms.

D* Limited habitat
protection under the
Migratory Bird Treaty
Act and State laws

2.3.8, 3.1-3.10, 5.1-

5.7 3a-e
Factor* Threat Action Criterion
153
D Conflicting beach
management methods
and mandates

1.1-1.3, 2.3.8, 3.1-

3.10, 5.1-5.7
1b, 1c,
3a-e
D* Sections 404 of Clean
Water Act and 10 of
Rivers and Harbors
Act apply to limited
amount of habitat

2.3.8, 3.1-3.10, 5.1-

5.7 1b-d
3a-e
D* Lack of protection in
Baja California,
Mexico
8 E Other natural or manmade factors affecting its continued existence.

E* Loss of nests and
habitat due to natural
events

1.1-1.3, 1.6, 2.1, 2.2,

2.3.8, 3.1-3.10, 4.4,

4.5, 4.10
1b, 1c,
3a-e
E* Disturbance by
pedestrians

1.1-1.3, 2.3.1, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2,
3a-e
E* Disturbance by dogs 1.1-1.3, 2.3.1, 2.3.2,

2.3.8, 3.1-3.10, 4.9,

5.1-5.7
1b, 1c,
2,
3a-e
E* Disturbance by
motorized vehicles

1.1-1.3, 2.3.5, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2,
3a-e
E* Disturbance by beach
cleaning

1.1-1.3, 2.3.5, 2.4.1,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2,
3a-e
E* Disturbance from
equestrian traffic

1.1-1.3, 2.3.6, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2,
3a-e
Factor* Threat Action Criterion
154
E Disturbance from
fishing activities

1.1-1.3, 2.3.3, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2 3a-e
E Disturbance by
fireworks

1.1-1.3, 2.3.3, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2,
3a-e
E Disturbance by kites
and model airplanes

1.1-1.3, 2.3.3, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2,
3a-e
E* Military exercises and
aircraft overflights

1.1-1.3, 2.3.8, 2.3.9,

3.1-3.10, 5.1-5.7
1b, 1c,
2 3a-e
E Large crowds
associated with
special events

1.1-1.3, 2.3.3, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2 3a-e
E Increased coastal
access to beaches

1.1-1.3, 2.3.1.2, 2.3.8,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2 3a-e
E Livestock grazing 1.1-1.3, 2.3.7, 2.3.8,

3.1-3.10, 5.1-5.7
1b, 1c,
3a-e
E Oil spills and
disturbance from oil
spill clean-ups

1.1-1.3, 2.5, 4.7, 5.6 1b-d
3a-e
1b, 1c,
2 3a-e
E Environmental
contaminants

1.1-1.3, 4.8, 5.6 1b-d,
3a-e
E Litter, garbage, &
debris

1.1-1.3, 2.3.8, 2.4.1,

3.1-3.10, 4.9, 5.1-5.7
1b, 1c,
2 3a-e
Factor* Threat Action Criterion
155
E Urban runoff and
impaired water quality

1.1-1.3, 2.1, 2.3.8,

3.1-3.10, 5.1-5.7
3a-e
E Management for other
special status species

1.1-1.3, 1.7, 2.6, 2.7,

2.3.3, 3.1-3.10, 4.2.2,

5.1-5.7
3a-e
* Indicates threats originally identified during the listing process. 156
157
III. NARRATIVE OUTLINE OF RECOVERY ACTIONS
1 Monitor breeding and wintering population and habitats of the Pacific coast population of the western snowy plover to determine effects of recovery actions to maximize survival and productivity. To assure the long- term viability of western snowy plover populations, their populations and breeding and wintering habitat should be monitored and managed in a systematic, ongoing fashion. Systematic, ongoing monitoring of breeding birds and wintering birds should be undertaken at the recovery-unit level to measure progress towards recovery and identify management and protection efforts that are needed. In addition to the known breeding sites, all known wintering locations (Appendix B) are considered currently important to western snowy plover conservation. These sites include both wintering locations that currently support breeding birds and locations that may potentially support nesting birds in the future. These locations also may support migrating western snowy plovers. There is a need for better information about wintering and migration sites, including spatial and temporal use patterns, feeding areas, habitat trends, and threats. Appendix C, Table C-1 identifies 147 locations where monitoring western snowy plover populations is occurring or recommended to achieve management goals.

1.1. Annually monitor western snowy plover abundance, population size, and distribution at breeding and wintering locations in each recovery unit using window surveys. Comprehensive range-wide window surveys of breeding locations and wintering locations (Appendix B) should be conducted annually to determine population trends and fluctuations, and to determine whether management goal breeding numbers (Appendix B) are being achieved. The window survey described in Appendix J (Monitoring Guidelines) should be employed as the primary index of population size to minimize the probability of double-counting birds nesting at multiple locations during the same season. Window surveys are conducted over a relatively short time period to minimize double-counting of birds that change location during the season, but may not fully account for all breeding or wintering birds. Window survey methodology should be improved and correction factors estimated (Action 4.3.1) to improve the 158
accuracy and utility of population indices. This correction may require some banding at sites where there are currently no marked birds on which to base correction factors.

1.2 Develop and implement a program to monitor western snowy plover productivity and annual survival in each recovery unit. Development and implementation of a program to monitor western snowy plover productivity and survival, in addition to comprehensive population size and distribution monitoring, is necessary to measure progress toward achieving recovery criteria and to assess the effectiveness of management in removing threats that affect nesting success and survival. Results from this monitoring program also may be used to update the population viability analysis and assess progress toward recovery goals (Actions 4.11 and 6). Monitoring productivity and survival likely will be much more intensive than monitoring population sizes and distribution (Action 1.1), and cannot be implemented at all breeding sites because of insufficient color band combinations to monitor the entire Pacific coast population.

Plans for monitoring these demographic characteristics instead should utilize methods to sample demographic characteristics across the breeding range and in each recovery unit. Actions 4.3.2 and 4.3.3 recommend developing methodologies to estimate productivity and survival. The monitoring program should incorporate these methods and should specify the number of sites sampled in each recovery unit, how sites will be selected, and indicate control sites from intensively monitored breeding locations (i.e., the coast of Oregon, extreme northern California, and the shoreline of Monterey Bay).

1.3 Develop and implement a program to monitor at all breeding and wintering sites the habitat conditions, disturbances, predation, and other threats limiting abundance of breeding and wintering birds, clutch hatching success, chick fledging success, and survival.

Monitoring of threats to the western snowy plover is necessary to determine effectiveness of recovery actions in ameliorating or eliminating threats, assess progress toward recovery, and refine site-specific managements as necessary. A standardized threats monitoring program 159
should be developed and applied to all breeding and wintering sites in conjunction with monitoring developed and implemented under actions

1.1 and 1.2. At a minimum, monitoring should include determining substrate characteristics and vegetation composition (level of nonnative species), frequency and levels of disturbance (e.g., recreational activities, pets, vehicles, horses), and presence and abundance of predators.

Appendix J (Monitoring Guidelines) provides general guidance on monitoring but may require revision as research actions under action 4 are completed. Opportunities to incorporate monitoring into Federal activities subject to section 7 of the Endangered Species Act, such as dredging and discharges regulated by the U.S. Army Corps of Engineers, should be utilized when possible.

1.4 Develop and implement training and certification programs for western snowy plover survey coordinators and observers, consistent with recommendations in Appendix J (Monitoring Guidelines).

Classroom and field training are required for observers who survey for western snowy plovers, and before we can issue a section 10(a)(1)(A) permit. Instruction programs and materials should be developed for comparable training to occur throughout the western snowy plover range to improve consistency of data collection. Classroom topics should include, but not be limited to: (1) biology, ecology, and behavior of breeding western snowy plovers; (2) identification of adult plovers, their young, and their eggs; (3) threats to plovers and their habitats; (4) survey objectives, protocols, and techniques; (5) regulations governing the salvage of carcasses or eggs; (6) special conditions of existing recovery permits; (7) field identification of potential western snowy plover predators; (8) biology and behavior of predator and scavenger species; and (9) other activities (e.g., banding). Field training should include, as appropriate: (1) locating, identifying, and monitoring nests; (2) handling eggs and capturing and handling adults or chicks; (3) specifics on the target activity for which a recovery permit is to be issued, or under which an observer will work; (4) practical field exercises; and (5) field review of appropriate classroom topics.
160

1.5 Develop a submittal system for monitoring data to ensure consistent reporting among recovery units and sites, and annually review and revise the system as necessary. Initially, range-wide survey data will be limited to results from 2 annual window surveys. As population and demographic monitoring methods are developed and implemented (Actions 1.1, 1.2, 4.3.1, 4.3.2, and 4.3.3), a more sophisticated reporting and compiling system will be necessary. Our lead office should coordinate with researchers involved with monitoring to ensure that data collection, submittal, and entry systems remain current, include correction factors that account for lack of detections during surveys, and are consistent among recovery units and sites. An annual range-wide report should be developed and distributed to all interested parties. Additionally, consistent reporting of sightings of banded western snowy plovers is needed. Sightings of banded birds provide information on the wintering sites of breeding birds, use of multiple sites by breeding and wintering plovers, and survival and dispersal of adults and juveniles. In accordance with procedures of the U.S. Geological Survey, Bird Banding Laboratory, the Point Reyes Bird Observatory should continue to act as the color band coordinator for the Pacific coast population to avoid use of duplicate color banding schemes among researchers.

1.6 Assess and evaluate new breeding, wintering, and migration areas as they are discovered to determine threats and management needs and update lists of areas identified in Appendices B and C as data become available. As new western snowy plover breeding and wintering areas are discovered, data should be collected to assess site boundaries, habitat characteristics, population levels, and any significant threats. The current list of important breeding and wintering locations (Appendix B) should be expanded or refined as appropriate, and any new areas incorporated into management and monitoring plans. Areas determined to be important for migration through action 4.4.4 also should be evaluated and added to the list of areas requiring protection, management, and monitoring.

Management goals and needed management to ameliorate or eliminate threats should be developed for all new breeding, wintering, and migration 161
areas and should be included in periodic revisions of Appendices B and C of this recovery plan.

1.7 Annually coordinate monitoring of western snowy plovers and California least terns to minimize effects of disturbance to both species. Coordination with least tern monitors and managers is needed in all areas where western snowy plovers share breeding sites with California least terns. Coordination should take place at biannual pre-and post- season California least tern monitoring meetings. Protocols for monitoring California least terns should be revised as necessary so that western snowy plovers are not detrimentally affected. Human activities within some least tern colonies in southern California include monitoring by one to four people several days per week; maintenance of tern fences; predator management; site preparation; and banding/observation efforts.

Human activities associated with tern monitoring must be recognized as additional disturbance to western snowy plovers. Section 10(a)(1)(A) permits, issued under the authority of the Endangered Species Act for western snowy plovers and least terns, should include both species where applicable. Monitoring efforts for both species should be kept separate because of differences in monitoring techniques and species’ behaviors.

Monitors of least terns and western snowy plovers should be aware of species’ differences in nest spacing, brood-rearing, foraging behavior, time of breeding, vulnerability to disturbance, and monitoring and banding techniques.

Western snowy plovers generally begin nesting at least 1 month before the arrival of breeding least terns; thus, tern management often begins well after western snowy plovers have initiated nests. Site preparation (vegetation removal and fence construction) should be coordinated to minimize disturbance to nesting western snowy plovers, and if possible to enhance breeding success for both species (as well as considering other sensitive species, including plants, that may be present). Predator management also should be coordinated to benefit both species. 162

1.8 Develop post-delisting monitoring plan. Prior to delisting a five-year monitoring plan should be developed. Methodology and scope of post- delisting monitoring should be appropriately integrated with existing monitoring efforts for continuity and comparability. Monitoring and research results should be used to guide the long-term conservation of the species.
2 Manage breeding and wintering habitat of the Pacific coast population of the western snowy plover to ameliorate or eliminate threats and maximize survival and productivity. The Pacific coast population of the western snowy plover is sensitive to changes in productivity and in adult and juvenile survival rates (see Appendix D). Furthermore, recovery of this species is contingent on intensive management of breeding habitat and availability of wintering habitat for more than the current number of western snowy plovers (see recovery criteria). Appendix C provides a summary of site-specific management needs at 155 breeding and wintering locations (actions 2 and 3). Management efforts may be time-consuming, costly, and sometimes require intensive management.

Western snowy plover breeding habitat is extremely dynamic and factors affecting breeding success, such as types and numbers of predators, can change quickly; therefore, managers should be prepared to modify protection as needed.

Action 6 recommends annual review of progress toward recovery and revision of site-specific management actions based on monitoring and research results and site-specific experience. Management and protection of western snowy plovers on Federal and State lands are especially important. In addition, protection on Federal and State lands furnishes leadership by example to local land managers. Land managers should recognize that components of breeding habitat include: areas where plovers prospect for nesting sites, make scrapes, lay eggs, feed, rest, and rear broods. Breeding habitat also includes travel corridors between nesting, resting, brood-rearing, and foraging areas.

Wintering and migration habitats should also be monitored and managed to maximize survival and recruitment of western snowy plovers into the breeding population.
163

2.1 Maintain natural coastal processes that perpetuate high quality breeding and wintering habitat by incorporating the following recommendations into development of participation plans, management planning, and habitat protection (action 3) for the sites identified in Appendix C and any additional sites identified through surveys and monitoring. The dynamic nature of beach strand habitats as storm-maintained ecosystems should be recognized and allowed to function. Natural process that contribute to maintaining wide, flat, sparsely-vegetated beach strands preferred by western snowy plovers include: inlet formation, migration, and closure; erosion and deposition of sand dunes; and overwash and blowouts of beach and dune habitat.

Coastal development, beach stabilization, construction of rock jetties and seawalls, sand removal and dredging, water diversion and impoundment, and planting of nonnative vegetation interfere with these processes and result in loss and degradation of habitat.

Maintenance of natural coastal processes can be accomplished through establishment of management plans, conservation easements, fee title acquisition, zoning, and other means. Coastal development, beach stabilization, resource extraction, and water diversion and/or impoundment projects should be carefully assessed for impacts to wintering western snowy plovers. Recommendations from U.S. Fish and Wildlife Service offices (under the Endangered Species Act and Clean Water Act) and/or State agencies should focus on avoiding or minimizing adverse impacts to wintering habitat. Where adverse effects cannot be avoided, agencies should document impacts so that cumulative effects on this species' habitat can be assessed and compensated. When beach development cannot be avoided, the following protections should be implemented: (1) construction should take place outside the nesting season, (2) developers and others should be advised during planning stages that stabilization of shorelines will result in additional habitat degradation and that these impacts may affect evaluation and issuance of permits under the jurisdiction of the U.S. Army Corps of Engineers or State coastal management agencies, and of measures to minimize the impacts, (3) property owners (e.g., hotel or resort owners) should tailor 164
recreational activity on the beach and dunes to prevent disturbance or destruction of nesting western snowy plovers, their eggs, and chicks, (4) lights for parking areas and other facilities should not shine on western snowy plover habitat, (5) sources of noise that would disturb western snowy plovers should be avoided, and (6) the establishment of predator perches and nesting sites should be avoided when designing facilities.

Appendix C, Table C-1 identifies 86 locations which currently have development restrictions in place and 16 locations where development should be restricted or avoided to achieve management goals.

2.1.1 Develop a prioritized list of western snowy plover wintering and breeding sites where natural coastal processes need protection, or where impaired natural coastal processes should be enhanced or restored. Recovery Unit working groups should evaluate the sites within their recovery unit and determine where natural processes are likely to be disrupted or are in need of being enhanced or restored, or are of particular importance to maintaining high quality western snowy plover habitat. Sites should be prioritized based on their importance to western snowy plover breeding and the degree of threat to the western snowy plover and its habitat should natural processes be disrupted.

2.1.2 Identify mechanisms necessary to protect, enhance, or restore natural coastal processes for the sites identified in action 2.1.1 and implement through incorporating into actions 3.1 -3.10.

Mechanisms to protect, enhance, or restore natural processes may include development of management plans that prohibit or restrict activities that disrupt natural process (i.e. dredging or sand removal, recreational activities that contribute to excessive erosion or compaction), acquisition of habitat, landowner agreements, local land use protection measures, or enhancement activities.

Identification of these sites and mechanisms should be used to guide implementation of long-term management and protection under action 3.
165

2.2 Create and enhance existing and potential breeding and wintering habitat. Past and ongoing impacts to western snowy plover breeding habitat from development, artificial beach stabilization, and other projects have resulted in loss and degradation of western snowy plover habitat.

Habitat enhancement and creation are needed at multiple sites to offset these losses. Where impacts cannot be avoided, projects should remediate and compensate habitat loss and degradation by maintaining natural long- shore sand budgets and minimizing interference with natural patterns of sand accretion and depletion. When these types of projects are planned, complex natural sand movement patterns should be taken into account.

Beach management policies should recognize that many current erosion and sedimentation problems are the result of past property and/or inlet "protection" efforts. Habitat restoration projects in historic or potential breeding sites, where feasible, is encouraged. Creation of habitat should be emphasized in areas not subject to recreational impacts.

2.2.1 Remove nonnative and other invasive vegetation from existing and potential habitat and replace with native dune vegetation.

Land managers should implement remedial efforts to remove or reduce vegetation that is encroaching on western snowy plover breeding habitat or obstructing movement of chicks from nesting to feeding areas. Particular attention should be given to the eradication of introduced beachgrass (Ammophila spp.) within coastal dunes.

2.2.1.1 Develop and implement prioritized removal and
control strategies for introduced beachgrass and other
nonnative vegetation for each recovery unit. These
strategies should include early intervention to prevent expansion into breeding areas where introduced
beachgrass and other nonnative vegetation have not yet
spread or are in early stages of spreading. Attention also should be given to the removal of giant reed, Scotch
broom, gorse, iceplant, and shore pine. Remove/manage
vegetation on salt ponds, including levees.
166
Schedule/coordinate removal efforts to avoid disturbing nesting western snowy plovers. Appendix C, Table C-1
identifies 86 locations where removal of nonnative and
other vegetation is either currently occurring or needs to be initiated to achieve management goals.

2.2.1.2 Replace exotic dune plants with native dune
vegetation where it is likely to improve habitat for
western snowy plovers. Land managers should make
special efforts to reestablish native dune plants in western snowy plover nesting habitat, while concentrating on
removal of nonnative vegetation. Native dune vegetation includes American dunegrass (Leymus mollis), beach
morning glory (Calystegia soldanella), pink sand-verbena (Abronia umbellata), yellow sand verbena (Abronia
latifolia), beach bursage (Ambrosia chamissonis), grey
beach pea (Lathyrus littoralis), whiteleaf saltbush
(Atriplex leucophylla), and California saltbush (Atriplex californica). These efforts should be targeted for coastal dune sites that currently support nonnative vegetation
species such as introduced beachgrass (Ammophila spp),
and should be combined with removal of this invasive
plant. Seeds of local native dune plants collected within approximately 32 kilometers (20 miles) of the site to be planted should be used as replacement plant stock.

Revegetation efforts should be monitored to ensure that the amount of vegetative cover is compatible with
suitable breeding habitat for plovers.

2.2.2 Deposit dredged material to enhance or create nesting habitat.

Near-shore (littoral drift) and on-shore disposal of dredged material seems to be beneficial for perpetuating high quality western snowy plover nesting habitat in some instances and should be encouraged where appropriate. However, monitoring of habitat characteristics before, during, and after projects is needed, 167
particularly in cases of large operations occurring on sites where western snowy plovers nest or are deemed likely to nest following the disposal operation. On-shore disposal of dredged material should be scheduled outside the nesting season and, where possible, during seasons when birds are not present. In addition, dredged material must be clean sand or gravel of appropriate grain size and must be graded to a natural slope.

2.2.2.1 Evaluate western snowy plover breeding and
wintering sites listed in Appendix C and potential
breeding sites to determine whether dredged
materials may be used to enhance or create nesting
habitat. Recovery Unit working groups should identify
sites where dredged material may be used to enhance or
create nesting habitat. Evaluation of sites should include impacts (short- and long-term) to existing western snowy plover habitat, likelihood of use by western snowy
plovers, whether appropriate sources of clean dredged
material exist, and opportunities to utilize material from dredging projects.

2.2.2.2 Develop and implement plans, including pre- and post-project monitoring, to use dredged material to
enhance or create nesting habitat at the sites
identified in action 2.2.2.1. Plans to implement use of dredged material to enhance or create nesting habitat
should be developed for sites identified in action 2.2.2.1.

Plans should include measures to minimize impacts to
western snowy plovers and existing habitat and should
include pre- and post-project monitoring to determine
effectiveness of the project in enhancing or creating
nesting habitat.
168

2.2.3. Implement beach nourishment activities if action 4.1.2 indicates beach nourishment activities are effective in enhancing western snowy plover habitat. Beach nourishment activities have the potential to enhance western snowy plover habitat, but should be carefully evaluated to weigh the probable adverse and beneficial effects on plovers and on other sensitive coastal dune species.

2.2.3.1 Evaluate and identify sites where beach nourishment activities may be effective in creating and enhancing
western snowy plover habitat. Potential sites include
those sites where natural coastal processes have been
disrupted (i.e. by coastal development, beach
stabilization, construction of rock jetties and seawalls, etc.). Evaluation of sites should consider potential for adverse effects to existing western snowy plover habitat, whether appropriate sand sources are available, and
whether long-term benefits are likely to occur.

2.2.3.2 Develop and implement beach nourishment plans, including pre- and post-project monitoring for the
sites identified in action 2.2.3.1. Plans to implement beach nourishment activities to enhance or create nesting habitat should be developed for sites identified in action

2.2.3.1. Plans should include measures to minimize
impacts to western snowy plovers and existing habitat
and should include pre- and post-project monitoring to
determine effectiveness of the project in enhancing or
creating nesting habitat.

2.2.4 Create, manage, and enhance coastal ponds and playas for breeding habitat. Coastal ponds and playas, including salt ponds, should be enhanced and created to improve breeding habitat.

Significant opportunities for management of nesting plovers currently exist within San Francisco Bay salt ponds, Moss Landing 169
Wildlife Area, Bolsa Chica wetlands, and south San Diego Bay salt ponds. However, salt ponds should only be created or enhanced at existing salt pond habitat; they should not be used for mitigation or compensation of coastal beach-dune or other western snowy plover habitats. Creation of habitat should be emphasized in areas that would preclude or reduce recreational impacts.

Appendix C, Table C-1 identifies 15 locations where habitat enhancement is either currently in place or needs to be initiated to achieve management goals. Additional sites also may provide opportunities to enhance western snowy plover breeding habitat.

2.3 Prevent disturbance of breeding and wintering western snowy plovers by people and domestic animals. Disturbance by humans and domestic animals causes significant adverse impacts to breeding and wintering western snowy plovers. Because human disturbance is a primary factor affecting western snowy plover reproductive success, land managers should give the highest priority to implementation of management techniques to prevent disturbance of breeding birds. Western snowy plover breeding and wintering sites are highly variable in their amount of recreational activity. Land managers should conduct site-specific evaluations to determine whether recreational activities, domestic animals, and off-road vehicles pose a threat to plovers and implement appropriate measures. As information is gathered, it should be incorporated into conservation efforts. Management plans (Actions 3.3.1, 3.3.2, and 3.4) should include appropriate human/domestic animal access restrictions to prevent disturbance of western snowy plovers. Management techniques described below can reduce impacts of beach recreation on western snowy plovers, but they must be implemented annually as long as the demand for beach recreation continues.

2.3.1 Prevent pedestrian disturbance. Management measures to protect western snowy plovers should be determined on a site-by- site basis; factors to consider include the configuration of habitat as well as types and amounts of on-going pedestrian activity. On national wildlife refuges and State natural preserves within the 170
California State Parks system, where protection of wildlife is the paramount purpose of Federal and State ownership, western snowy plover habitat should be closed during the breeding season. Other areas also should be closed when necessary to adequately protect breeding western snowy plovers.

2.3.1.1 Restrict access to areas used by breeding western snowy plovers, as appropriate. Unless a beach is
closed to public entry, or use is minimal, posting and/or fencing of nesting areas is recommended to discourage
pedestrian use of the area and allow for plover courtship and prenest site selection, to prevent obliteration of
scrapes, crushing of eggs or chicks, and repeated flushing of incubating adults. Any access restrictions should be accompanied by outreach programs to inform the public
of any restrictions and provide educational material on the western snowy plover (see action 5).

2.3.1.1.1 Seasonally close areas used by breeding
western snowy plovers. Dates of seasonal
closures/restrictions should be based on the
best data available, and be coordinated by
geographic region for consistency in
communicating with the public. Closures may
be determined on a year-to-year basis and
other options such as fencing may be
considered first. To provide broods with
access to foraging areas, closures should cover
the area down to and including the water line,
where practical. Areas where territorial
plovers are observed also should be closed to
prevent disruption of territorial displays and
courtship. Because nests can be difficult to
locate, especially during egg-laying, closure
of these areas will also prevent accidental
171
crushing of undetected nests. Appendix C,
Table C-1 identifies 81 locations where public
access is either currently restricted or it is
recommended it be restricted to achieve
management goals.

2.3.1.1.2 Fence areas used by breeding western
snowy plovers. Fencing to keep people and
beach activities out of nesting/brood rearing
areas should not hinder chick movements,
unless fencing is specifically meant to keep
chicks from being harmed. Areas with a
pattern of nesting activity in previous year(s)
or where territorial plovers are observed
should be fenced before plovers begin nest-
site selection. Because nests can be difficult
to locate, especially during egg-laying, closure
of these areas will also prevent accidental
crushing of undetected nests. Symbolic
fences (one or two strands of 1/4 inch plastic-
coated steel cable strung between posts) with
signs identifying restricted areas substantially
improve compliance of beach-goers and
decrease people's confusion about where entry
is prohibited. On portions of beaches that
receive heavy human use during the breeding
season, fencing of prime brood-rearing areas
to exclude or reduce numbers of pedestrians
also should be implemented to contribute to
the survival and well-being of unfledged
chicks. Appendix C, Table C-1 identifies 64
locations where nesting areas are fenced or
where fencing is recommended to achieve
management goals.
172

2.3.1.1.3 Post signs in areas used by breeding
western snowy plovers. Areas with a pattern
of nesting activity in previous year(s) should
be posted before plovers begin nest-site
selection. On portions of beaches that receive
heavy human use during the breeding season,
posting of prime brood-rearing areas to
exclude or reduce numbers of pedestrians also
should be implemented to contribute to the
survival and well-being of unfledged chicks.

Appendix C, Table C-1 identifies 65 locations
where exclusionary signs are in place or
recommended to achieve management goals.

2.3.1.2 Locate new access points and trails well away from western snowy plover nesting and wintering habitat,
and modify existing access and trials as necessary.

Recreational users such as campers, clammers, anglers,
equestrians, collectors, etc., should be encouraged to
consistently use designated access points and avoid
restricted areas. Roads, trails, designated routes, and facilities should be located as far away from western
snowy plover habitat as possible. Recreationists using boats should be restricted or prohibited from areas being used by the western snowy plover. Appendix C, Table C- 1 identifies 67 locations where boat use is currently
and/or is recommended to be prohibited or restricted, and 81 locations where access is currently and/or is
recommended to be prohibited or restricted to achieve
management goals.
173

2.3.1.2.1 Evaluate existing and planned access at all
breeding and wintering locations and
determine whether access may adversely
affect western snowy plovers and their
habitat. Review of access points should
include evaluating level of and timing of use
by recreational users and level of effects on
the western snowy plover.

2.3.1.2.2 For sites where access is determined in
action 2.3.1.2.1 to adversely affect western
snowy plovers, develop and implement
plans to minimize effects. Actions that
could minimize effects of access include
seasonal restrictions, signs, fencing, or
relocation or modification of access points or
trails.

2.3.2 Implement and enforce pet restrictions. It is preferable that land managers prohibit pets on beaches and other habitats where western snowy plovers are present or traditionally nest or winter because any noncompliance with leash laws can cause serious adverse impacts to western snowy plovers. If pets are not prohibited, they should be leashed and under manual control of their owners at all times. Pets should be prohibited on beaches and other western snowy plover habitats if, based on observations and experience, pet owners fail to keep pets leashed and under full control.

Land managers should document the type and frequency of infractions of rules and regulations requiring pets on leash. This information, including the number of verbal warnings, written warnings, and notices to appear (citations), should be documented so that comparisons can be made between locations. This documentation could help ensure that adequate effort is being 174
made to enforce pet regulations. Appendix C, Table C-1 identifies 120 locations where pets are currently prohibited or restricted and where they are recommended to be prohibited or restricted to achieve management goals.

2.3.3 Annually review existing recreational activities at breeding and wintering sites listed in Appendix C and develop and
implement plans to prevent disturbance from disruptive
recreational activities where western snowy plovers are present. Some recreational activities may disrupt western snowy plover breeding and foraging, attract predators, destroy nests, or degrade habitat. Management of a variety of recreational activities is needed to minimize these effects. Special events, including sporting events, media events, fireworks displays, and beach clean- ups, attract large crowds and require special attention. Special events planned in western snowy plover nesting areas should not be held during the plover nesting season. Early planning and coordination with local resource agencies should be emphasized.

Fireworks should be prohibited on beaches where plovers nest.

When fireworks displays are situated to avoid disturbance to western snowy plovers, careful planning also should be conducted to assure that spectators will not walk through and throw objects into plover nesting and brood-rearing areas. Sufficient personnel also must be on-site during these events to enforce plover protection measures and prevent use of illegal fireworks in the vicinity of the birds.

Flying of kites and model airplanes should be managed to avoid adverse impacts in areas where nesting plovers are present. Sports such as ball- and frisbee-throwing should be managed within hitting and throwing distance of western snowy plover nesting areas because of tendencies for stray balls and frisbees to land in closed areas where they can smash nests and where efforts to remove them can disturb territorial or incubating birds. Camping and beach fires should be prohibited in western snowy plover 175
nesting areas during the nesting season. Appendix C, Table C-1 identifies 11 locations where kites are and/or should be prohibited and/or restricted to achieve management goals, but additional recreational activities also should be reviewed for potential adverse effects to western snowy plovers.

2.3.4 Inform beach users of restrictions on driftwood removal through posting of signs. Driftwood removal should not be allowed unless needed to create sufficient open habitat to induce nesting activities. In such cases, driftwood removal should occur outside of the breeding season. Appendix C, Table C-1 identifies 26 locations where driftwood collection restrictions currently occur and/or are recommended for restriction to achieve management goals. Driftwood removal should also be minimized through enforcement as identified in Action 2.3.8.

2.3.5 Prevent disturbance, mortality, and habitat degradation by prohibiting or restricting off-road vehicles, including beach- raking machines. Recreational off-road vehicles should be prohibited or restricted at western snowy plover breeding areas, as appropriate. Violations associated with unauthorized entry of recreational off-road vehicles into closed or fenced nesting areas should be strictly enforced. During the nonbreeding season, enforcement of violations regarding recreational off-road vehicle use should continue where western snowy plover use of beaches occurs year-round. Because of potential habitat degradation caused by mechanized beach cleaning, alternatives to this type of beach cleaning are recommended, including manual beach
cleaning by agency staff and volunteers knowledgeable about the need to maintain coastal dune habitat characteristics and to protect western snowy plovers. Appendix C, Table C-1 identifies 101 locations where off-highway vehicles are currently and/or recommended for prohibition or restriction to achieve management goals.
176
Essential vehicles within western snowy plover nesting areas should: (1) travel on sections of beaches where unfledged chicks are present only if absolutely necessary; (2) when possible, travel through chick habitats only during daylight hours; (3) travel at less than 8 kilometers (5 miles) per hour; (4) use a guide familiar with western snowy plovers; (5) use open four-wheel motorized off- highway vehicles or nonmotorized all-terrain bicycles to improve visibility; (6) avoid driving on the wrack (marine vegetation) line and during high-tide periods; (7) travel below the high tide mark and as close to the water line as is feasible and safe; and (8) avoid previous tracks on the return trip.

2.3.6 Implement restrictions on horseback riding in nesting areas through annual coordination with commercial and private equestrian operations and groups. Strategies to reduce adverse impacts to nests from commercial and private equestrian use of western snowy plover habitat should include: (1) use of designated trail systems or, when absent, use of the wet sand area in areas not closed to the water line; (2) advance coordination with local resource agencies regarding locations of nests and broods; (3) compliance with closed or restricted areas; and (4) informing riders of the need for restrictions to protect habitats used by western snowy plovers and other sensitive coastal dune species.

Avoid high-tide periods. Violations regarding unauthorized entry into closed or restricted breeding areas by equestrians should be strictly enforced. Appendix C, Table C-1 identifies 72 locations where restriction or prohibition of horses currently exists or is recommended to achieve management goals.

2.3.7 Implement and enforce restrictions on livestock in nesting areas through annual coordination with land managers,
landowners, and grazing lessees. Strategies to reduce adverse impacts to nests from livestock grazing in western snowy plover habitat should include: (1) advance coordination with local resource agencies regarding locations of nests and broods; (2) 177
compliance with closed or restricted areas; and (3) informing landowners of the need for restrictions to protect habitats used by western snowy plovers and other sensitive coastal dune species.

Violations regarding unauthorized entry into closed or restricted breeding areas by livestock should be strictly enforced. Appendix C, Table C-1 identifies 18 locations where restriction or prohibition of livestock currently exists or is recommended to achieve management goals.

2.3.8 Enforce regulations in areas used by breeding western snowy plovers. Land managers should monitor violations and enforce regulations within all closed and restricted areas, with particular attention to areas where nests or broods are present.

2.3.8.1 Determine enforcement needs for western snowy
plover breeding and wintering sites and provide
sufficient wardens, agents, or officers to enforce
protective measures in breeding and wintering
habitat. Wardens are especially needed on heavily-used beaches during the peak recreational season, which
coincides with the western snowy plover breeding season in many locations. Federal, State, and local authorities should provide a coordinated law enforcement effort to
eliminate activities that may adversely impact western
snowy plovers, such as illegally-parked vehicles,
trespassing off-road vehicles, pedestrians, pets in
restricted areas, illegal or unauthorized activities (e.g., fireworks, beach fires, driftwood removal), pets off leash, and littering. Patrols and enforcement are needed to
ensure compliance and to make sure restrictive measures are successful. Specific actions to be implemented
include patrols in protected areas (see action 2.3.8.2) and car patrols to prevent illegal driving and parking.

Appendix C, Table C-1 identifies 105 locations where
178
enforcement of regulations currently occurs or is
recommended to occur to achieve management goals.

2.3.8.2 Develop and implement annual training programs for enforcement personnel and others who work in
western snowy plover breeding habitat to improve
enforcement of regulations and minimize effects of
enforcement actions on western snowy plovers and
their habitat. Federal, State, and local enforcement
personnel and others who work in western snowy plover
habitat should be trained to be familiar with the
Endangered Species Act and other wildlife conservation
statutes, and with the measures recommended in this
recovery plan. Training, especially specific training for professional law enforcement agents regarding
investigation of potential wildlife and Endangered
Species Act violations, should be coordinated with local U.S. Fish and Wildlife Service Law Enforcement offices.

It is essential that wardens, whether professional or
volunteers, (1) be thoroughly trained in procedures for conducting patrols in a manner that minimizes risk to
plovers; (2) have at least basic knowledge of western
snowy plovers for public education purposes; and (3) be trained to handle potentially confrontational situations.

In cases involving take of listed species, it is essential that investigations be conducted only by trained,
certified, and professional law enforcement agents. Our local Law Enforcement office should be informed
immediately whenever evidence of suspected take of
western snowy plovers is encountered.

Enforcement personnel should be instructed in measures
that can minimize effects of enforcement actions on
western snowy plovers. Where the extent of habitat to be protected is large, making foot patrols infeasible, horses, 179
four-wheel all-terrain vehicles/off-road vehicles, or
nonmotorized all-terrain bicycles, are preferred over
trucks, automobiles, etc., because they afford improved visibility for operators. Except during emergencies,
vehicle speed should not exceed 8 kilometers (5 miles)
per hour and horses should be ridden at a walk only. In addition to providing maximum visibility for operators, horse and foot patrols by uniformed personnel have the
added advantage of providing informational/educational
interactions with beach visitors to promote compliance
with plover protection measures.

Enforcement and emergency response personnel (such as
search and rescue, and fire) should be well aware of
potential western snowy plover locations. These
locations should be named as avoidance areas as a part of their plans and training exercises. Enforcement patrols should use the same access trails as beach visitors; if additional access points are needed, they should be the minimum necessary and as far away from nesting plovers
as possible.

2.3.9 Develop and implement a program to annually coordinate with local airports, aircraft operations, and agency aircraft facilities to facilitate compliance with aviation regulations regarding minimum altitude requirements. Each recovery unit working group should develop a list of local airports, aircraft operations, and agency aircraft facilities within each recovery unit. Working groups, land managers, and the U.S. Fish and Wildlife Service should annually inform them of western snowy plover breeding areas that should be avoided by aircraft operations or where minimum altitude requirements should be enforced to minimize disturbance of western snowy plovers. Aircraft operations within western snowy plover habitat should require a minimum altitude of 152 meters (500 feet) for aircraft and a possibly higher altitude for 180
helicopters. Aircraft operations that have already established guidelines allowing aircraft to fly under the 152-meter (500-foot) threshold should raise the limits to this minimum threshold or higher as needed. Exceptions such as use for low-altitude military training should be addressed in coordination with the appropriate Fish and Wildlife Office through section 7 consultation.

Ultralight aircraft are a new potential source for negative effects to the snowy plover. Ultralight aircraft landed on nesting plover beaches at Point Reyes National Seashore in 2003. These aircraft are sometimes associated with an airport but often are kept on ranches or other private lands (S. Allen in litt. 2004).

In addition, land managers should report suspected violations of aviation regulations in western snowy plover nesting areas during the breeding season. Suspected violations and the aircraft’s registration number should be reported to law enforcement officers and, if appropriate, the Federal Aviation Administration. If not in violation of aviation regulations (e.g., helicopters), a description of the helicopter should be reported to law enforcement officers so they can notify the operator of the presence of, and potential for take of, western snowy plovers in nesting areas.

2.4 Prevent excessive predation for western snowy plovers. Land managers should employ an integrated approach to predator management that considers a full range of management techniques. Managers may need to reevaluate and clarify their policies on the management of predator populations and/or habitat where predation might be limiting local western snowy plover populations. In particular, policies that prohibit management of native predator populations, even when human- abetted factors have caused substantial increases in their abundance, may be counter-productive to the overall goal of protecting "natural" ecosystems.
181
In addition to predator management activities by on-site biologists, assistance from the U.S. Department of Agriculture (Wildlife Services Branch) biologists, State wildlife agency furbearer biologists, biologists specializing in avian predators, and professional trappers should be sought and used as needed and appropriate. Federal, State, and local agencies and the general public should be aware of the adverse consequences to listed species if needed predator control measures are prohibited or restricted. Appendix C, Table C-1 identifies 61 locations where predator control currently occurs or is recommended to achieve management goals.

Below are specific means of predator control.

2.4.1 Manage litter and garbage and its removal to minimize attracting predators on western snowy plover habitat. Litter and garbage in western snowy plover habitat may increase predation of western snowy plovers by providing food that attracts predators and encourages increased predator populations.

Appropriate management of litter and garbage, particularly in areas that receive heavy recreational use, is needed to prevent or minimize excessive predation.

2.4.1.1 Implement and enforce anti-littering regulations.

Litter should not be allowed in western snowy plover
breeding areas to avoid attracting predators. Littering ordinances should be enforced year-round.

2.4.1.2 Evaluate the effects of current litter and garbage management on predation of western snowy plover at
breeding and wintering sites. All sites in Appendix C
should be evaluated to determine whether garbage and
litter affect predation on western snowy plovers by
attracting predators.

2.4.1.3 Develop and implement garbage and litter
management plans for all sites identified in action

2.4.1.2 where litter and garbage contribute to
182
predation on western snowy plovers. Plans for
managing litter and garbage should be incorporated into long-term protection and management efforts developed
and implemented under action 3. Beachgoers should be
discouraged from leaving or burying trash or food scraps on the beach. Trash cans should not be located on the
beach unless there is no other recourse to prevent
littering. Emptying cans in the evening instead of leaving them overnight is preferable. Fish-cleaning stations
should be located well away from plover breeding areas.

Land managers should supply covered or scavenger-proof
trash receptacles at access points and away from western snowy plover habitat, and receptacles should be routinely emptied. Until predator-proof trash containers can be
installed, existing trash cans should be emptied
frequently to reduce attractiveness and availability of their contents to scavenging predators. Land managers
should also provide toilets at access points and away
from western snowy plover habitat to discourage people
from using the dunes.

Although removal of trash from the beach reduces
predation threats, beach-raking should be avoided year- round to protect breeding and wintering western snowy
plovers (see action 2.3.5). Beach-raking of western
snowy plover habitat also should be avoided because it
removes plover food sources. Trash should be selectively removed from the beach manually, but natural materials, including shells, kelp, and driftwood, should be left intact (see action 2.3.4).

2.4.2 Annually identify predator perches and unnatural habitats attractive to predators and remove where feasible. Planners should not allow unnatural habitats or other predator attractants to be placed near western snowy plover nesting locations. Where 183
feasible, land managers should remove from western snowy plover breeding locations any exotic vegetation, perches, and other features that attract avian and mammalian predators. Where signs and fences are necessary as part of management to protect plover breeding areas, attempts should be made to design them in a way that will deter their use by predators (e.g., install spikes on fence posts).

2.4.3 Erect predator exclosures to reduce western snowy plover egg predation and improve productivity (number of fledglings per male) where appropriate. Guidelines for the use of predator exclosures to protect nesting western snowy plovers are contained in Appendix F. Exclosures are a valuable tool for countering human-abetted predation threats to western snowy plover eggs, but they are not appropriate for use in all situations, nor do they provide any protection for mobile plover chicks, which generally leave the exclosure within one day of hatching and move extensively along the beach to feed. Exclosures should be used in conjunction with an integrated predator management program.

Also, exclosures must be carefully constructed, monitored, and evaluated by qualified persons. In some areas, avian predators have learned over time to associate exclosures with a source of prey (J. Buffa in litt. 2004). String (twine) or a more substantial plastic stealth material may be needed on top of exclosures to deter avian predators. Appendix C, Table C-1 identifies 53 locations where exclosures are currently used or recommended for use to achieve management goals.

The use of exclosures (small circular, square, or triangular metal fences that can be quickly assembled) to deter predator and human intrusion is recommended as one of the most effective
management tools to protect nests (see Appendix F for exclosure protocols). However, it should be recognized that while exclosures provide nest protection, they do not ensure survival of chicks to fledging age and may contribute to predation on adults, 184
so their use should be evaluated carefully and may not substitute for other measures that reduce human disturbance (2.3) or control predation (2.4.1, 2.4.2, 2.4.3, 2.4.5).

2.4.4 Evaluate the need for and feasibility of predator removal and implement removal where warranted. Where predators have been identified through monitoring to adversely affect western snowy plover breeding success and/or survival and cannot be adequately controlled through use of exclosures, land managers should evaluate the need for and feasibility of predator removal.

Removal of predators should be pursued where it is feasible, warranted, humanely conducted, and useful. Situations that may especially warrant predator removal include those where nonnative predators such as red fox (Vulpes vulpes regalis), feral cats, and Norway rats (Rattus norvegicus) are present, where predators have been introduced to islands, where predator range extensions have been human-abetted, or where high rates of western snowy plover adult, chick, or egg predation (which cannot be countered with predator exclosures or other aversion methods) are occurring.

Nonnative predators should be lethally controlled in plover nesting habitat. Native predators should be removed or controlled by nonlethal means whenever possible. Gulls also should be discouraged from establishing and expanding nesting colonies at western snowy plover nesting areas, and land managers should determine whether existing gull colonies warrant removal. If removal is not warranted, exclosures around plover nests should be used to prevent large flocks of roosting gulls from trampling plover nests.

Federal and State permits must be obtained to legally capture, kill, or hold and release birds protected under the Migratory Bird Treaty Act and State laws. Also, individuals responsible for capturing such birds and the holding facility must have the proper Federal and State permits, and Federal land managers must document that such activities are in compliance with the National 185
Environmental Policy Act. Biological considerations for determining whether removal of avian predators is appropriate include the time of year (to assess whether the predator is caring for young or is a fledgling itself), whether the predatory bird is a resident or migrating through western snowy plover nesting habitat, and whether the predatory bird is a sensitive species or listed under the Endangered Species Act. Because of the potential for swift and significant losses of plovers by avian predators, land managers should plan in advance to complete the necessary procedures and secure needed permits to effectively deal with cases of high negative impact on western snowy plovers. If feasible, removal of native predators should focus on problem individuals rather than populations. Possible control methods include egg addling, nest removal, translocation of problem individuals, and holding in captivity with later release after plover breeding season. State permits must also be obtained as appropriate for the capture and removal of problem mammals (e.g., raccoons, skunks, and opossums). In 2001, the California Coastal Commission determined that predator management in western snowy plover habitat on Vandenberg Air Force Base was also subject to Coastal Consistency review under the Coastal Zone Management Act.

2.4.5 Remove bird and mammal carcasses in western snowy plover nesting areas. Where practical and not disturbing to western snowy plovers, dead birds and mammals that wash up on the beach in close proximity to plover nests should be removed to reduce the attraction of predators to plover nests. Removal of carcasses of marine mammals and species listed under the Endangered Species Act should be coordinated with the National Marine Fisheries Service and the U.S. Fish and Wildlife Service.

2.5 Protect western snowy plovers and their breeding and wintering habitat from oil or chemical spills. Land managers should develop oil/chemical spill emergency response plans that provide for protection of 186
known western snowy plover breeding areas. The U.S. Coast Guard should update their emergency response measures to include protective measures for the western snowy plover. In the event of a spill in the vicinity of a western snowy plover nesting or feeding area, efforts should be made to prevent oil/chemicals from reaching these beaches. Clean-up operations should be prompt, but agencies should exercise special care during remediation efforts and coordinate closely with us to prevent accidental destruction of nests and/or excessive disturbance of breeding adults, nests, or chicks. Response plans should include applicable recommendations contained in this recovery plan (e.g., Action 2.3.5 regarding essential vehicles).

Efforts must be made to minimize the likelihood of oil or chemical spills in plover wintering areas. Land managers should develop oil/chemical spill emergency response plans that provide for protection of known plover wintering areas. The U.S. Coast Guard should update their emergency response measures to include protective measures for the western snowy plover. Shorebird or coastal ecosystem protection plans developed by State or local agencies to address oil/chemical spills should also include protection measures for western snowy plovers. In the event of a spill in a known western snowy plover wintering area, efforts should be made to prevent oil/chemicals from impacting plovers and unavoidable impacts should be documented. Restoration efforts should begin expeditiously, but agencies should exercise special care and coordinate closely with us to prevent excessive disturbance to wintering western snowy plovers. Further, habitat restoration efforts must be conducted in compliance with the National Environmental Policy Act and the Coastal Zone Management Act.

If western snowy plovers or their habitat sustain injury due to oil/chemical spills, the responsible parties should restore the areas to their original condition or the Federal Government (U.S. Coast Guard) should lead the clean-up effort; appropriate claims should also be filed under the Natural Resource Damage Assessment regulations to recover damages and undertake relevant restoration work. Assessment of natural resource 187
damages is facilitated by availability of baseline data on pre-spill conditions. Therefore, whenever possible, agencies that own or manage western snowy plover habitat should collect baseline data on behavior, reproduction, distribution, abundance, and habitat use. The baseline information on plover distribution and habitat use should also be supplied to the Area Committees that develop and update regional spill contingency plans so that this information can be incorporated into pre-spill planning efforts for protection of sensitive environments and species. Oil spill emergency response personnel should be well aware of potential plover locations. These locations should be named as avoidance areas as a part of their training exercises. Appendix C, Table C-1 identifies 4 locations where contaminant removal is occurring or is recommended to achieve management goals.

2.5.1 U.S. Fish and Wildlife Service biologists should participate in Area Committees responsible for maintaining the Area Contingency Plans for the Pacific Coast to facilitate the updating of spill response plans to include protection of western snowy plovers. Active participation in the Area Committees would require funding for staff participation from the six U.S. Fish and Wildlife Service offices responsible for the coastlines of California, Oregon and Washington.

2.5.2 Assign monitors to beaches that are inhabited by western snowy plovers to protect western snowy plovers from injury during spill responses. Monitors would be responsible for identifying areas of beach that are in use by plovers and directing response personnel and vehicles around these sensitive areas.

Potential monitors should be identified in advance, and, where necessary, retained under contract so they can begin work immediately in the event of a spill. Spill response may require approximately two weeks of cleanup work that should be
monitored, with potentially five incidents of this magnitude per year.
188

2.6 Reduce adverse impacts of recovery efforts for other sensitive species, including those within the San Francisco Bay Recovery Unit, by compensating for the loss of western snowy plover breeding and wintering habitat. Management and recovery actions for other sensitive species carried out in western snowy plover habitat should be evaluated for adverse effects to western snowy plover habitat. All efforts should be made to conserve western snowy plover habitat and minimize adverse effects. Where this is not possible, any loss of western snowy plover habitat values should be compensated. Within coastal beach-dune habitats in Washington, Oregon, and California, compensation efforts should emphasize the removal of beachgrass (Ammophila spp.) for lost western snowy plover breeding habitat resulting from management for other sensitive species.

To compensate for the loss of existing western snowy plover breeding habitat values in San Francisco Bay from planned conversion to tidal marsh, appropriate salt ponds should be designated for protection and enhancement as western snowy plover breeding habitat. Currently, most western snowy plover breeding habitat occurs on levee roads, margins of active salt ponds, and pond bottoms of inactive salt ponds. Roads and levees provide lower quality habitat because of disturbance and ease of predator access. Any losses of western snowy plover breeding habitat should be replaced with habitat that provides similar or higher values (i.e., salt ponds or salt pans) in concert with recovery actions implemented from the Recovery Plan for Tidal Marsh Ecosystems of Northern and Central California (U.S. Fish and Wildlife Service in prep.). Habitat enhancement for western snowy plovers should be phased in with scheduled tidal marsh restoration for other listed species. During this interim period, land managers should make all efforts to achieve the recovery criteria of 500 breeding adults within the San Francisco Bay Recovery Unit by intensively managing existing western snowy plover breeding habitat.

Any replacement of western snowy plover breeding habitat in San Francisco Bay should concentrate on areas where the necessary 189
components of western snowy plover breeding habitat can be created.

These areas include locations where unvegetated salt pans, salt ponds, islets and levees, and tidal mudflats/sandflats can be created or enhanced.

Also, attempts should be made to avoid areas that are adjacent to landfills or other high concentrations of potential predators. Unless it is shown to be infeasible, creation and enhancement of western snowy plover breeding habitat should be emphasized in areas that currently support high numbers of breeding plovers and/or are not conducive to salt marsh restoration.

The area to be managed for western snowy plovers should be sufficient to support a population of 500 breeding birds, estimated at 809 hectares (2,000 acres) of managed salt ponds. Most of these managed salt ponds should be located in South San Francisco Bay, which supports most of the existing western snowy plover population; however, some should also be located in the North Bay. Created or enhanced salt ponds should be intensively managed, similar to the Moss Landing Wildlife Area salt ponds. Management measures practiced at these salt ponds include maintenance of water control structures to maintain desired water levels, removal of excessive vegetation, and predator control.

2.7 Discourage pinnipeds from usurping western snowy plover nesting areas. Land managers should monitor pinniped colonies adjacent to western snowy plover breeding habitat and seek to keep breeding pinnipeds from occupying western snowy plover nesting areas during the breeding season where possible. Where conflicts occur, breeding pinnipeds should be discouraged from hauling out at western snowy plover breeding areas or be relocated, if feasible. Implementation of this action should be coordinated with the National Marine Fisheries Service to ensure compliance with the Endangered Species Act of 1973 and the Marine Mammal Protection Act of 1972 (16 U.S.C. 1361 et seq.).

2.7.1 In coordination with National Marine Fisheries Service, investigate feasibility and methods for discouraging pinniped use of western snowy plover nesting areas. Marine mammal populations have increased in many western snowy plover nesting areas. However, methods, effectiveness, and impacts of 190
discouraging pinniped use of beaches are unknown and should be investigated. Methods considered should be evaluated for their effects on western snowy plovers and their habitat as well as effectiveness in discouraging pinniped use. Workshops, such as those conducted by NMFS, for developing methods to reduce conflicts between pinnipeds and other species and human users should be held.

2.7.2 Identify areas where pinniped use is negatively affecting western snowy plover nesting and implement any appropriate methods identified in action 2.7.1. If effective methods are determined through action 2.7.1, sites where pinniped use negatively affects western snowy plover nesting should be identified and methods to discourage pinniped use implemented.

Implementation of any methods to discourage pinniped use should be closely coordinated with the National Marine Fisheries Service to ensure compliance with the Endangered Species Act of 1973 and the Marine Mammal Protection Act of 1972 (16 U.S.C. 1361 et seq.).
3 Develop mechanisms for long-term management and protection of western snowy plovers and their breeding and wintering habitat. Long-term management and protection will be needed on Federal and non-Federal lands to meet recovery criteria for each recovery unit and to meet management goals for individual breeding and wintering locations. Development of long-term protection mechanisms should include opportunities for participation of various stakeholders in development of management options.

3.1 Establish and maintain western snowy plover working groups for each of the six recovery units to facilitate regional cooperative networks and programs. Development of regional cooperative networks and programs, coordinating local public and private land use planning with State and Federal land use planning, recovery planning, and biodiversity conservation is needed (Figure 12). To facilitate and develop regional cooperative programs, working groups have been established for each of 191
the six recovery units and should be maintained. U.S. Fish and Wildlife Service field offices should facilitate exchange of information among working groups. The working groups should be composed of representatives from the Federal, State, local, and private sectors; and meet regularly to assess western snowy plover population trends and coordinate plover recovery efforts. Each of the six working groups should use this recovery plan as a guide, but members will prioritize in cooperation with our Arcata Fish and Wildlife Office what management measures need to be implemented in their recovery unit because they have on-the-ground, day-to-day, experience about what is currently being done in these areas. Working groups should assist with updating information contained in Appendices B and C, tracking whether management goals are being met, and recommending changes in management goals and site- specific management actions, if necessary. Public outreach also should be a major focus of the working groups. An interchange of ideas between all six working groups should also occur on an on-going basis.

3.2 Develop and implement regional participation plans for each of the six recovery units that outline strategies to implement recovery actions.

The 1994 Interagency Cooperative Policy on Recovery Plan Participation and Implementation Under the Endangered Species Act (U.S. Fish and Wildlife Service and National Oceanic and Atmospheric Administration 1994) provides for a participation plan process, which involves all appropriate agencies and affected interests in a mutually-developed strategy to implement recovery actions. Participation plans for implementing recovery actions for the western snowy plover that include all partners should be developed by each of the six recovery unit working groups. In addition to outlining a strategy to implement recovery actions, the participation plan should include strategies for evaluation of progress and needs for plan revision. Participation plans may also achieve the policy’s goal of providing for timely recovery of species while minimizing social and economic impacts. Plans should identify and prioritize specific recovery activities for each location identified in Appendices B and C,while considering the needs of the entire Pacific coast population. They 192

Figure 12. Chart of recovery planning and implementation efforts.

Arcata Fish and Wildlife Office, U.S. Fish and Wildlife Service Implement Recovery
Coordinate and dist ribute monitor ing data and educati onal material s (Action 7) Compile and distri bute annual stat us updates (Action 7) Coordinate plover conservation act ions, consult ations, HCP’s and permi tting (Action 7)
Recovery Unit Working Groups (6)
Develop partici pation plans ( Action 3.1.2)
U.S. Fish and Wildlife Service
Facilitat e formation and maint enance of plover worki ng groups for each r ecovery unit (Act ion

3.1)
Assist State agencies, local governments, and pri vate landowners in deve loping management plans and Habitat Conservati on Plans (Action 3. 3, 3.4)
Private Landowners
Develop and implement management pl ans and Habitat Conservat ion Plans (Action 3. 4)
Federal Agencies
Develop and implement management pl ans for Federal lands (Action

3.3.1)
State Agencies
Develop and implement management pl ans and Habitat Conservat ion Plans (Action 3. 3.2)
Local Governments
Develop and implement management pl ans and Habitat Conservat ion Plans (Action 3. 4)
Develop and implement land- use protecti on measures (Action 3. 5) 193
should include, but not be limited to: (1) endorsements by responsible agencies of their intent to seek economic resources for ongoing recovery actions; (2) outreach efforts to enhance the public’s understanding of the western snowy plover’s habitat needs (including an information and education strategy specific to area demographics and recreational activities); (3) economic incentives for conservation of western snowy plovers on private lands; and (4) all actions necessary to maintain western snowy plover productivity after delisting. Participation plans may also identify ways in which recovery actions for western snowy plovers will be covered as part of coastal ecosystem plans or other conservation measures.

3.3 Develop and implement management plans for all Federal and State lands to provide intensive management and protection of western snowy plovers and their habitat. Federal and State land managers should develop and implement management plans for all breeding and wintering locations (listed in Appendix B) that occur on Federal or State lands. Intensive management programs for western snowy plovers at national wildlife refuges should be implemented and annually evaluated to ensure they provide sufficient plover protection. Intensive management programs also should be implemented and periodically evaluated on lands administered by the National Park Service, U.S. Forest Service, U.S.

Bureau of Land Management, U.S. Army Corps of Engineers, and Federal military bases, State wildlife areas, State ecological reserves, and State park lands (including State natural preserves and State seashores).

3.3.1 Develop and implement management plans for Federal lands.

Federal agencies should develop or update, as appropriate, site- specific management plans that address threats to western snowy plovers, and adopt management measures for habitat protection and enhancement on Federal lands. Management plans should be implemented on an ongoing basis. Federal agencies also should review their proposed actions under the requirements of sections 7 and 10 of the Endangered Species Act prior to implementing the management plans because they may require authorization under section 7(a)(2) or 10(a)(1)(A).
194

3.3.2 Develop and implement management plans and habitat conservation plans on State wildlife areas, State ecological reserves, and State beaches. State agencies that manage State beaches, wildlife areas, or ecological reserves should develop and implement site-specific management plans and habitat
conservation plans to minimize and mitigate impacts to western snowy plovers, and management measures for habitat protection and enhancement on State lands. State agencies should coordinate the development of habitat conservation plans with us and apply for section 10(a)(1)(B) permits under the Endangered Species Act if their management actions and allowed uses are resulting in incidental take of western snowy plovers.

3.4 Develop and implement habitat conservation plans or other management plans for western snowy plover breeding and wintering sites owned or managed by local governments and private landowners. We should provide assistance in the development of habitat conservation plans or other management plans to: (1) county and city governments that manage western snowy plover habitats; (2) private resource managers; and (3) owners of large amounts of private natural land. Habitat conservation plans are only required if an incidental take permit under section 10(a)(1)(B) of the Endangered Species Act is desired or required.

3.5 Provide technical assistance to local governments in developing and implementing local land use protection measures through periodic workshops. Federal and State agencies should assist local governments with jurisdiction over western snowy plover habitats in developing western snowy plover protection policies as part of new or revised local general plans, zoning policies, implementing measures, land use plans, comprehensive plans, and local coastal programs. For areas where beach closures are necessary, appropriate ordinances, administrative rules, and regulations should be developed by State and local governments to enable law enforcement officers to conduct necessary enforcement actions. 195
Technical assistance such as maps of western snowy plover habitats, identification of local threats, and recommended site-specific protective measures should be provided to coastal planners. At least two workshops within each recovery unit that provide local governments with basic information on the western snowy plover, its habitats, threats, and recommended protective measures should be conducted during the first 10 years of recovery plan implementation. Additional technical assistance likely will be required but should be provided on an as needed basis as new or revised general plans, policies, ordinances, and other land use protection measures are developed.

3.6 Develop and implement cooperative programs and partnerships with the California State Coastal Commission, the Oregon Department of Land Conservation and Development, the Washington State Parks and Recreation Commission, the Oregon Parks and Recreation Department, the California Department of Parks and Recreation, and the Oregon Department of Fish and Wildlife to ensure that they use their authorities to the fullest extent possible to promote the recovery of the western snowy plover. Federal and State agencies should assist the California State Coastal Commission, Oregon Department of Land Conservation and Development, Washington State Parks and Recreation Commission, Oregon Parks and Recreation Department, California Department of Parks and Recreation, and Oregon Department of Fish and Wildlife in reviewing, updating, and amending local coastal programs and policies for consistency with the western snowy plover recovery plan.

This review should include protection of western snowy plover habitats, cumulative impacts to western snowy plovers, and policies or restrictive measures recommended in this recovery plan.

3.7 Obtain long-term agreements with private landowners.

Agreements between Federal and State agencies and private landowners interested in western snowy plover conservation should be developed and implemented. Landowners should be informed of the significance of plover populations on their lands and be provided with information about available conservation mechanisms, such as agreements and incentive 196
programs. For private lands with potential occurrences of western snowy plovers, permission should be sought from landowners to conduct on-site surveys. If surveys identify plover populations, landowners should be informed of their significance and offered incentives to continue current land uses that support species habitat. Appendix C, Table C-1 identifies 69 locations where landowner cooperation/cooperative agreements are occurring or are recommended to achieve management goals.

3.8 Identify and protect western snowy plover habitat available for acquisition. Federal, State, and private conservation organizations should protect western snowy plover habitat as it becomes available, through fee title or conservation easement, etc. We and other organizations should identify sites that may become available for acquisition, and we should continue to evaluate excess Federal lands for western snowy plover habitat and apply to acquire them as they become available. Each recovery unit working group should develop a list of priority properties for acquisition, and Federal, State, and nongovernmental organizations should work with land conservancy groups to implement land trades and acquisitions.

Management plans for the western snowy plover should be developed during the land acquisition process.

3.9 Ensure that section 10(a)(1)(B) permits contribute to Pacific coast western snowy plover conservation. Recommendations contained in this recovery plan should guide the preparation of habitat conservation plans under section 10(a)(1)(B) of the Endangered Species Act for western snowy plovers on the Pacific coast by providing information to: (1) guide potential applicants in developing plans that minimize and mitigate the impacts of take and (2) assist us in evaluating the impacts of any proposed conservation plans on the recovery of the Pacific coast western snowy plover population. The section 10(a)(1)(B) permit process may be a valuable mechanism for developing the long-term protection agreements called for in Actions 3.3.2 and 3.4, especially where significant population growth has already occurred and productivity exceeds l.0 fledged chick per male.
197

3.10 Ensure that consultations conducted pursuant to section 7 of the Endangered Species Act contribute to Pacific coast western snowy plover conservation. The recovery plan should also guide the evaluation of impacts to western snowy plovers pursuant to section 7(a)(2) of the Endangered Species Act. In evaluating these impacts, we and other Federal agencies should consider each of the breeding and wintering locations listed in Appendix B as important for recovery, and should also refer to the management goal breeding numbers for applicable locations and determine how the proposed project will affect those goals.

Coordination with military bases which have western snowy plover populations is important to ensure that military activities do not affect the western snowy plovers or their habitat. Appendix C, Table C-1 identifies 54 locations where military uses are either restricted or recommended for restriction to achieve management goals.
4 Undertake scientific investigations that facilitate recovery efforts. Major gaps remain in our understanding of useful protection measures and conservation efforts for the western snowy plover. These include effective methods for habitat restoration, predator control, and monitoring population numbers and demographic characteristics.

4.1 Investigate effective methods for habitat restoration.

4.1.1 Evaluate the effectiveness of past and ongoing methods for habitat restoration by removal of introduced beachgrass and identify and carry out additional investigations necessary.

Land managers, in coordination with recovery unit working groups, should summarize methods used to date for removal of introduced beachgrass and review their effectiveness. They also should pursue any additional field studies necessary to determine the most effective and cost-efficient methods for habitat restoration through removal of introduced beachgrass. Controlled studies with improved monitoring would provide needed direction for
management decisions.
198

4.1.2 Evaluate the impacts and potential benefits of past and ongoing beach nourishment activities and identify and carry out any additional studies necessary to determine effects of beach nourishment activities on western snowy plover habitat.

Beach nourishment activities should be carefully evaluated to weigh the probable adverse and beneficial effects on plovers and on other sensitive coastal dune species. Pre- and post-deposition beach profiles and faunal studies (including invertebrates) should be conducted to determine effects on habitat suitability for western snowy plovers. Consideration should be given to whether the projected long-term benefits are likely to occur.

4.2 Develop and test new predator management techniques to protect western snowy plover nests and chicks. Because many of the techniques currently used to reduce predation have disadvantages or limitations in effectiveness, new predator management techniques should be investigated. Assistance from the U.S. Department of Agriculture, Wildlife Services Branch, from State wildlife agency furbearer biologists, and other predatory bird and mammal specialists should be sought on these matters.

4.2.1 Develop higher-efficiency nest exclosures. Because exclosures must be deployed quickly, and currently-designed exclosures are heavy and labor- and time-intensive to erect, new exclosure designs should be tested. Prototypes should include lightweight materials that are easier to transport and a design that is easy to assemble and install.

4.2.2 Develop California least tern exclosures that prevent harm to western snowy plovers. Resource managers should continue to investigate modified designs for California least tern enclosures to further minimize western snowy plover mortality.

4.2.3 Identify, prioritize, and carry out needed investigations on control of native and nonnative predators. Aspects of the 199
ecology of problematic avian predators (e.g., ravens and shrikes) and native mammals (e.g., coyotes and gray foxes) that could be used to gain an understanding of how to control their impact on western snowy plover nesting areas during the plover breeding season should be investigated. Information also is needed on the applicability and usefulness of other control methods, including aversive techniques for conditioning predators to avoid foraging in western snowy plover nesting areas or preying on western snowy plover eggs, chicks, or adults. Investigation is also needed to develop methods to discourage gull colonies. Aversive techniques may include taste aversions, displaying predator carcasses, or installing electric fences. Effective modifications of signs and fencing to prevent their use as predator perches also requires investigation. While in many cases there appear to be practical obstacles to development of effective aversion techniques that can be efficiently applied in the field, the goal of reducing predation with minimum disruption to native predator populations that are important to overall ecosystem balance is desirable and any methods that appear potentially practical and useful should be evaluated for success and cost-effectiveness. Initial study trials might be done at sites or seasons where western snowy plovers are not present in order to minimize unplanned adverse impacts.

Recovery unit working groups should identify and prioritize studies needed and inform us of their recommendations.

4.2.4 Identify, prioritize, and carry out needed investigations on predator management at the landscape level. Resource
managers should investigate landscape-level management of predators that inhabit western snowy plover nesting areas. This management could include removal of predator nest sites and other predator attractants or habitat on lands surrounding western snowy plover breeding areas. Recovery unit working groups should identify and prioritize studies needed and inform us of their recommendations.
200

4.2.5 Investigate techniques for identifying predators responsible for individual nest predation events. Techniques should be developed to identify predators responsible for nest predation events so that appropriate management measures can be applied.

Such techniques could include installation of a remote video camera to monitor western snowy plover nests and exclosures and identify problematical predators.

4.3 Improve methods of monitoring population size and reproductive success of western snowy plovers. Methods used to monitor western snowy plover populations have differed over time and from site to site.

To measure progress toward recovery reliably, standard monitoring guidelines have been developed (Appendix J). Logistical and financial constraints likely will preclude complete coverage of all areas, so sampling methods should be developed.

4.3.1 Improve methods of monitoring western snowy plover population size. Not all western snowy plovers at a given location are detected during a single survey, such as the annual breeding- season window survey. Consequently, correction factors are necessary to extrapolate population size from window surveys.

Correction factors are determined on a site-specific basis.

Intensive monitoring and/or color banding make it possible to know the number of western snowy plovers present at a site.

When a window survey is completed, the ratio of the total number of western snowy plovers to the number of western snowy plovers counted provides a correction factor that may be used for future window surveys of the site and for other sites with window surveys but without intensive monitoring. Site-specific correction factors should be obtained for all major nesting locations. When correction factors have been determined for many sites, patterns may emerge that allow correction factors to be applied more broadly.
201

Long Beach City CouncilMarch 21, 2023

Long Beach City Council
March 21, 2023