McMillan, Acquanette (Netta)
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Candy Rinard <
Monday, July 17, 2023 1:04 PM
PublicComment-AutoResponse
Killing of Coyotes
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Here we go again. Why do cities think that they can trap and kill their wildlife and that residents would be okay with that? You are causing the issue that you are trying to fix. Killing never works with coyotes. You just get bigger populations. I have been to your city council meetings and offered up a solution to your problem many times, but you never want to spend a dime to take care of this. You need an expert in wildlife behavior (and I am not speaking about animal control). When Arcadia tried this very thing they had been speaking with Littlebluesociety.org and had Mary Paglieri willing to come to their city and make a plan to coexist with the coyotes. After a resident sued them they dropped the trapping and killing, but then they also dropped Mary Paglieri. I guess being fined was too much for them and they didn't want to spend any extra to actually solve the issue. Please contact this woman. Stop killing our wildlife. It's shameful and makes your city look horrible.
Candy Rinard
About-_Little Blue Society
1 7/17/2023
Item 9
McMillan, Acquanette (Netta)
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Ed Simpson
Monday, July 17,2023 1:21 PM
PublicComment-AutoResponse
Coyotes in Pasadena
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Dear Mayor and City Council:
Thank you for your actions regarding coyote complaints. South Pasadena had similar complaints in 1982. A Coyote Committee of residents was created by the Council. I was appointed to that Committee. We met with experts on coyote behavior and others who helped the Committee understand the interaction of coyotes and humans.
The report by the Committee was well received by the City Council who created an Animal Commission. Through the years that Commission received some complaints about coyotes, and the Commission scheduled coyote community education presentations with Pasadena hlumane Society. That has worked for our City, and I believe it will work in Pasadena.
Education as to not leaving pet food outside, not feeding coyotes intentionally and making sure trash is not left available, all these and others as listed in your Option 3 are most important.
We strongly urge you adopt Option 3. "Direct staff to implement one or more of the five staff recommendations listed in the response to the Public Safety Committee." All five of those staff recommendations are excellent.
Thank you for giving the time and research before making your decision.
Sincerely,
Edward L. Simpson
1 7/17/2023
Item 9
McMillan, Acquanette (Netta)
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Ruta Soltanpour
Monday, July 17,2023 1:19 PM
PublicComment-AutoResponse
Please support Option 3
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Council members,
Please listen to the science and support the recommendations being made by staff (Option 3) to gain a better understanding of Pasadena's coyote population and how to best prevent conflicts between humans and coyotes, and not resort to trapping and killing.
Thank you,
Ruta Soltanpour
1 7/17/2023
Item 9
McMillan, Acquanette (Netta)
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Marina Drake
Monday, July 17, 2023 1:47 PM
PublicComment-AutoResponse
Coyote Management Plan
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To the Pasadena City Council members,
This evening, the Pasadena City Council will decide whether to change its coyote-management plan to include cruel, ineffective, and expensive lethal methods. I'm writing to urge the city to stick to humane, effective, nonlethal methods of coyote control.
A few people who own homes near the Arroyo have been complaining to their council member, Steve Madison, that they see an increase in coyotes and demanding that the city study Torrance's lethal approach to coyote management, which has involved snaring and gassing coyotes since 2019. Coyote sightings have risen sharply in Torrance despite an expanded trapping program that's costing taxpayers $80,000 annually, and there are no fewer coyotes in Torrance now than before the program began.
The science shows that lethal control simply doesn't work. What does work is removing attractants and implementing a strong public education program. Pasadena has a history of coexisting respectfully with wildlife. Setting snares in and around the Arroyo will endanger not only the intended coyotes but also companion dogs (who often run off-leash on the trail) and other wildlife. Coyotes are a perceived threat, when they are just trying to survive and raise their families in peace. Any coyotes who are killed will likely be snared, hoisted into the back of the trapper's truck, and gassed.
A little realized scientific fact is that coyotes fiercely defend their territory, but when one or both of a pack's leaders are removed, individuals from the surrounding area quickly fill the vacancy, sometimes increasing the density of coyotes in the area There are many humane, impactful measures that could be implemented at little or no cost to the city, including cleaning up the trash throughout the Arroyo area and beyond, providing wildlife-resistant trash cans in and around the Arroyo and elsewhere, removing fallen fruit, and directing residents to keep their domestic cats indoors (for the good of the cats and other wildlife as well) The responsible and humane thing for the city to do is to adopt the recommendations researched and written by the city's own health department.
Sincerely,
Marina Drake
1 7/17/2023
Item 9
aD-
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2 McMillan, Acquanette (Netta)
Subject:FW: COYOTES - re: today's 7/17/23 meeting
From: Pam Pierson Voorhees
Sent: Monday, July 17, 2023 1:37 PM
To: PublicComment-AutoResponse <[email protected]> Subject: COYOTES - re: today's 7/17/23 meeting
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Hello,
I'm a resident of Altadena - just a few short blocks from the border of Pasadena. I'm very concerned about and against the proposal to control wildlife/coyotes through lethal removal.
Like all wildlife, coyotes only know 'habitat', not boundaries from one city or street to the next. It's not up to humans to interfere with another species' ecosystem and way of life, unless there is imminent danger to human life, of course.
If pets are a concern, then it's up to their human guardians to keep them safe: inside the home when not attended by a human outside - this is no different than keeping a child safe. Pets are dependent upon their human guardians to look out for their welfare; it's our responsibility. Wildlife does not need to honor fencing.
We must remember that as Homo sapiens, we are not part of an ecosystem. We have made our 'habitat' everywhere - we know no boundaries, we don't have predators, and we pollute everywhere we live and travel.
Coyotes and their prey and predators are all part of an ecosystem that keeps everything in check. Don't disrupt that natural balance through some heartless lethal control program that ultimately won't solve the problem, will make things worse and create an imbalance among species.
In addition, do you think it's humane to break up a pack? If you trap and kill a mom, what will happen to her offspring... starve? All of these creatures have feelings and experience stress. Be mindful of that when making a decision about their welfare.
Thank you,
Pamela Voorhees
Altadena, CA
1 7/17/2023
Item 9
McMillan, Acquanette (Netta)
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Karen Emanuel
Monday, July 17, 2023 1:54 PM
PublicComment-AutoResponse
ALTERNATIVE SOLUTIONS THAN KILLING COYOTE POPULATIONS
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Please work with wildlife experts to determine a safe, cruelty free, non lethal method of managing coyote populations.
Thank you,
Karen Emanuel
1 7/17/2023
Item 9
McMillan, Acquanette (Netta)
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Dominique Holy <
Monday, July 17, 2023 1:56 PM
PublicComment-AutoResponse
Do not trap and kill coyotes
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Please listen to the science!
I urge you to resort to humane solutions. Please do not trap and kill coyotes! I strongly support Option 3.
Thank you,
Dominique hloly
1 7/17/2023
Item 9
Stevenson, Garrett
Subject:FW: Public Comment for Item 9 @ CITY COUNCIL MEETING FOR JULY 17,2023 From: Cooper Kenward < >
Sent: Monday, July 17, 2023 2:29 PM
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Hello,
As a resident I would like to express my dissatisfaction with the council considering the removal of indigenous coyotes.
These animals are part of a local ecological system that makes Pasdena unique and livable, By removing these animals at the request of a small set of individuals you are not representing the community as a whole. You are merely taking orders from the loudest voice in the room.
Please consider the simpler option of educating and helping the people of Pasadena coexist with coyotes rather than wasting funds on trapping and removal.
thank you,
Cooper Kenward
7/17/2023
Item 9
1 Stevenson, Garrett
Subject:FW: Agenda Item 9 - Human-Coyote Interactions
From:
Sent: Monday, July 17, 2023 2:30 PM
To: PublicComment-AutoResponse <[email protected]> Subject: Agenda Item 9 - Human-Coyote Interactions
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RE: Agenda Item 9 - Human-Coyote Interactions
Please select Option 3 from the Staff Report and direct staff to convene a panel of coyote experts to improve our collective understanding of effective approaches. The City of Pasadena must implement a rational, science-based approach to concerns about coyotes in city neighborhoods.
The so-called coyote problem is largely a human problem. Trapping and killing won't stop conflict with coyotes. A program combining education in techniques to resolve coyote conflicts and how to discourage coyotes offers the best method for handling and preventing conflicts with coyotes and is working already in a number of communities. Pasadena is fortunate to have nearby natural areas which are home to a variety of wildlife, especially the San Gabriel Mountains and the Arroyo Seco. Some wildlife even thrives in the vegetation of freeway rights-of-way.
Many years ago, I lost a well-loved cat to coyotes—weather was hot and I couldn't persuade the cat to come in the house at night. Therefore, this predation was part of the "human problem". My current cat is "indoors only".
Please choose a rational, science-based solution rather than an emotional response to the presence of coyotes in our city.
VOTE YES for OPTION 3 from the staff report.
Genette Foster
Council District 2
7/17/2023
Item 9
1 Stevenson, Garrett
Subject:FW: Council's Agenda Item Regarding Coyote's
From: Thomas Seifert < >
Sent: Monday, July 17, 2023 2:36:38 PM
To: Jomsky, Mark <[email protected]>
Subject: Council's Agenda Item Regarding Coyote's
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Mark: Please distribute the following with my thanks!
Dear Honorable Mayor Gordo and Distinguished Members of our City Council:
I have lived directly across the street from the Lower Arroyo for 45 years and have had absolutely no negative
interaction with any of our Coyote neighbors. Needless to say, I exercise good judgement and reasonable behavior.
I call special attention to the July 8th Star News editorial written by Dia DuVernet, President and CEO of the
Pasadena Humane Society. Her words speak volumes and I encourage you to follow her recommendations.
With my sincere thanks and appreciation,
Thomas Seifert
Pasadena, CA 91105
7/17/2023
Item 9
1 Stevenson, Garrett
Subject:FW: Non lethal methods and listen to science RE: coyotes From:Analise McNeill
Sent: Monday, July 17, 2023 2:48 PM
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Hello,
As a Los Angelean born and raised who works in Pasadena regularly I humbly ask you to please listen to the science and support the recommendations being made by staff (option 3) to gain a better understanding of Pasadena's coyote population in order to best prevent conflicts between humans and coyotes. Please do not resort to trapping and killing as that can have unintended consequences and actually INCREASE coyote population.
Wider education may be needed for how to "haze" coyotes and also that it is unsafe to leave pets outside unattended. Please do not kill our neighbor coyotes they serve an important role in our ecosystem and are just trying to survive as we are. There are better science backed methods that will be more successful and humane!
Thank you for your time and serving Pasadena,
An a Use
Analise McNeill
"Do what you can, with what you have, where you are." -Theodore Roosevelt 1 7/17/2023
Item 9
Stevenson, Garrett
Subject:FW: Council meeting item 9: concerns related to human-coyote interactions From: Calandra Cherry < >
Sent: Monday, July 17, 2023 2:54 PM
To: PublicComment-AutoResponse <[email protected]> Subject: Council meeting item 9: concerns related to human-coyote interactions !Some people who received this message don't often get email from. Learn why this is important ^] CAUTION: This email was delivered from the Internet. Do not click links or open attachments unless you fcnowthe content is safe. Report phish using the Phish Alert Button. Learn more....
Hello,
My name is Calandra Cherry and I would like to submit a comment in support of protecting Pasadena's coyotes. While I understand that some citizens may have had interactions with coyotes ranging from undesirable to tragic if resulting in the death of a pet, lethal action is not the answer. Coyotes are partof the ecosystem, one that is already damaged, fragmented, and fragile largely due to human encroachment. These animals happen to be very intelligent and adaptable, which enables them to continue to thrive in urban and suburban environments. This is something I personally admire about them, and not something that should be punished. Instead, if the city simply makes the effort to utilize wildlife experts and educate the public, and makes resources accessible for people to modify their properties and habits in order to reduce human-wildlife conflict, we can coexist with our local fauna and preserve what makes Pasadena and neighboring towns special. Our behavior shapes their behavior, so we can therefore change our ways that have created these negative circumstances and create better outcomes. The removal of a natural predator like coyotes would only create more ecological problems that we would also need to rectify, digging us deeper into a hole of irreparable ecological damage. Please, I urge the city to do the right thing, and the humane thing- do not start a coyote manhunt and further vilify an animal that is just living life where they belong; make positive change and be a role model for the entire LA metropolitan area by providing education to the public and practical resources for citizens to keep themselves, their pets, and wildlife safe. Thank you.
Sincerely,
Calandra Cherry
7/17/2023
Item 9
1 Stevenson, Garrett
Subject:FW: Coyotes: no trap and kill
-—Original Message-—
From: Kerry Pearce < >
Sent: Monday, July 17, 2023 3:12 PM
To: PublicComment-AutoResponse <[email protected]> Subject: Coyotes: no trap and kill
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Hi
Trap and kill doesn't work to mitigate the coyote "problem". Whether you come at it from a humane or fiscal angle, it makes no sense. Why not trap and kill skunks? They are a more vexing problem to me than coyotes. Firmly in opposition to this idea!
Thanks for listening,
Kerry Pearce
1 7/17/2023
Item 9
Stevenson, Garrett
Subject:FW: Urban coyotes
-—Original Message-—
From: John Hazlet< >
Sent: Monday, July 17, 2023 3:18 PM
To: PublicComment-AutoResponse <[email protected]> Subject: Urban coyotes
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Coyotes play an important ecological role in rural areas. In the city they are pests that kill small pets for food and threaten small children. We have no shortage of them in our 91104 neighborhood. Within the past few days we have seen a family of five coyotes (two adults and three pups) running down the street; one snoozing in our front garden (photo a available) and a couple of starving mangy pups hanging around the yard. They need to be trapped and killed - not moved to rural areas where they'll just stroll back into the city.
Sent from my iPhone
7/17/2023
Item 9
1 Stevenson, Garrett
Subject:
Attachments:
FW: City of Pasadena Coyote Management Public Comment
connolly-study.pdf; favicon.ico
From:
Sent: Monday, July 17, 2023 3:57 PM
To: PublicComment-AutoResponse <[email protected]> Subject: Re: City of Pasadena Coyote Management Public Comment I Some people who received this message don't often get email from. Learn why this is important ^\] CAUTION: This email was delivered from the Internet. Do not click links or open attachments unless you frnowthe content is safe. Report phish using the Phish Alert Button. Learn more.
My name is Kristy Brauch Clougherty. I am a certified UCANR California Naturalist and UC Cooperative Extension Master Gardener trained in Integrated Pest Management. I strongly stand against the trapping, removal, and or culling of coyotes for population management. Research details strong evidence that reducing the number of coyotes results in a higher population unless 75% of the total coyote population is culled annually. Pasadena is an urban wildlife interface and significant reduction in coyotes would have a damaging effect on other wild animals in the food chain. Coyotes play an important role in pest control. They are a natural predator of rodents and small mammals considered pests.
Pasadena is not experiencing an increase in coyote population, but rather and increase in the number of residents that live in the wild urban interface. For this reason, I strongly encourage the City of Pasadena to put effort into educating the public about coexisting with coyotes that are a natural part of the landscape. Residents should learn to change their habits that attract coyotes to neighborhoods by keeping pets like cats and small dogs indoor or on a leash and their food indoors, remove fallen fruit, keep garbage in a secure bin, and clear heavy vegetation. I urge the City of Pasadena to use a research based approach in all aspects of wildlife management.
Coyote / Home and Landscape / UC Statewide
IPM Program (UCIPM)
ipm.ucanr.edu
7/17/2023
Item 9
1 LL:181708841
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Volume; 1872
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Year: 1975
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Journal Title: Bulletin - Division of Agricultural
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Article Author: University of California (System);
United States G.E. Connolty & W.M. Longhurst
Article Title: The effects of control on coyote
populations: A simulation model
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.WtVERStIY LIBRAE
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THE EFFECTS OF CONTROL
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Division of Agricultural Sciences
UNIVERSITY OF CALIFORNIA
PRINTED AUGUST 1975
BULLETIN
1872
COOPERATIVE EXTENSIONUNIVERSITY OF CALIFORNIA
This intormation is provided by Cooperative Extension, an educational <K)ency o( (he University of California and the United Stales Ocpartmontof Agriculture.
Support for Cooperative Extension is supplied by federal, state, and county governments. Cooperative Extension provides the people of Califainia wilh the latest scientific information in agriculiure and family consumer sciencn. It also Sfionsors (he 4 H Youth Program.
Cooperative Extension representaiives, surving 66 counties in California, are known as fain, home Of youth advisors, Their offices usually are located in the county scat. They will be liappy tu provide you with information in their fields of work.
Cover p/iofo credit:
V. S. Fish and Wildlife Service,
Department of the Interior
The Univrtity o( Catifomia't Coop*rotiv Exlention ptogramt aro availoklt to oil, without rogard to rac», color, or national origin.
Itlued in furtherance of Cooperative Extension warlt, ocl* of May S end June 30, 1914, in cooperotion with ^ha Unitod State* Oapnrtmant o( Agriculturt, Jomat B. Ktndrick, Jr., Oicclor, Cooperottva Extaniion, Univcr'sity of Calilorni'ia.
THE EFFECTS OF CONTROL ON COYOTE POPULATIONS: A SIMULATION MODEL1'2 Guy E. Connolly, Staff Research Associate, Division of Wildlife and Fisheres 3 Biology, University of California, Davis'
William M. Loiighurst, Wildlife Biologist, Division of Wildlifa and Fisheries Biology, University of California, Davis
ABSTRACT: According to a model developed to simulate coyote population dynamics, the primary effect of killing coyotes is to r&duce the density of the population thereby stimulating density-dependent changes in birth and natural mortality rates.
Tests of varying levels of control kills showed that a coyofce population can maintain itself and even Increase its numbers except at the very highest levels of control. If 75 porcent of the coyotes are killed each year, the population can be exterminated in slightly over 50 years.
Birth control combined with killing coyotes directly reduc&d both the breeding and maxiraum populations more than when either method was used separately. However, birth control is not yet feasible for field operations.
In this model, coyote populations reduced by intensive control recovered to precontrol densities within three to five years after control was termi- nated. Under current conditions, considering the restrictions placed upon control methods, coyote densities probably cannot be significantly reduced except in limited g&ographical areas.
The yearling pregnancy rate and the mean litter size are probably the best criteria for indicating the level of control, although the proportion of yearlings in the breeding population, the proportion of pups in the control kill, and the ratio between the control kill and breeding population also vary with the intensity of control.
Coyote control data from Mendocino County, California, we.rs compared with the model output. The existing county control program does nat appear 1 2
3 'Submitted for Publication April 30, 1975.
A contribution from Western Regional Research Project W-123, Evaluating Management of Predators in Relation to Domestic Animals. 'Present address: U. S. Fish and Wildlife Service, Ti^in Falls, Idaho 1 to affect overall coyote numbers but locally it may be stimulating the rate of reproduction,
INTRODUCTION
Killing coyotes, primarily because they prey on livestock, has been widely practiced in the western United States for many years. Tremendous sums have been spent on trapping, poison bait programs, shooting, den hunting, the Humane Coyote Getter, and M-44 devices (Cain, et^ al. 1972). Control objectives have apparently shifted from extermination (Adams, 1930}, to population reduction ("prophylactic control"), to selective removal of problem animals (Cain, et al., 1972). In addition to the federal control program carried out by the U.S. Fish and Wildlife Service and its cooperators, fur trappers and sport hunters take many coyotes. In California alone sport hunters are estimated to take over 80,000 coyotes annually (Swick, 1974).
However, coyote numbers seem to be increasing over much of the West (U.S.
Congress, 1973; page 58) in spite of all these efforts.
Considering this history it is logical to wonder what the effect of control actually is on coyote populations. Cain, et al. (1972) questioned whether control activities influenced overall coyote deiisities in some states even when 1080 (sodium monofluoroacetate) poison stations were conmonly used.
Young and Jackson CL951; page 156) have described the effectiveness of trapping and poisoning "like digging a hole in the ocean." Detailed study of this natter has been surprisingly limited in relation to the magnitude of the control effort.
This paper describes the development and use of a simple simulation model to examine the probable effects of control on coyote populations.
DESCRIPTION OF THE SIMULATION MODEL
In this model the population consists of a seasonally variable number of coyotes. Uatural coyote populations are of the "birth-pulse" type, with births occurring at one season while deaths occur the year round (Gier, 1968; Knowlton, 1972). Numbers are lowest after the breeding season (just before the birth pulse) and highest just after the birth pulse. W& have simulated the annual population cycle in three steps: births, control mortality, and natural mortality l^?hich includes all other types of mortality. In effect, the take of coyotes by sport hunters and fur trappers Is additive to the number t
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2 of coyot&s killed by federal, state, county agencies or private individuals to alleviate livestock depredations. For purposes of this model all of these forms of coyote removal are lumped together under control mortality. It should be realized, however, that sport hunting and fur trapping are non- selective in their removal of coyotes from the population whereas coyote killing Co alleviate livestock losses tends to be focused on localized problem areas and on individual "Id-ller" coyotes. The coyoces remaining at the end of the year constitute the breeding population for the next year. These events are related schematically in figure 1.
Our simulated population differs from actual populations in several respects. For example, we describe the minimum population (just before whelping) as the breeding population. Actually the population at breeding might be substantially higher than the minimum population, depending on natural and control loss during gestation. In this model, breeding is significant only in terms of the numbers of pups born, and this is a function of the minimum population.
As noted above, we have simulated the annual coyote population cycle in three steps: births, control mortality, and other "natural" mortality.
Though in reality all forms of mortality may occur throughout the year, considerable abstraction from this pattern was needed in the model to keep the calculations within reasonable limits. In each year the control kill numbers are taken from the maximum population. Natural losses are then cal- culated for the aniinals surviving control. The justification for this is that intensive control, in the form of den hunting, often is applied to the maximum population. If pups are not killed in their dens, survival is thought be .be liigh until fall (Knowlton 1972). In the model, both control and natural losses are calculated once each year. The whelping season also is compressed into a single calculation each year, even though in nature it may last several weeks.
In our model toro forms of human intervention C"cont;c°l ) in t^le coy°te population are considered: coyotes may be killed or females may be prevented from having pups through the use of chemosterilants. Either or both forms of intervention may be applied in any combination of rates. In the absence of 'control," the model simulates the d^amics of a population that is affected only by natural losses. The control kill and birth suppression 3 CD
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4 rates are specified arbitrarily by the investigators at the beginning of each run (or at the beginning of each year if desired). Reproductive and natural loss rates are generated within the model and are variable vrith coyote density, as described in detail later.
This coyote model may be called an "if-then" simulator. That is, if a specified set of initial conditions is true, then over tima a certain set of results will follow. If a specified control level is pursued over time the population will eventually stabilize at a level different than that when no control is practiced. Various population parameters can then be compared with similar values from an uncontrolled population to infer the effect of that level of control on the coyote population. The concepts of this model are generally similar to those employed by us in a deer simulation model (Anderson, e^ al., 1974).
This model is an abstract representation of a complex biosystem. Like any other model it is a simplification of real phenoraena and requires certain assumptions. Some of these assumptions are Iny licit in figure 1. Others follow:
(1) In the absence of control, the population is stable, both in numbers and age structure. The population occupies an area of unspecified size which has sufficient resources to sustain a breeding population of Just 100 coyotes each year. For simplicity the carrying capacity of this area for coyotes is assumed to be constant year after year. In reality, the carrying capacity varies with climate, food supplies and other factors beyond the scope of this model.
(2) In the model the population contains two age classes: pups (from birth to 12 months of age), and adults (over 12 montlis old). As the whelping season approaches, the pups of the previous year are called yearlings to distinguish them from the newborn pups.
(3) Adult recruitment is limited to pups which survive their first year. Immigration and emigration either do not occur'or occur at equivalent rates.
(4) Birth and death rates are constant for adult coyotes of all ages. 5 (5) The sex ratio of both pups and adults is 50:50.
(6) There is no sex-specific mortality; i.e., natural and control losses consist of equal numbers of males and females, both among pups and adults.
(7) Control loss rates apply to the maximum population. Natural loss rates apply to the coyotes surviving control.
(8) Each run begins with 100 coyotes at breeding time, 60 adults and 40 yearlings. (The reason for this age composition is given in the description of the natural mortality functions.)
The coyote population model diagrammed in figure 1 represents a set of variables relat&d to ona another by simple functions and difference equations.
The variables and their infcerrelatlonships are listed in table 1. For details of programming and calculations see Appendix.
BIRTH AND NATURAL LOSS FUI^CTIONS
We believe that birth rates are higher and natural loss rates lower in an intensively controlled coyote population than in an uncontrolled population.
Vo. agree with the concept that intensive population reduction alleviates the constraints that ordinarily lim.it numbers in an uncontrolled population, In our view these constraints (densifcy-dependent variables) consist most Importantly of intraspecific competition for limited resources, primarily food. Liksi^ise competition for other habitat resources, such as favored denning sites, zaay increase with density and serve to limit reproductive success. Social stress in relation to density may also have a bearing in this regard as would transniission of diseases and parasites. Wliatever the sp&cific natural limiting factors are, it is known that both pregnancy rates (Gier, 1968) and litter size (Knowlton, 1972) vary with control intensity and environmental conditions. While environmental conditions for coyotes may be influenced by weather or land use practices, intensive control also appears to enhance environmental conditions for the surviving coyotes. As explained by Henderson (1972). . . "reducing the numbers of predators makes it easier for the remaining predators to survive the wliiber and come through in better shape."
While it is accepted that control can induce increased birth and natural survival rates in coyote populations, the magnitude of these effects at 6 various control Intensities has not been fully determined. However, in this model it was necessary to mathematically define these functional rela- tionships. Since it would have been impossible to identify and separately quantify each environmental factor affecting births and natural losses, the relative density was used as a proxy variable encompassing all the density dependent effacts. The relative density Is simply the number of coyotes in the population expressed as a fraction of the number which would have been present in the absence of control. When no control is practiced the relative density is one, and birth and natural loss rates are unchanged.
As the population is reduced by control, the relative density is also reduced, causing corresponding changes in the birth and natural loss rates which are functionally related to relative density.
Five parameters in this model vary with relative density: the pregnancy rates for adult CBa) and yearling (By) female coyotes, the average litter size (L), and natural mortality rates for adults CNa) and pups (Np).
Detailed descriptions of the functions follow;
Adult pregnancy ra^e_QBal
It has been shown that 60 to 90 percent of the adult female coyotes produce litters (Gier, 1968; Knowlton, 1972). For this model all coyotes older than yearlings C12 months of age when pups are born) are considered to be adults. We assume that, in the average year, 70 percent of the adult females produce litters in an uncontrolled population (relative density3 1), and that this pregnancy rate increases to 90 percent as the population is reduced by control to half the precontrol density Cfig< 2), We take 90 percent as the biological limit for this parameter, so the adult pregnancy rate remains at 90 percent for all relative densities below 0.5. The adult pregnancy rate function from D1.0 to D^ '= 0.5 is described by the equation:
Ba = 1.1 - 0.4 D1
which was calculated by least squares regression techniques.
Yearling pregnancy rate (By)
The fraction of yearling female coyotes bearing litters may range from 0 to 70 percent (Gier, 1968). Breeding yearlings are those which bear pups at about 12 months of age. We suggest that in an uncontrolled population 7 Figure 2.
PROPORTIONS OF FEMALE COYOTES BREEDING !N RELATION
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Published estimates of average litter size range from 2.8 to 8.9 pups per litter (Knowlton, 1972). However, litters of 12 or more pups are not uncommon. Wade C1975) records 16 litters containing 154 pups taken by Benton hitman in Yakima and Columbia counties, Washington, in 1955, for an average of 9.6 per litter.
We propose an average litter size of 4,5 in an uncontrolled population (D^ ^ 1.0), increasing to 9 pups per litter as the population is reduced to half the precontrol density CFigure 3). With 9 set as the maximum for this parameter, the litter size remains at this level for all relative densities below 0.5. The relationship from D,'11.0 to D, = 0.5 is given by the equa- tion L= 13.3 - 9 (D,), wliich was also calculated by least squares procedures Relative density (D,, D^)
In this model the birth functions are based on relative density at breeding (D,). This relates breeding success to the density dependent constraints operative at the time of breeding. Because the breeding portion of the uncontrolled population always contains 100 coyotes, the denomina- tor for calculating D^ is always 100 (table 1).
For mortality calculations, a different reference point was needed for relative density. Both pups and adults die, but only the animals surviving control are susceptible to natural mortality. The relative density after control (D^) is based on the numbers of animals susceptible to natural mortality. As this value is 203.5 coyotes each year in the uncontrolled population, the denominator for calculating D^ is always 203.5 (table 1).
Adult natural mortality CNa)
Knowlton (1972) estimated that In the absence of control the annual mortality rate was about 40 percent, W& feel that this rate will decline 9 Figure 3.
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Table 1. Variables for the coyote population dynamics model.
VariableSymbolRelation to other variables
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<fr
Yearling coyotes at breeding Cy
Adult coyotes at breeding Ca
Minimum (breeding) population Cb
Relative density at breeding D,*
Proportion of yearling females By
with litters
Proportion of adulL females Ba'
with litters
Breeding females (number with Fl
litters)
Proportion of breeding females S
suppressed
Litter size L
Pups born P
Proportion of pups produced by Py
yearling females
2-1aximum population Cm
Proportion of coyotes killed K
in control
Pups killed by control' Pk
Adults killed by control Ak
Total control kill Kt
Proportion of pups in control Kr
kill
Control kill as proportion of Kb
breeding population
CyCt) = P(t - 1) ~ Pk(t - 1) -
Pn(t - I)
Ca(t) = CbCt - 1) - AkCt - D -
AnCt ~ 1)
Cb = Cy + Ca
D^ = Cb/100
By ° fD^
Ba = fD
Pl = 0.5(1 - S)(ByCy + BaCa)
Specified by investigator
L = fD^
P = L (Pl)
Fy = (0.5L)(1 - S)CByCy)/P
Cm = Cb +F
Specified by investigator
Pk = P(K)
Ak = Cb(K)
Kt = Pk+ Ak
Kr = Pk/Kt
Kb = Kt/Cb
*D, expresses the breeding population as a fraction of the br&eding population in the absence of coritrol.
These values increase as D- decreases. The functions ar& described in Figures 2 and 3.
'Assumes a 50:50 sex ratio at breeding.
11 Table 1. Ccontinued)
VariableSymbolRelation to other variables
Y
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g
Relative density after control D,
Proportion of pups dying of Np
natural causes
Proportion of adults dying of Na'
natural causes
Pups dying of natural causes Pn
Adults dying of natural causes An
Total natural mortality Nt
Pups at year end CyCt + 1)
Adults at year end CaCt + 1)
Total year end population Cb(.t + 1)
D2(Cm - Kt)/203.5
Np = fD
Na = fD
Pn " NpCP - Pk)
An " Na(Cb - AlQ
Nt = Pn+ An
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Fn(t)
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An(t)
Cb(t + 1) " Cm(t) - Kt(t) -
Nt<t)
D^ expresses the population surviving control CAlso = population susceptible to natural losses) as a fraction of the maximum population In the absence of control.
These values decrease as D^ decreases. The functions are described in Figure 4.
as the population is reduc&d Z>y control but it will never ba lower than 10 percent. For the purpose of this model we set the adult natural mortality rate at 40 percent in the uncontrolled population CD^ = 1.0), declining toward 10 percent as D^ approaches 0 (fig. 4). The relationship Na = 0.1+0.3 (D^) was calculated using least squares regression techniques.
Pup natural mortaltty (Np)
For fche uncontrolled coyota population (Po ° 1.0), this rate was calculated from the assumptions and rates for other parameters given previously. It is apparent that in a stable population with no control, the pup natural mortality.rate can b& calculated from the number of pups born and the number of pups surviving to one year of age:
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14 .Np = (P - Cy)/P CSymbols defined in table 1.)
As previously stated, this model assumes a breeding population of 100 coyotes each year in the absence of control (assumptions 1 and 8*). If the adults are replaced solely by pups surviving to be yearlings (assumption 3), and the adult mortality rate is 40 percent CKnowlton, 1972), then short yearlings must comprise 40 percent of the breeding population. Therefore) Cy = 40.
The number of pups born depends on the number of breeding females and the average litter size (P =• L x Fl, table 1). In a breeding population of 60 adults and 40 yearlings with a 50:50 sex ratio (assumptions 8 and 5), there are 30 adult females and 20 yearling females. If 70 percent of the adult females and 10 percent of the yearlings produce litters, as estimated in figure 2 (D, = 1.0), the uncontrolled population contains 23 breeding females. If the litter size is 4.5 (fig. 3, D, = 1.0), the number of pups born (F) is 103.5. From these estimates, in the uncontrolled population Np - (103.5 - 40)/103.5 = 0.614.
This estimate differs from the value of 0.67 proposed by Knowlton (1972) primarily because we used separate pregnancy rates for yearling and adult females, while Knowlton used one value for all females.
As in the case of adult natural mortality, we feel the natural loss rata of pups \ri.ll decline as the population is reduced by control but will never be under 10 percent. For the pup natural.mortality function (fig. 4) we set the value in the uncontrolled population (D^ = 1.0) at 0.614, as calculated above, declining toward 10 percent as D^ approaches 0. The resulting func- tion is described by the equation Np = 0.104 + 0.51 (D^) as calculated by least squares regression techniques.
Discussion of birth and death functions
The functions shown in figures 2 to 4 are the most important variables in this model. We reemphasize that the form of these functions is largely speculative, although each is based on the best availabla data. During the formulation and validation phases of model development, the functions were changed several times. It became apparent that minor changes would not alter our conclusions significantly. Although additional research is ^Refer to numbered assumptions on page 5.
15 needed to define the functions more precisely) the model is so constructed that improved or refined functions can be substituted for the present ones,
CONTROL KILL RATES
Coyote pups are thought to .be less wary than adults and therefore more likely to be taken by trappers. With this in mind, our model allowed pups and adults to be killed at different rates. Theoretically, pups and adults could be killed at any coiubination of rates. To limit the number of combina- tions simulated, we sought to take pups and adults in the proportions actually expected in operational control programs. Wade (personal communica- fcion)*indicated that as the intensity of control increases, the proportion of pups in the total control kill also increases. Considering all methods of direct control efforts, pups would be expected to comprise little more than half of the kill at low control levels. Under the most intensive control as niany as 80 percent of the coyotes taken might be pups. We found that by taking the same percentages o£ pups and adults present in the population, the composition of the control kill changed as expected when the intensity of control was increased. Tills is attributed to the increase in the birth rate as the intensity of control increased. After it became apparent that different kill rates for pups and adults would not be needed, the program was simplified to apply a single kill rate to both pups and adults.
EFFECTS OF CONTROL ON THE SIMULATED COYOTE POPULATION
Figure 1 shows the two kinds of human intervention or "control" that nay be applied to coyote.papula lions — birth control or direct killing. we have tested the impacts of both kinds of control, both singly and in combination.
The general response of our simulated coyote population to control illustrat&d in table 2. Each run began with a previously uncontrolled population of 100 coyotes at breeding. As control was applied in the first year coyote numbers were reduced, causing compensatory changes in birth natural loss rates in subsequent years. If the control ld.il was held year after year at a constant percentage of the population, as shown In table 2, the population, stabilized within, a few years at a lower density than was tk£ ca.se. in the absence of control. This occurred regardless of which form i
*D. A. Wade, Extension Wildlife Specialist, Animal Damage Control, University of California, Davis.
16 of control was practiced. If the ki.il or birth control rate changed from year to year the population d£d not stabilize, but fluctuated in response to the variable control in effect. If the level of control exceeded the capacity of the population for compensations in birth and natural loss rates, the population did not stabilize but declined toward zero.
Under field conditions it is rare for exactly the same rate of control to be achieved from year to year; the population therefore, does not stabilise.
Likewise the carrying capacity of the coyote habitat may change from one year to the next, and this also prevents stabilization of numbers. the effects of killing coyotes on the population were studied by a series of runs ranging from no control to 75 percent annual control kill Ctable 3). The values shown are at stability, when the previously uncontrolled population had fully responded to the control level under test. (See years 9 ho 11 in table 2, for example.) In table 3 each value representing a specific number of coyotes was rounded to the nearest whole number. For this reason, some of the numbers do not cross check.
. As shown in table 3, killing coyotes affects ever^' variable of fche coyote population. Some parameters were affected more than others. As the percentage of coyotes kill&d annually increased, the breeding population (Cb) decreased, while the maximum population CCm) Increased slightly due to increased numbers of pups (P) born. As the control kill (Kt) increased natural losses (Nt) decreased. The effects of population reduction on the proporE.lon of females breeding CBy,Ba)> litter size (L), and natural loss rates (Np,Na) were forecast in figures 2 to 4, buL are reiterated so that results can be analyzed.
One variable which changed only slightly with control intensity was the number of breeding females CH). This resulted from increased propor- tions of females breeding CBy,Ba) as the breeding population (Cb) was reduced. Knowlton (1972) pointed out that the greatest adjustments in productivity of local coyote populations may result from variations in the percentage of yearlings becoiaing sexually mature. In our model this is simulated by the proportion of yearling females with litters (By).
However, the relative frequency of yearlings in the breeding population (Cy/ Cb) also increases with control intensity. The net contribution of yearling females to reproduction is given by Py, the proportion of pups produced by 17 9
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18 yearling females. This value ranged from less than 10 p&rcent in the uncontrolled population to almost 75 percent before an extinction level of control was reached. For this reason we concur with Knowlkon (1972) that the greatest potential for increased reproduction lies v?ith the yearling age class.
Several authors have descriled the seeming futility of attempting to reduce coyote numbers by killing coyotes 0?oung and Jackson, 1951; Cain, et^ ,al., 1972; Henderson, 1972), In table 3 perhaps the best indication of this is Kb, which expresses the annual control kill as a fraction of the breeding population. A value of 1.0 for tills parameter means that the annual control kill equals the breeding population. Note that a kill of about: three coyotes fpr every animal at breeding would be n&eded to hold the breeding population (Cb) below 50 percent of the pre-control level. Even if this figure is not precise it is apparent that a very high kill rate is needed to eliminate coyotes.
Our model suggests that coyotes through compensatory reproduction can withstand an annual control level of 70 percent, but not 75 percent. However, even at the 75 percent control level, the population persisted more than 50 years. We must point out that to achieve these results, 75 percent of the coyoles must be removed in aach and every year, 1'Than 75 percent were taken in four of every five years, t'ri.th no control in the fifth year, the breeding population (Cb) fluctuated between 28 and 76 coyotes with an av&rage of 42 and the control kill (Kt) averaged 102 animals per year.
EFFECTS OF BIRTH SUPPRESSION ON THE COYOTE POPULATION
Limiting coyote numbers by inhibiting reproduction with antifertility agents rather than killing them directly is an attractive idea, at least in theory. As pointed out by Falser (1964, page 356), "It may be more practical to prevent animals from being born. than to reduce their numbers after they are partially or fully grown and established in a secure environment." Suppressing reproduction might also prevent the comensating increase in reproduction associated with Id-lling coyotes. Most importantly, antifertility agents might be more acceptable to the public than large scale coyote killing programs, especially if people were adequately informed on the biological facts about coyote populations,
19 If an ideal birth control (chemosterilant) chemical or combination of chemicals could be developed, one dosage would sterilize either males or females for life. However, the chemosterilants tested to date are effec- tive only on females during a short period in the breeding cycle and they must receive dosages each year. Likewise we did not concern ourselves with the problems of bait distribution or Environmental Protection Agency regis- tration of the chemicals.
In this model we have examined the effects of birth suppression in a series of runs in which from 0 to 95 percent of the normally breeding females were prevented from having litters (table 4). No other form of control was practiced. All values representing coyote numbers were rounded to the nearest whole number. For this reason some of the numbers in table 4 may not cross check,
The effects of birth suppression on the coyote population diff&red in several respects from the effects of killing coyotes. As the intensity of birth suppression increased, the breeding population (Cb) declined slightly (up to S = 0.6)i, but the number of pups born (P) dropped nearly 50 percent (table '')). These results contrasted sharply with the effects of increasing the control kill (table 3) , which caused a marked decline in the breeding population (Cb) but an increase in the number of pups born (P). The net effects of these differences were that the maximum coyote population (Cm) declined with increased birth suppression (table 4) but increased with the control kill (up to K = 60 percent, table 3).
We believe the key to the different population responses to these two kinds of control is the reproductive potential of young females. As shown in table 3, tha proportion of yearlings (Cy) in the breeding population (Cb) increased with the control kill* The percentage of females with litters also increased, with the potential of yearlings (By) greater than that of adults (Ba). The composite affect of these variations is that the proportion of pups produced by yearling females (Py) increased with the control ld.il.
Turning again to the results of birth suppression Ctable 4) , we see that Py is virtually constant at all levels of suppression. Not only does the proportion of yearlings In the breeding population (Cy/Cb) decline as S increases, but the increase in the proportion of yearliiigs breeding (By) is 20 Table 4. Simulation of affects of birth suppression by cheniosterilants on a coyote population.
Variables*
PERCENTAGE OF BREEDING FEMALES
SUPPRESSED ANNUALLY (S)
02040608095t
Cy
Cb
By
Ba
Fl
L
p
Py
Cm
Kt
Np
Na
Nt
40.00 100,00
0,10
0.70 23.00
4.50 104.00
0.09 204.00
0.00 0.61
0.40 104.00
—Annual
37.00 99.00
0.11 0.70
13.00 4.50
87.00 0.08
186.00
0.00 0.57
0.37 86.00
values at
34.00 97.00
0.14 0.71
15.00 4.80
71.00 0.10
168.00
0.00 0.53
0.35 71.00
population
29.00 92.00
0.20 0,73
10.00 5.30
54.00 0.11
146.00
0.00 0.47
0.32 54.00
stability————
21,00 5.00
79.00 32.00
0.36 0«70
0.79 0,90
5.00 1.00
6.40 9.00
34.00 6.00
0.14 0.13
113.00 39.00
0.00 0.00
0.39 0,20
0.27 0.16
34.00 6.00
^
^
^
*For explanation of symbols sea table 1.
Population declined slowly aft&r year 20 but appeared
Values sho^m are for year 50-
'Values generated in model exceeded and therefore were
maximum values.
stable by year 50.
replaced by specified
21 limited because the 'breeding population remains near pre-control levels.
Birth suppression thus provides a "dou'ble-barrelled" effect, directly limiting the maximum population (Cm) by restricting the number of pups born (P)> and indirectly preventing increased breeding by young females by restricting the relative numbers (Cy/Cb) and breeding success (Cy) of yearlings.
Livestock losses to coyotes are said to be particularly serious during spring and summer because of the food requirements of the pups (Wade, 1973).
In this connection the birth suppression approach is particularly attractive because it reduces the number of pups born and presinnably the depredations associated with the feeding of pups < In contrast, increased killing of coyotes might actually increase depr&datlons near den sites» as the niimber of breeding females (Fl) remains nearly constant while the litter size (L) increases with the control kill Ctable 3)-. The. critical relatioiiship Bay be the level of competition for available food resources in relation to coyote density.
Since birth suppression offers real advantages over more traditional means of coyote control, it is unfortunate that this approach has not yet been perfected to the point of field application. While initial trials were promising (Balser 1964)s later tests were less successful CLinhart, ^£a^,» 1968). The main constraints appeared to be coiisumption of baits by nontarget animals, many coyotes are not exposed to baits, and the drug used, diethylstilbestrol» is only effectiva in the feinale coyote for a limited period* There may be hope for future developments, but at present birth control is not a viable alternative to existing control methods.
THE EFFECTS OF INTEGI^ATED CONTROL (BIRTH SUPPRESSION + KILLING)
ON THE COYOTE POPULATION
It seems unlikely that birth control will supplant conventional methods of coyote control^ at least in the near future, and even with an effective birth suppression program it is likely that some coyotes would still have to be killed in chronic depredation areas. Therefore, we have tested the effects of Id-lling and birth control combined (table 5). The two kinds of control might be applied in any combination of rates, but in table 5 the alternatives are limited to equal percentage rates for both kinds of control 22 within each run. As in previous tables the values representing numbers of coyotes were rounded to the nearest whole number.
In general, the results of integrated control are intermediate between those obtained with either birth control or killing applied separately.
Integated control (table 5) reduced the breeding coyote population (Cb) more effectively than when either control method was applied separately (tables 3 and 4). However, the consequences of reducing the breeding population include increased productivity of yearling females (By) and Increased litter size (L), which lead to more pups born CF) under integrated control (table 5) Lhan would be the case with birth control only (table 4). There appears to be a trade-off relationship between the breeding population (Cb) and number of pups born (P), in that it is hard to minimize both parameters simultaneously. The breeding population can be reduced by a heavy control kill, but at the cost of increased reproduction and increased maximum popula- tion. Conversely, the ni-unber of pups produced (P) can Ie reduced most by birth control in a breeding population kept as large as possible. Of the strategies tested so far in our model, the best prospect for reducing both breeding and maximum populations would be integrated control at the highest practicable rate. . . .^ ........ . .. . .......... .. .. . .. .. .
RECOVERY OP COYOTE POPULATIONS FROM CONTROL
One aspect of coyote population dynamics which has received little study is the capacity of a heavily controlled population to Increase after control is terminated. This was simulated for two different levels of control — 50 percent and 75 percent annual control kill for 20 years — followed by as many years without control as were required for the population to recover to the precontrol level. The response of the breeding population (Cb) to these treatments is shown in figure 5.
The population from which 50 percent of the. coyotes were removed annually stabilized after 6 years with a breeding population CCb) of 72, coyoLes each year. Other parameters of this controlled population at stability are given in table 3 (K = 50 percent). After control was terminated the population recovered to its precontrol level in 3 years (fi-g* 5). By the beginning of the fourth year after control was stopped, the numbers of yearlings and adults in the breeding population were similar to those in the pre-control population.
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25 Previously we noted that coyotes would be exterminated if 75 percent were killed each year (table 3). After 20 years at this leve.1 of control the breeding population was reduced to nine coyotes (fig. 5). Hcnvever, in our model the response to cessation of control was rapid. The breedingpopu- lation regained the precontrol density by the end of the fifth year after control was terminated. If this projected recovery rate. is accurate, there is no need for concern that the coyote may become a rare or endangered species.
TIIE FEASIBILITY OF REDUCING COYOTE ITUIfBERS BY CONTROL We have sho\<nn that coyotes could conceivably be exterminafc&d if sufficient numbers are killed for a sufficient number of years. However, there is a great difference between killing coyotes in a computer and killing them in the field.
In field operations the effort needed to take each coyote increases with the intensity of control as a result of reduced density. Field opera- tions usually cannot be planned to obtain specified- percentage kill rates, but only to apply control within th& limits of available funds and manpower.
Fortunately (or unfortunately, depending upon one's point of view) it is usually beyond the range of economic feasibility to apply enough control to exterminate the coyote. Because of limited resources, predator control agencies generally concentrate their efforts in areas where depredations on livestock are most severe. This "hot-spot" control pattern leaves most of the coyotes subject to light control, so that surplus animals are available to repopulate the areas where control is 'heavy.
Animal control specialists generally agree that poisons were the most effective means of reducing coyote populations. Prior to the presidential ban (President's Executive Order Number 11643 of February 8, 1972), about 80 percent of all predatory animals killed in federal control programs were taken with toxicants (Bureau of Sport Fisheries and Wildlife, 1973). Cain, ^t aj,. (1972, page 42) reported that the use of 1080 may have caused coyote populations to decline in seven western states. The Cain committee also concluded that generalized coyote population control may be the most effective approach to reducing livestock losses. ^ataver teh desirability of such control, we do not believe substantial coyote reductions can usually be effected over broad areas without the use of toxicants. As shoi/n in tabl&s 3 to 5> coyotes will persist except with the most intensive control. 26 The techniques presently used for coyote control include trapping, the M-44 cyanide ejector device in some areas, shooting both on the ground and from aircraft, and den hunting. The relative effectiveness of these methods may differ with the intensity of control. Efforts to reduce the population by trapping or aerial shooting just before breeding would probably decline in effectivaness proportional to the decline in the breeding population (Cb) as control levels increase Ctable 3). However, the number of females with litters (Pl), and presuiaably th& nuinBer of dens, declines only slightly with increasing control (table 3). Therefore, it appears that den hunting should remain quita effective even at high rates of control. Aerial shooting has proven very effective in areas of sparse cover but cannot be relied upon in brushy or timbered areas.
As mentioned earlier, the take of coyotes in many areas by sport hunting may greatly exceed the number removed through deliberate control programs, Likewise, in some places bounties are still being paid as an incentive to kill coyotes. Considering the strong compensatory reproductive response of coyote populations to r&duction, if control, sport, and bounty hunting collectively do not reduce numbers annually on a continuing basis by at least 75 percent, no sustained declina in the population can be achieved.
Therefore, to summarize, in most situations, killing coyotes at rates below 75 percent may merely stimulate reproduction and aggravate the problem by increasing the seasonal population pressure on the food supply. With such increased competition fo.r food, it is reasonable to expect coyotes to turn more to alternative food sources such as livestock. From this standpoint chemosterilants may be especially useful if they can be applied effectively, since they do not tend to cause increased food competition.
INDICATORS OF CONTROL INTENSITY
Since reliable estimates of coyote numbers are notoriously difficult to obtain, the information needad to plan intelligent predator management programs is not usually available. In most areas we simply do not know t^Qw the control kill relates to the size of the population, or even whether coyote numbers are increasing or decreasing. However, thera are several statistics maasurabls from the control kill which can serve as indices to the level of control actually being achiaved. Perhaps the most useful of these are measures of reproductiva success.
27 Our work suggests that the proportion of yearlings in the breeding population (Cy/Cb) , the proportion of females with litters (GyaBa), tlie litter size (L), fche proportion of pups in the coiitrol kill (Kr), and the ratio between the control kill and breeding population (.Kb) all vary with the iittensity of control Ctable 3). Several of these rates can be determined by axamination of the carcasses of coyotes killed in control programs, and of the results compared with table 3 or other estimates to infer the actual control level. Probably the most indicative data would be the yearling pregnancy race (By) and the lifct&r size (L). All of these measures vary vith environmental conditions as well as control intensity. To separate ttiese influences would require sampling of uncontrolled coyote populations to establish baseliiie data for comparison with the controlled populations.
Annual samples of coyotes for a period of years would also be desirable to esttmafce the range of variability associated with year to year ctenges In environmental conditions.
Predator control admto-Lstrafcors frequently cite the number of aiiinials killed as a measure of control effectiveness. While this statistic is often the only one available, it has little meaning unless it can be related to the number of coyotes remaining ±n the population. Whenever an estimate of the breading population (Cb) is available, the control kill (Kt) may be expressed as a fraction of the breeding population to obtain a better index of control effectiveness. As notad earlier Ctable 3} this ratio (Kb) should exceed 3.0 if control is maintaining the population below half of its normal (uncontrolled) density.
COYOTE CONTROL IN MENDOCINO COUNTY, CALIFORNIA
This section describes actiial coyote control as practiced in Mendocino Counfcy and relates this control program to our model. Mendocino County was chosen as an example because of our experience on coyote studies at the University of California, Hopland Field Station within this county^ M&ndocl.no Couizty contains 3,500 square miles of rugged forest and range lands in north coastal California. Dense redwood and Douglas fir forests cover much of the coastal half of the county. The eastern half is a mosaic of grasslands oak woodland, hardwood, chaparral, and coniferous forest types« The grasay openings grazed by liv&stock are typically close to woods or 28 chapparal thickets, which provide good escape cover for coyotes. Vehicle access in many areas is restricted by the steep terrain and dense vegetation.
Approximately 20 percent of Lhe county is public land (National Forest or National Resource Land) where little livestock grazing or predator control is practiced,
About half of Mendocino County is grazed by livestock, and coyotes occur on virtually all of the livestock ranges. Coyotes have preyed on live- stock, particularly hseep, in this part of the state since the early days of European settlement. A predatory animal control program has been carried out under county auspices for the past 30 years and the area has been divid&d into six districts with a full-time hunter trapper worlcin£ "ach district.
The trappers are supervised by the Director of Animal Control. Most of the coyotes are taken by stael.traps and den hunting, but some calling employing sirens or commercial predator calls is done as well. H~44 devices were also used until banned by the executive order in 1972. Uo other toxicants have been used recently. Aerial hunting is not practical in this area because of the dense vegetation and steep terrain.
In 1973-74 the Mendocino County Animal Control Department made an estimate of the numbers of coyotes.in the countiy (Vann, personal cot.munica- tion).* Each trapper district was evaluated by sections, with the trappers giving their best estimate of the coyote population in each section. Areas not being trapped were itispectad by the Director and the numbers of coyotes were estimated from scat counts, tracks, sightings, and den numbers. The estimates for all areas were summarized for a total breeding population of about 4,135 coyotes for the entire county.
hTI-ien this estimate was made it was thought to be conservative. Director M. Vann now believes (March, 1975) that the previous estimate should be revised upwards by several hundred. Approximately 50 percent of the county, including all areas east of highway US 101, is heavily populated by coyotes and an additional 30 percent is lightly populated. Wil.ie. it is difficult to verify Vann's estimate of coyote numbers in the county, we believe it *M. Vann, Director of Animal Control, Men.docino County. 29 is reasonable and w& had independ&ntly estimated the breeding population at about 4,000 animals before learning of Vann's work.
Vann reported that although coyotes may be found throughout the livestock ranges of Mendocino County, not all of the county is subject to intensive control. Occasional den hunting or calling is dona in many areas, but only about 25 percent of the county is worked intensively. The areas of greatest coyote density, particularly public lands, receive little or no control.
Widespread, intensive predator control is not possible in this county because of limited funds and public opposition to control in excess of proven needy. Therefore, the control strategy is to concentrate on areas where livestock losses to predator's are most serious. These often are ranches adjacant to wild lands too steep or too brushy to support livestock. Such wild lands apparently serve as "coyote reservoirs," providing a ready source of animals to replace those taken by trappers from the livestock ranges nearby. Under these circumstances, the trappers take as many coyotes as possible from the inanediate problem areas. They also w^ork the "refuge" areas, particularly by den hunting, in an attempt to minimize the numbers of coyotes available co repopulate the problem areas»
The number of coyotes taken by Mandocino County trappers is quite con- stant from year to year. During the five year period 1970 to 1974 an average of 334 coyotes was taken each year. The yearly totals ranged from 303 to 363 during this period. In addition to the coyotes removed by county trappers, perhaps 50 per year are taken by deer hunters, sport hunters, and callers.
Few, if aiiy, are taken for fur. Comparing the coyote control program in Mendocmo County to the output Ctable 3) of our theoretical model, i-t is evident that the. overall control kill is quite low. Taking the estimated breeding population (Cb) of 4135 coyotes and the estimated control kill CKt) of 384 per year C334 by trappers and 50 by sport hunters) as explained above, the control kill amounts to 9 percent of the breeding population.
This kill ratio (Kb) is low in relation to the values for Kb in table 3, suggesting that the actual kill rate CK) in Msndocino County is about 5 percent of the maximum population.
In addition to the kill ratio CKb), we also determined the average coyote litter size in the county froin trappers' reports indicatitig the 30 numbers af unborn pups in pregnant females. T^venty-nine litters were reported from 1968 througli March 1975. The fetal counts ranged from two to 11 with an average of 5.4 pups per females. Thirteen of the 29 litters contained five pups each. Referring again to table 3, an average litter size. (L) of 5,4 would be expected when approximately 25 percent of tlie coyotes are killed each year. This is a substantially higher control rate than that indicated by the kill ratio (Kb) as determined above. Hovrcver, the litter size estimate (L) is biased toward that portion of the county where control is intensive, while the kill ratio (Kb) represents the entire county. This illustrates the difficulty of applying a simple model assuming a uniform control rate to field conditions wh&re the actual control rate varies locally. Nevertheless this comparison agrees with our concept of the "hot spot" pattern of control effectiveness and suggests that effects are most evident in the immediate areas of intensive control. We conclude that coyote control as practiced in Mendocino County has little impact on overall coyote numbers.
We have no recoTimendations to improva the effectiveness of predator control in Mendocino County for reducing livestock losses. Such recommenda- tions would depend on cost effectiveness data beyond the scape of this study.
If, as we believe, the existing program relieves predators from problem areas without significantly influencing overall coyote numbers, it may be con- sidered to serve the Interests of both ranchers and preservationists.
However, there is room for improvement in the collection of data from the animals taken in control,
As noted earlier, a number of statistics measurable from the control kill can serve as indices to the level of control being achieved. These include the proportion of yearlings in the breeding population (Cy/Cb in tables 1, 3), the proportion of females with litters (By, Ba), the litter size (L), the proportion of pups in the control kill (Kr), and the ratio be^een the conlrol kill and breeding population (Kb), With tlie. exception of the kill ratio (Kb) and litter size (L), as discussed above, little information of this kind exists in'Mendocino County.
This information could be determined if the age, reproductive status, and litter size were recorded for each coyote taken by control officers, 31 To determine the age would require one canine tooth from each coyote for laboratory counts of cementum layers (Linhart and Knowlton, 1967). This would not be necessary for animals which were obviously juvenile, Uterine examinations for reproduction data can readily be done in the field.
Regardless of the tima of year, the presence of placental scars will reveal that pups were born in the previous breeding season. The number of scars indicates the number of pups produced (Gier, 1968).
EFFECTS OF COYOTE CONTROL ON NOIWARGET SPECIES
Several of the sffective coyote killing fcechiiiques in present: use are not completely selectiva for coyotes. The catch of foxes, raccoons, skunlo, and otlier nontarget animals in coyote traps is grounds for much opposition to predator control (U.S. Congress, 1973; pages 320-342). m^ile we did not include these nontarget animals in our model, we wish to point out that the principles of population dynamics demonstrated for coyotes apply to other aniiual species as well. It is likely that most, if not all, popula- fcions of nonfcargat animals possess the ability to compensate for man-caused mortality by increased birth and reduced natural loss rates, just as coyotes do. Also the natural losses in the populations of these nontarget species should be similar to those of coyotes so that population turnover is high and the affects of removing a few additional animals inadvertently would be iiisignificant and difficult to even detect.
If this is true, predator control programs are not likely to eradicate or even seriously affect th& nontarget species. As a matter of record, governmental animal control programs have not significantly threatened the future of a single animal species, endangered or not (U.S. Congress, 1973; pages 380-382). None of this is to excuse the indiscriiiiinanl: destruction of wildlifa, but only to point out: that the incidental catch of nontarget animals in predator control programs is not, of itself, grounds for fcermi" nating predator control in areas of proven need.
CONCLUSION
This report discusses the lev&l of control needed far eradication of coyote populations and t-he feasibility of achieving such control. We emph.at— ically DO NOT recommend eradication as tha preferred coyota niariageiiient strategy. Eradicatioii is the limit of control intensity at the opposite end of the scale from no control. Both limits are important reference points to 32 to compare with intermediate levels of control. Our aim in this paper is to evaluate the effects of various management strategies and to elucidate their consequenc&s.
Killing coyotes unselectively \ri.th the techniques presently available, is not a very feasible means of reducing populations over broad geographical areas. This report suggests that other means should be found to reduce coyote depredations, and that better understanding of coyote population dynamics is required.
ACKNOWT.EDGEMENTS
We wish to thank t-I. Cummtngs and D. Wade> Cooperative Extension, and E, Garfcon, Division of EnvironDiental Studies, University of California, Davis, who contributed to th& validation phase of model development and provided valuable suggestions for the. improvement: of the manuscript. Also we wish to thank B, Weiss for clerical assistance and M. Vann, Director of Animal Control for Mendocino County for providing control data for the county.
33 LITERA.TURE CITED
Adams, C. C.
1930. Rational predatory animal control. Jour> Manunalogy 11(3) ; 353-358.
Anderson, F. M., G. E. Connolly, A. N. IIalter, and W. M. Longhurst. 1974, A computer simulation .study of deer in M&ndoclno County, California.
Oregon. Agric. Exp. Sta. T&ch. Bull. 130:72 pp.
Balser, D. S.
1964. Management of predator populations with antif&rtility agents.
Jour. Wildl. Manage. 28(2):352-358.
Cain, S. A., J. A. Kadlec, D. L. Alien, R. A. Cooley, M. G. Hornock&r, A. S. Leopolds and F. II. Wagner.
1972. Predator control -" 1971. Report to the Council on Enviroivnental .
Quality and the Departm&nb of the Interior by the Advisory Committee on Predator Control:207 pp.
Gier, H. T.
1968. Coyotes in Kansas, Kansas Agric. Exp. Sta. Bull. 393:118 pp.
IIenderson, F. R.
1972. Controlling coyote damaga. Kans. State Univ. Coop, Kv-t. Ssrv. Publ.
No. c-397:24 pp.
Knowlton> F. F-
1972. Preliminary interpretations of coyote population mechanics \dl.h some management implications. Jour. Wildl. Manage. 36(2):369-382.
Llnhart, S. B. and F. F. Knowlton.
1967. Determining age of coyotes by tooth cemenfcum layers. Jour. ffildl.
Manage. 31(2):362-365.
Linharfc, S. B., H. H. Brusman, and D, S. Balser.
1968. Field evaluation of an antifertiltty ag&nt, stilbestrol, for inliibiiting coyote, reproduction. Trans. N. Amer. Wildl. Conf. 33;316-326.
Swick, C. D.
1974. Operational management plan for th& coyota. Part I. Inventory.
Final Progress Report, Federal Aid in Wildlife Restoration, Project W~54~R-5 and 6. California Dept. of Fish and Gama, Sacramento, Ca. 30 pp.
34 U. S. Congress, House of Representatives.
1973, Jn: Predatory animals. Hearings before the Subcommittee on Fisheries and Wildlife Conservation and the Environment of the Committee on Merchant Marine and Fisheries. Mar. 19~20. Serial 93-2. Washington, D. C,: U. S. Govt. Printing Office, 397 pp.
Wade, D> A.
1973. Control of damage by coyotes and same other carnivores. Colo. Sts Univ. Coop. Ext. Serv, Bull, 482a:16 pp.
Young, S. P. and H. H, T. Jackson.
1951. The clever coyote. Stackpole Co., Harrisburg, Pa, All pp. 35 APPENDIX
PROGRAMMING AND CALCULATIONS
The r&lationships.shown in figure. 1 and table 1 of the main text of this paper were programmed for solution on a Wang Model 360 electronic calculator with Model CP-1 card programming attachment. In its final version the program contained 152 steps> The sequence of calculations was as follows:
1. Stora initial values for Cy> Ca, Cb, aad K (refer co fcabls 1 for explanation of syiubols). In each run the. initial values .for Cy, Ca, and Cb wer& 40, 60, and 100, respectively.
Insert program card 1.
Calculate and store D,.
2. 3.
4, Calculate By.
5. Apply By to Cy to det&rmine the number of yearling females with litters.
6. Calculate Ba.
7. Apply Ba to Ca to d&termine the number of adult females with litters.
8. Sura numbers of yearling and adult females with litters to datermine Pl i,
8a. In runs where part of th& breeding females are subjacted to cliemosterllization, apply S to Pl to determina the. value of Fl after birth suppression.
9. Calculate L.
10. Calculate P.
11. Calculate Cm.
12. Remove program card 1; insert card 2.
13. Calculate Pk and subtract: it from P.
Calculate Ak and subtract it from Cb.
Calculate and store D^.
14. 15.
16. Calculate Np.
17. Apply Np to (P - Pk.) to determine Pn.
18. Subtract Pn from (P •- Pk) to d&termine Cy for the next year.
19.. Calculate Na.
20, Apply Na to CCb - Ak) to der-ermine An.
21. Subtract An from CCb - Ak) to d&fc&rmtoe Ca for tIie next year, 36 22. Add Cy and Ca (from steps 18 and 21) bo determine Cb for the next year.
23. Remove program card 2.
Steps 2-23 constitute one annual cycla in the coyote modal. To begin the next year the user returns to step 2, As calculated in steps 18, 21, and 22, the initial values for Cy, Ca, and Cb for the next year are in storage. TI.TO program cards were required to accommodate the entire model, Card 1 cov&red reproduction and card 2 the mortality phase of the model.
Throughout this model the calculations were sequential and endogenous, i,e., each step proceeded from values calculat&d and stored previously, The only exceptions to this were as follows:
A. To begin a run four initial values were stored (st&p 1).
B. STOP commands wer& used throughout th.e program to permit monitoring the calculations. t'7henever D, < 0.5 the calculated values of By, Ba, and L (steps 4, 6, and 9} Exceeded the specified maxima (figs. 2 and 3). In such cases each excessive value was replaced by the specified maximum b&fore tlie calcula- tions were continu&d.
C. Step 8a was used only in runs whera part of the females were prevented from breeding. This step was p&rformed manually because the limited storage capacity of the Wang 360 prevented storing the value of S.
The Wang 360 calculator used in this study features visual display of results. No output Is printed. In using this model it was necessary to copy the output as displayed (see table 2, for example). In practice it was found that the calculations were made as fast as the operator could change cards and copy the results. This procedure was slower than it would have been on a high. speed computer, but was much more efficient in the formulation, validation, and programming stages,
The output from this model (table 2) does not include all th.& variables sho\ffi in tabla 1. However, the. variables not explicit in the mod&l can readily be calculated from the output. In early stages of model dev&lopnient all Lhe variables in table 1 were- included as output but it soon became apparent that it would be more. efficient to limit the program to essentials, calculating the other variables from the output after the model reached stability.
37 /
Stevenson, Garrett
Subject:FW: Coyote meeting 7/17/23
From: Aidee Calderon < >
Sent: Monday, July 17, 2023 4:04 PM
To: PublicComment-AutoResponse <[email protected]> Subject: Coyote meeting 7/17/23
a
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To whom it may concern,
I hope this email finds everyone well, and I write to you today in solidarity of the wildlife we coexist with. I write in solidarity of not only the coyotes who are being threatened by the human populations and whatever actions we may decide to take or not take today but the other wildlife that could very well be affected by the removal of these animals.
For 27years I have lived in Pasadena with my family, only a few minutes from Eaton canyon, we have seen coyotes come down the mountains, team to cross the street by observing traffic patterns, I have walked my dogs in their presence, I have also had community cats thrive and live to old age in their presence.
Never have I once feared to be among such a remarkably intelligent creature, while I have always respected their space and their capabilities, I have also understood that small and potential prey looking animals should not "live" outside, be left unsupervised outside, and my biggest fear for my community cats were never coyotes, but rather humans and high speed vehicles.
To have my animals live outside, to live in a city so close to the mountains and also call it my home comes with the understanding that this is their home and they are sharing it with us, and no one ever asked wildlife if we could move in and build over their homes.
My heart will always feel for the owners that have lost their pets to wildlife, but I insist again that if I have my animal be outdoors, and be housed outside, this HAS to come with the understanding of what wildlife will do, and we cannot be upset about this, about them acting as such... wildlife.
Coming from a background in Biology, Animal science and Veterinary medicine, I am confident and know I can find the necessary articles to back up the following statements: If you remove an animal from their home and try to relocate them elsewhere, they will fail, they will not survive. It takes many years for an animal to be able to adapt to new environments. For example, taking a feline from one neighborhood and placing them in another, I can almost 100% guarantee that the animal will not thrive because they do not know this environment, they do not know how to navigate it and how to survive in it.
The additional problem with removing a skilled predator such as a coyote is that there will be a gap in our ecosystem.
Gaps are meant to be filled, and it will be filled, by another species. It is inevitable that when you remove one species, another will come and take their place.
As the top carnivore in some ecosystems, coyotes provide a number of benefits including regulating the populations of smaller predator species, such as skunks, raccoons, and foxes, which helps boost biodiversity.
Imagine that Coyotes had a drastic drop in their population or were driven to non existence, you would have a surge in skunks and raccoons which are also popular city dwellers. The appropriate response is that you will eventually bring in predators that also have skunks and raccoons in their diets. The latter will be that in a surge of population of 7/17/2023
Item 9
raccoons and skunks (without Coyotes being here to regulate these populations), these common city dwelling animals will exhaust whatever food source they rely on to sustain themselves because of their growing numbers.
As someone who has grown up in this beautiful city with the mountains in such ease of access, I have grown up with a deep love and appreciation watching these animals be forced to learn to survive in our city. It pains me very much that today this is a topic of interest, that my city would even consider such a cold and heinous idea. I do not think it is our place to remove something that has been here for such a long time. I do think we owe it to our pets, who many of us would walk endless miles for, to learn to coexist safely with this long residing predator, the way our mountain residents are doing now with bears, snakes, and many others.
We owe it to ourselves, to our pets, and our neighbors the Coyotes.
Thank you for your time,
Aidee Calderon Estrada
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