Shelter Pet Population 101

Valerie Hayes

Another post from the archive.  This was originally published on in 2010.  Learn more at the Atlanta screening of Redemption tomorrow, which will be followed by a presentation on how to implement the No Kill Equation in your community.  Tickets are only $5 and are available here.


Bella, rescued from the high-kill Carroll County Animal Shelter in Georgia.

The science of population dynamics teaches us that there are really only four factors that influence the size of a population of animals or plants. They are birth rate,death rate,immigration and emigration.

The birth rate is simply the number of animals born in that population in a given time period. The death rate is the number dying in that same time period. Immigration is the rate at which animals join the population in question from some other population. Emigration is the rate at which animals leave the population in question for some other population.

The maximum sustainable size of a given population is governed by the habitat’s carrying capacity. The carrying capacity is determined by limiting factors—resources such as food, water and shelter.

Population biologists refer to groups of interacting populations of a given species as a metapopulation, basically a ‘population of populations’. They interact by exchanging members through immigration and emigration. Each of these interacting populations within a metapopulation is called a subpopulation.

Why the science lesson in a column about animal welfare? Simple—looking at the pets in a given community as a metapopulation can help us see how to save all the healthy and treatable pets in that community. A community’s pets can be divided into three subpopulations. There are pets with homes and pets without homes. These twosubpopulations interact and exchange members. Pets with homes can join the ranks of the homeless when they are lost or abandoned. Pets without homes can get homes when they are found, rescued or adopted. This exchange process often involves an animal entering the third subpopulation of pets in a community—those in its shelters and rescue groups.

Entering this third subpopulation has traditionally proved deadly for animals because shelters have long relied on the death rate as a means of controlling the size of this subpopulation. While there has been much talk about spaying and neutering*, which curbs the birth rate, it is only fairly recently that some shelters have begun spaying and neutering all adopted pets. Many still adopt out unaltered animals, sometimes relying on contracts or monetary deposits to induce adopters to have the pet altered by their own veterinarian after adoption. This is an unwieldy system guaranteed to have some level of non-compliance, resulting in the system’s failure. The traditional model of animal sheltering has failed miserably because it simply does not address the four factors which influence the shelter pet population in a comprehensive or meaningful way.

“Wait a minute, there is a pet overpopulation problem!”, you say. “There are more pets entering shelters than there are homes for them. The number of pets exceeds the carrying capacity for pets. There simply aren’t enough homes for them all. The number of homes is the limiting factor.”

“Not so!”, says Nathan Winograd, author of Redemption: the Myth of Pet Overpopulation and the No Kill Revolution in America. “Not so!” says Maddie’s Fund,  the actual data indicate otherwise. There are 17 million people in this country who are looking to acquire a dog or cat this year, but haven’t yet decided from where—the ‘swing voters’ . About 8 million animals will enter shelters, and of those, about 4 million will be killed. Of those 4 million killed, about 90% are healthy or savable. Therefore, there are 17 million potential homes for fewer than 4 million animals. Homes are not a limiting factor. Pet overpopulation, far from being received wisdom, is in fact, a myth, and a deadly one. It has too long served as a smokescreen for the real reason why the death rate is used to control the shelter pet population—the habit of institutionalized uncaring in the shelters themselves.

Enter the No Kill Equation, the first and only proven method for saving all healthy and treatable animals in a community’s shelter pet population. It succeeds by comprehensively addressing the shelter pet population using the three non-lethal factors which influence any population. With the NKE, shelters are restored to the original and proper definition of the term—places of safety for animals. Euthanasia too is restored to the original and proper definition of the term, and is used only for those animals who truly are irremediably suffering or vicious. The NKE has 11 points. Let’s have a look at each one.

Tabby Cat

Trap-Neuter-Return for feral cats is an integral part of the No Kill Equation.

1. Feral cat TNR Program: Also known as ‘Trap, Neuter, Return’, TNR keeps feral cats out of the shelter pet population. Feral cats, called ‘community cats’ by some, have homes. They live outside, on their own and don’t belong in shelters. They grew up without being socialized to humans and can’t be adopted into human families. Volunteer caretakers feed and monitor feral cat colonies. They humanely trap the cats and have them spayed and neutered, then return them to their habitats and continue caring for them there. This controls the birth rate. When new cats immigrate into the community’s population, they can be TNRed as well, or adopted into homes if not really feral. The immigration rate is lower than with the traditional ‘catch and kill’ method of dealing with feral cats, however, because with TNR, the niche occupied by cats is not left vacant—cats are territorial. The ‘catch and kill’ method perpetuates a never-ending cycle of killing. It is also more costly than TNR, which relies largely on the volunteer labor of caring community members. Over time, managed colonies shrink as the cats live out their life spans.

2. High Volume, Low Cost Spay/Neuter: By making spay-neuter readily available to the pets of all members of the community, the birth rate in the overall pet population is effectively curbed, reducing the number of animals entering the shelter population (immigration). Studies, including the recent Petsmart study, indicate that a major obstacle to spay-neuter is the cost of the surgery. Low cost clinics reduce the number of animals entering shelters. Punitive laws, such as mandatory spay-neuter, or MSN, actually increase the number of pets entering shelters.

3. Rescue Groups: By working with rescue groups, a shelter reduces its population through emigration—the animals leave the shelter to go into rescue and ultimately into homes. The number of animals between homes is not limited by the four walls of the shelter building. Members of the community pitch in. Lives are saved. Remember the responsible public–that previously ignored stakeholder?

4. Foster Care: Once again, by relying on the responsible public, this time with a comprehensive foster care program in which all orphaned kittens and puppies, sick or injured animals and those in need of behavioral rehabilitation have a place to go until they are ready to be adopted, animals are saved. The four walls of the shelter, previously identified as a limiting factor, no longer are so. The shelter is more a part of the community. Volunteers work for free and create good will.

5. A Comprehensive Adoption Program: Most people who acquire pets don’t get them from shelters. Getting animals adopted into homes, having them emigrate into the population of pets with homes needs to be a central mission of any shelter. Shelters need to present a clean and inviting environment to the public and to effectively market shelter pets in a variety of different ways, including the internet and social media. Shelters should be open at times when working people and families with children can actually visit them. They should bring the pets into the community with offsite adoptions. Volunteers can help with this. It needs to be done vigorously.

George was rescued from the high-kill Carroll County Animal Shelter.

George was rescued from the high-kill Carroll County Animal Shelter.

6. Pet Retention: Sometimes, a little problem-solving can prevent the immigration of pets from the homed population into the shelter population. Blaming people is counterproductive, but helping them solve the problems that lead to pets being surrendered to shelters gets results. Do they need some pet food to get through a difficult financial time? Tips on getting their cat to use the litter box? A referral for training for a rambunctious dog? Shelters need to act like they believe that pets are not disposable and to help people do the right thing wherever possible.

7. Medical and Behavioral Programs: Shelters are obligated to ensure that all animals in their care who are ready for adoption stay that way, and that those who are sick, injured, too young or in need of behavioral rehabilitation get it. A healthy shelter pet population will emigrate into the homed pet population. Failure to have these programs results in an increased and unnecessary death rate.

8. Public Relations/Community Involvement: By keeping the shelter and its programs in the public eye, there are more opportunities for shelter pets to emigrate into the homed pet population by being adopted, more opportunities to reduce the birth rate through low-cost spay-neuter, more opportunities to help people retain pets, thus reducing the immigration rate, and more volunteers recruited and donations obtained for programs that reduce limiting factors and reduce the death rate.

9. Volunteers: Shelter pets can’t live without them. They work at spay-neuter clinics, reducing the birth rate. They bottle feed orphaned puppies and kittens, and care for the sick and injured, reducing the death rate. They provide foster homes for animals, removing the space within a shelter’s four walls as a limiting factor. They take pets to offsite adoptions, increasing the emigration rate. They offer advice and assistance, preventing some animals from ending up at the shelter in the first place, reducing the immigration rate. They create good will and make the shelter a part of the community it serves. Shelters need to treat them like the powerful positive force that they are.

10. Proactive Redemptions: Many pets at shelters are lost. They have homes and should be returned to them. Traditionally the rate of lost pets being returned to their homes by shelters has been very low and many are killed, resulting in a high death rateBeing proactive prevents this unnecessary immigration or at least greatly reduces its duration, freeing up resources for animals who really don’t have homes.

11. A Compassionate Director: The director is the one with both the power and the responsibility to make it all happen, the keystone that holds the whole NKE together. Sadly such directors are not easy to come by, and many shelter directors thwart rather than promote the implementation of the NKE. The bottom line is that the shelter director must reduce the shelter pet death rate so that it includes only those animals who are irremediably sick, injured or truly vicious. That means that 90% or more of the animals entering the shelter pet population leave that population alive. The director makes the shelter into a true safety net for animals. Such a shelter has a positive image and is both an asset to its community and a point of pride. The circle of compassion is extended to those animals without homes, and they can be more efficiently moved into the homed animal population through the shelter. A growing list of communities as diverse as Tompkins County, NY, Reno, NV, Charlottesville, VA and Shelby County, KY has already accomplished this, even as their shelters maintain an open-door policy, accepting any pet in need.

*In 1974 a group of large national organizations which considered themselves the ‘stakeholders’ in the issue of animal sheltering met and devised the strategy for dealing with shelter pets that is still with us today. It is called ‘Legislate, Educate, Sterilize’ and is abbreviated LES. The legislation is generally punitive towards the pet owning public and to the pets themselves—license animals or they can be seized and killed, vaccinate the animals or they may be seized and killed, spay or neuter the animals or they may be seized and killed. The education generally involves taking impounded pets into schools and telling the children that it is bad to be cruel to animals and bad not to spay and neuter. Never mind that these impounded pets may be subsequently killed by the shelter. This ‘education’ is expected to reduce the numbers of animals entering shelters at some future time, though the mechanism and effectiveness remain undocumented after more than 30 years. Sterilization refers to spay-neuter, but the self-appointed stakeholders specifically opposed the low-cost clinics which make spay-neuter readily available to the community. Shelters did not have to spay or neuter animals they adopted out. What then did LES really mean? Unfortunately it has meant ‘blame the public’, or rather, the ‘irresponsible public’. Who is the ‘irresponsible public’? It is usually identified as ‘people who don’t spay and neuter’. Never mind that the cost of the surgery is often the reason for not doing it, and most people would have it done if it were affordable or free. The ‘stakeholders’ had come out in opposition to free and low-cost spay-neuter clinics, despite the fact that an organization called Mercy Crusade had established a very successful program in Los Angeles in 1971. What about the ‘responsible public’? Are we not ‘stakeholders’? The stakeholder that wasn’t at the table back in 1974 has begun asserting itself and demanding reform of this broken system in the form of the No Kill Equation. The responsible public is up against the entrenched bureaucracy of the large national groups and the entrenched attitudes which they have promulgated all these years.

This article originally appeared here.

2 Responses to “Shelter Pet Population 101”

  • Tina Clark Says:

    Great article! I have tried to explain to people why “shelter overpopulation” does not equate to “pet overpopulation” but didn’t have such a clear scientific way to describe it. People confuse the subpopulation of the pound with the metapopulation at large. And your use of these principles to describe how the No Kill Equation works to end the “shelter overpopulation” is perfect.

  • Valerie Hayes Says:

    Thanks, Tina! I’m glad you found it helpful. One of my goals was to show how and why the No Kill Equation is so much more comprehensive and therefore effective than the traditional reliance on spay-neuter to solve this problem. Spay-neuter, while very, very important, cannot solve the problem by itself, because it does not address all facets of the problem.

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