Population Dynamics of Free-roaming cats: managing outdoor cat colonies to meet your goals
An ACC&D Flagship Initiative
"How many free-roaming cats do we need to reach to stabilize, reduce or eventually eliminate a specific population?"
TNR programs certainly make a difference for the cats that they reach. However, the question above is one that many involved in Trap-Neuter-Return (TNR) programs are asking as they set and strive to achieve goals to impact the population of cats at the colony or community level.
"What difference can a multi-year contraceptive make?"
This question is a critical one for ACC&D. We are striving to understand if a promising contraceptive for cats, used in the field and very affordable, could be a useful tool for TNR programs. We discovered that there is a lot that’s not understood about how to achieve the greatest impact with surgery-based TNR. We assume that permanent sterilization (surgical or non), removal of animals, and multi-year contraceptives will have different impacts. We know that free-roaming cats have, on average, much shorter lifespans than pets – so just how long must fertility control last to benefit a colony of cats?
We learned that the wildlife field has more sophisticated software than has been used before to understand cat populations. So we convened a team (see below) that includes experts in wildlife conservation, free-roaming cat welfare, feline behavior, and TNR.
ACC&D’s Free-Roaming Cat Population Dynamics Flagship Initiative
In 2013 and 2014 we worked to combine field research data with sophisticated computer modeling software to develop the most comprehensive feline population model available to date. In November 2014, “Simulating Free-Roaming Cat Population Management Options in Open Demographic Environments,” was published in the peer-reviewed, open-access journal PLOS ONE. The study estimates the percentage of cats that must be reached by different methods to achieve different goals. (Our press release summarizes results.)
Our Guidance Document translates model findings into guidelines for cat management programs. And because it is hard to evaluate impact without knowing how many cats you are starting with or measuring change over time, we’ve also created "how-to" guide to “counting cats” and monitoring cat population numbers to evaluate intervention impact.
And we’re just getting started! We are currently working on a second phase of modeling that will look at combination approaches to free-roaming cat population management (e.g., removing social kittens for adoption or combining surgical sterilization with long-term contraception) and fold in the economic costs of different strategies.
We’ll also be looking for your participation to help improve the model! If you have a well-run TNR program and are hungry for ways to better measure and evaluate your impact, please read the materials above and then contact us about getting involved.
The ACC&D Free-Roaming Cat Model Development Team:
- Aaron Anderson, PhD * National Wildlife Research Center, USDA APHIS
- John Boone, PhD * Great Basin Bird Observatory
- Joyce Briggs, MS * Alliance for Contraception in Cats & Dogs
- Dennis Lawler, DVM, FNAP * Illinois State Museum, Pacific Marine Mammal Center Laguna Beach
- Julie Levy, DVM, PhD, DACVIM * University of Florida College of Veterinary Medicine
- Philip Miller, PhD * IUCN/SSC Conservation Breeding Specialist Group
- Felicia Nutter, DVM, PhD, DACZM * Tufts University
- Margaret Slater, DVM, PhD * ASPCA
- Chris Slootmaker, PhD candidate * National Wildlife Research Center, USDA APHIS
- Steve Zawistowski, PhD, CAAB * ASPCA
Our thanks to the ASPCA for funding the population modeling phase of this Flagship Initiative.