The Effectiveness Of Trap-Neuter-Release

A couple weeks ago I wrote about the factors that influence some people not to spay or neuter companion animals. While this is a problem for these animals with guardians, an even larger challenge faced by spay/neuter advocates is the free-roaming animal population. Ally Cat Allies estimates that, while 82% of household cats are spayed or neutered, only 2.3% of stray and feral cats are sterilized. In this post I will explore some of the research that addresses the free-roaming animal population, focusing specifically on efforts to reduce the feral cat population.

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Part of the shelter overpopulation problem is due to the relinquishment of unwanted companion animals. In the United Kingdom, 60% of cats in shelters had been relinquished by their human companions. In Spain in 2008, more than 118,000 dogs and 38,700 cats were recovered from the streets. Only 14% of these dogs had been lost, while the remainder had been abandoned. Of the cats recovered, only 5% had been lost, while the remainder had been abandoned. Add to this the feral and free-roaming population and the problem can seem overwhelming.

Trap-Neuter-Release (TNR) programs are a popular means of addressing the feral cat population. Two researchers, Anderson and Martin, used information about the stray cat population in one community to develop matrix population models to predict whether trap-euthanasia programs or TNR programs would be better at controlling feral cat populations. They found that, when comparing annual euthanasia of over 50% of the feral cat population to the annual neutering of over 50% of the population, their model found shelter-euthanasia to be more successful at controlling the population of free-roaming cats.

However, animal protectionists will be happy to know that there is also evidence that TNR programs are successful. Earlier this year, Boks surveyed successful TNR programs and found that these programs can have a significant impact. Some of these successes include: Orange County, Florida where, euthanasia decreased by 18% and cost savings totaled more than $100,000 in 6 years of implementing TNR, and the Upper West Side in New York City, which experienced a 73% drop in stray cat intakes within 3 years.

TNR programs are most effective when they are accompanied by education and outreach efforts. A study at the University of Rome tracked the country’s TNR programs for the decade after they were implemented and found that, although they did reduce the feral cat population, their effects were influenced by new cats who immigrated into the population, often due to owner abandonment. As such, the study suggests: “[TNR] efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy.”

As with so many problems facing animals, the solution is necessarily multi-faceted. To successfully address companion animal overpopulation and reduce shelter deaths what is needed is a combination of programs, implemented by veterinarians, shelters, rescue groups, spay/neuter organizations, and other animal advocacy groups working together to address the issues in their communities.