Short answer: yes, and there’s an 11-year study to prove it.

A 2003 study in the Journal of the American Veterinary Medical Association, led by veterinarian Julie Levy, tracked the free-roaming cat colonies on a university campus for eleven years under a Trap-Neuter-Return program. The population fell 66%, from 68 cats down to 23. No kittens at all were observed on site after 1995. That’s not a projection or a model. It’s eleven years of real colonies, actually counted, actually tracked.

If you run a TNR program and you’ve ever been asked “does this even work, or are you just feeding a problem,” that number is your answer. Here’s the rest of the story, and why it matters for how you run your own colonies.

The study, in plain terms

TNR programs trap feral and community cats, spay or neuter them, and return them to their territory instead of removing them. The theory has always been straightforward: a stable, non-reproducing colony holds its territory against new cats moving in, and the population declines naturally as older cats age out with no kittens replacing them. Levy’s long-running campus study is one of the clearest real-world confirmations of that theory in action. Not a lab model: a real set of colonies, followed year over year, long enough to see the whole curve: intervention, stabilization, and decline.

Eleven years is the part that matters most. A lot of TNR skepticism comes from looking at year one or two, when a colony’s population hasn’t visibly changed yet, and concluding the program “isn’t working.” This study is the answer to that specific doubt. TNR is not a quick fix. It’s a slow, compounding one, and the data backs exactly that shape.

And here is the part worth knowing before someone else tells you: the same study reports that stray and abandoned cats kept arriving on site throughout. Sterilizing the resident cats stopped the colonies producing kittens; it did not stop people dumping cats nearby. Anyone who argues TNR “doesn’t work because the numbers never go to zero” is pointing at that, and they are pointing at something real. The honest version of the claim is the stronger one: TNR reliably stops a colony breeding, and the remaining pressure on your numbers is abandonment, which is a different problem with a different fix. Knowing which of the two you are actually looking at, in your own colony, is the whole game.

Why the neighbor, not the public, is the actual audience for this number

Polling on this is limited, and the best-known surveys were commissioned by an advocacy group, so treat the numbers with that in mind. Still, two national surveys by Best Friends Animal Society found about two-thirds of Americans (68% in 2014, 72% in 2017) preferring TNR to rounding cats up and euthanizing them. In the abstract, most people are already on board. The real friction usually isn’t “the public.” It’s the specific neighbor who has a colony near their property and called someone about it. That’s a much smaller, much more specific audience than “everyone who might see a Facebook post,” and it means the messaging that actually moves the needle looks different from generic awareness content. It’s not “TNR is humane” (most people already agree). It’s “here’s the actual number for the actual colony near you, and here’s what the trend looks like over time.”

Where Purralytics fits

This is exactly the kind of data a TNR program needs to be able to produce for its own colonies, not just cite from someone else’s eleven-year study. If a neighbor calls about the colony behind the shopping plaza, the strongest answer isn’t a citation to somebody else’s paper. It’s your own numbers for that colony: when it was first tracked, how many cats, how many kittens born each season since, and whether that count is actually declining the way the research says it should. Purralytics exists to make that answer producible in under a minute instead of requiring someone to reconstruct it from memory or a shoebox of index cards.

If your program doesn’t track colony population trends over time yet, that’s the single most useful thing to start doing this season. Not for a paper, but for the next time someone asks whether any of this is actually working.

Source

Levy JK, Gale DW, Gale LA. “Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population.” Journal of the American Veterinary Medical Association, 2003; 222(1):42-46. Eleven-year campus study; population declined 66% (68 cats to 23) between the 1996 census and 2002; no kittens observed on site after 1995; stray and abandoned cats continued to arrive during the study period. Public support figures: Best Friends Animal Society national surveys, 2014 (68% preferred TNR; 24% impoundment and euthanasia) and 2017 (72% and 18%); commissioned by an advocacy organization, and not every survey on this question has found support this high. A 2019 follow-up of the same campus population was published in Animals (“Back to School: An Updated Evaluation of the Effectiveness of a Long-Term Trap-Neuter-Return Program on a University’s Free-Roaming Cat Population”).

Purralytics is colony-management software built by a working TNR rescue, for TNR rescues. The free tier covers colony records, cat profiles, and caretaker check-ins.