Catch and Kill vs TNR: A Look at Sustainability

By: | October 16, 2019

One of the major opponents to TNR are bird people. They often cite a study, conducted by scientists Clark and Castillo for the Department of Environmental Studies – Florida International University, which found that after 2 years there was no change in the feral cat population – and that these cat colonies had even increased, somewhat. This is not particularly revolutionary data – TNR never purported to change the feral cat landscape in just two years. Instead, in a 17-year-long study conducted by Daniel D. Spehar and Peter J. Wolf, we see something much more interesting: after nearly two decades of TNR, all the cats are gone. Further, they write, “Up to one-third of the cats trapped were sociable and adopted into homes; the remainder were sterilized and vaccinated before being returned to the waterfront, where they declined in number over time due to attrition.”

But let’s let Clark and Castillo continue. In their zeal for catch and kill, bird enthusiasts only read the headline of the study. But the scientists write more:

“Our results emphasize the role that human interference and negligence play in the population dynamics of managed cat colonies. lllegal dumping of unwanted cats and the attraction of stray cats to the provisioned food counter-balanced reductions in cat numbers caused by death or adoption.”

Over the course of two years, this is a reasonable conclusion. Their inclusion of “adoption” here is also interesting: the 45 cats born per year for every human is not a problem we can adopt our way out of. Shelters who trap feral cats, warehouse them endlessly in a misguided attempt to socialize them, and then find themselves too full to help actual friendly kittens could heed Clark and Castillo’s words. With nowhere to go, friendly cats get dumped.

Clark and Castillo, in their conclusion, continue:

“Our small sample size (two cat colonies) and short time duration of observation (1 year) may limit the strength of our results.”

Hmm. Another major difference: the study over the course of decade’s deals with hundreds of cats – the Clark and Castillo study has less than 50.

In another study, Wildlife Research scientists write about catch and kill vs TNR:

“After 1 year, populations treated with euthanasia generally decreased whereas populations treated with TNR either remained unchanged or decreased slightly […] Euthanasia resulted in greater total population decreases than did TNR and a combination of euthanasia and TNR; however, the total effort required to reduce each population by 1% was highest for euthanasia.”

Again: over the course of 1 year. According to this study, TNR was most effective when 75% or greater of the cats were sterilized. (Or trap and kill most effective when 75% of the cats were euthanized).

Here’s what we know to be true, based on our observations here in St Louis:

  • Catch and kill will reduce the number of cats temporarily – that’s common sense. But just as the Wildlife Research scientists assert, it’s hugely resource intensive. No one is going to raise their hands and offer to help trap and kill for free. That makes euthanasia expensive and therefore unsustainable – especially when we remember the bird study’s assertion that illegal dumping of cats and cats wandering into the area is a problem that will continue. Thus, necessitating more catching and killing on and on and on forever and ever.
  • TNR brings human beings together. Over 1700 cats were TNRed last year by St Louis Feral Cat Outreach alone. The humans involved in this effort included the 80 or so volunteers, plus all the colony caretakers of 1700 cats, plus many concerned citizens doing one-off TNR. These are all people who worked for free. Given the state of flux at our animal controls, it seems unlikely that something as resource intensive as paying trappers to trap and kill is the answer to the feral cat problem.Wildlife Research continues:

“Therefore, both euthanasia and TNR would require immigration to be concomitantly controlled or reduced under both scenarios.”

Translation: Catch and kill doesn’t work if people are not fixing their cats. Catch and kill doesn’t work if people are illegally dumping animals. Why is this relevant? Because it speaks to the most important reason why TNR is sustainable but catch and kill isn’t: TNR forces human beings to be pro-active in the reduction of community cat populations. It forces shelters to contend with litters of kittens. It gives adoptable community cats a chance at indoor life.

Something catch and kill proponents forget: TNR empowers colony caretakers, who love their cats, to do something about explosive population. Instead of hiding in the shadows, caretakers are now choosing to join with animal welfare groups and fix their cats. When it comes to beloved community cats who these folks will do anything to protect, the choice is do nothing or do TNR.

That’s what sustainability looks like.

The community cat problem will not be solved by a handful of Animal Control Officers directed to trap and kill.

So you wanna help the birds?

Here’s how to help the birds:

  • Support local shelters when they stay open admission. Birds are most at risk because of illegal dumping of animals – so with the troubling increase in managed intake or limited admission no kill shelters in the region, that’s what’s going to increase cat populations. This is what contributes to illegal dumping, a problem that’s pointed to in every major TNR study.
  • Support spay and neuter efforts – pet cats who are allowed to roam outside must be sterilized.
  • Work to protect bird habitats decimated by humans. Although we’ve only touched on the cats and their destruction of bird species, it’s also true that the most massive impact on all species in North America is from humans destroying habitat. Be mindful of your consumption.

So. It’s true that catch and kill decreases cat population, at least in the short term. But it’s a tactic that is grossly expensive, extremely cruel, and unsustainable.  If you want an army of volunteers and colony caretakers making a difference, right now, for relatively cheap – you’ll need to look to TNR.

Read the studies:

https://abcbirds.org/wp-content/uploads/2015/05/Castillo-and-Clarke-2003-TNR-ineffective-in-controlling-cat-colonies1.pdf

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5704110/

https://pdfs.semanticscholar.org/ab8a/31b2c6459dba0ded3f7ef545b916a62080cb.pdf