Best Friends Blog

How the war on cats is spurred on by deliberate misinformation

Humane-live-traps-community-feral-cats-TNR-2065If you follow any of the seemingly never-ending back and forth between advocates who promote trap-neuter-return (TNR) as the only humane solution to reduce the number of free-roaming cats and those who, well, don’t have a solution other than to say that cats are one of the greatest problems facing humanity, then you probably caught the news of the release of a new book on the topic. Cat Wars: The Devastating Consequences of a Cuddly Killer, published by Princeton University Press on September 13, makes a plethora of ridiculous claims about cats, but what shocked me, and many others, was the suggestion that cats should be removed “by any means necessary.” Such a statement is a dangerous dog whistle to anyone who has bought into the idea that cats are evil, and that they should do whatever it takes to “get rid” of cats, whether that’s using poison, rifles or anything else.

Shortly after its release of the book, Princeton University Press posted a document online outlining “summary points” from Cat Wars authors Peter Marra and Chris Santella. In it, the authors attempt to soften their call for killing while reiterating their rationale for it. And, like so many claims in the book itself, their summary points fail to stand up to even modest scrutiny.

With the help of the Best Friends Cat Advocacy Team, a group of dedicated attorneys and analysts who know this issue and the science behind it, we have put together this piece that fact-checks the claims made by the publishers and authors of this book. The claims come from them; we present you with the facts.


Gregory Castle
CEO Best Friends Animal Society



Claim:     The authors in no way condone or support the inhumane treatment of any animal. Peter Marra has devoted his life to the study and protection of all animals, including cats.

Facts:     Promoting the killing of this country’s most popular pet on an unprecedented scale can hardly be considered humane. The fact that Princeton University Press, publisher of Cat Wars, felt compelled to issue such a response is quite telling: The book’s message is clear enough to readers, but it’s also unacceptable.

Claim:     There’s an estimated 90 million owned cats and 60 to 100 million free-ranging, unowned cats in the U.S. The number of outdoor cats in the U.S. has never been higher.

Facts:     There are no credible estimates for the number of unowned cats in the U.S., nor is there any evidence to suggest that the number of outdoor cats is at an all-time high. On the contrary, there’s ample evidence to suggest that this number is likely decreasing. Sterilization rates among pet cats today, for example, have been steadily increasing in recent years and appear to be at an all-time high of about 91 percent, [1] a point the authors concede.

In addition, more cats live indoors-only than ever before. According to one national survey, 64 percent of pet cats are kept indoors during the day and 76 percent at night, significant increases over the rates even 10 years earlier (57 percent and 68 percent, respectively). [1] And a survey of metropolitan Chicago cat owners found that 87.2 percent of respondents’ cats “never went outdoors.” [2] Moreover, about half of the cats who do have access to the outdoors are outside for no more than 2–4 hours each day. [3-5]

stray-cats-duoClaim:     It is clearly inhumane to let cats roam freely. Outdoor cats get hit by cars, preyed upon by other animals, and can contract — and spread — a variety of diseases. Data on unowned outdoor cats suggest that 50 to 75 percent of kittens born outdoors do not survive to adulthood. If kittens do reach adulthood, their life expectancy is just two years without caregivers providing regular food and water. Even with this intervention, life expectancy is around six years, less than half that of indoor cats.

Facts:     Even if the authors’ concerns are genuine, they offer no data to support their claims. Their suggestion that the risks to cats and kittens are so great and their life expectancy so short directly contradicts the authors’ previous suggestion that these cats are reproducing at an alarming rate. They can’t have it both ways.

Moreover, data from large-scale sterilization programs demonstrate that community cats are quite healthy. Of the 2,366 cats admitted to a two-year, high-impact return-to-field program in one Alachua County, Florida, zip code for example, only 16 (0.7 percent) were ineligible for the program due to health issues. [6] In San José, California, where more than 10,000 community cats were sterilized and returned over a four-year period as part of a shelter-based community cat program, it was observed that “impounded feral cats are surprisingly healthy and have good bodyweight.” [7] This same program saw a 20 percent decrease in “dead cat pick-up off the streets” following the implementation of shelter-based TNR.

Claim:     The impacts of cat predation on bird and other wildlife populations, on both islands and mainland, are well documented. Cats have caused a minimum of 33 global extinctions, and a significant number of declines of at least another 142 species of reptiles, birds and mammals. A study published in 2013, in the peer-reviewed journal Nature Communications (with Marra as senior author), confirmed that cats kill an estimated 1.3 to 4.0 (with a median of 2.4) billion birds per year, with the majority of the mortality (69 percent) caused by unowned cats. Mammal mortality is equally alarming, with 6.3 to 22.3 (with a median of 12.3) billion mammals killed every year by outdoor cats. Mortality for amphibians and reptiles is in the hundreds of millions — at 95 to 299 million amphibians, and 258 to 822 million reptiles per year, respectively.

Facts:     It’s well known that the 33 global extinctions referred to here occurred on small oceanic islands; to suggest otherwise is highly misleading. In addition, more than 75 percent of islands with cats have various other introduced predators (e.g., rats, mongoose, stoats, weasels, dogs, pigs), making it difficult to attribute impacts to any one species. [8] Moreover, researchers reviewing more than 80 predation studies have concluded that “there are few, if any studies apart from island ones that actually demonstrate that cats have reduced bird populations.” [9]

Again, the authors provide no evidence to the contrary. As the Royal Society for the Protection of Birds explains: “It is likely that most of the birds killed by cats would have died anyway from other causes before the next breeding season, so cats are unlikely to have a major impact on populations.” [10] Indeed, the organization’s former director of conservation responded to Cat Wars directly: “If you look at all the conservation issues in the country, [predation by cats] comes quite low down the list.… Once you have sorted out climate change, agriculture, overfishing, water pollution, over-abstraction, and illegal killing of birds of prey, then maybe we will come on to the cats.” [11]

Regarding their mortality estimates, it’s important to understand that the assumptions Marra and his colleagues used as inputs for their computer model are badly flawed — based largely on studies 50 and 60 years old that were never intended for such use. And some assumptions are contradicted by some of the very research the authors cite. Worse, the most recent version of the Partners in Flight (PIF) Population Estimates Database (a source cited by the authors) estimates that there are only 3.2 billion birds in the U.S. If the mortality estimates produced by Marra and his co-authors — which they describe repeatedly as “conservative” — were even remotely accurate, our birds would have disappeared long ago. (Just one year later, this same team of researchers estimated that 365–988 million birds die annually as a result of building collisions, [12] further exceeding the PIF estimates and raising additional doubts about the astronomical number of mortalities they attribute to cats.)

Claim:     Cats can pose a threat to public health from potential transmission of diseases, most significantly toxoplasmosis. Toxoplasma is a protozoan parasite that reproduces sexually exclusively in felids. Dispersal into the environment occurs in the form of many millions of microscopic oocysts in cat feces. The oocysts can persist for years and are able to withstand harsh environmental conditions. Unintended hosts, such as gardeners and children, can ingest toxoplasma oocysts and become infected (11 to 22 percent of all Americans are estimated to be infected). Oocysts divide and spread, eventually lodging in various parts of the brain, with the potential to alter brain chemistry. A growing body of literature now strongly suggests that toxoplasmosis infection is responsible for a range of mental illnesses, including schizophrenia, bipolar disorder and increased risk of suicide. Toxoplasma oocysts also infect wildlife and have caused significant mortality in species such as the endangered Hawaiian monk seal and threatened sea otters.

Facts:     Data from the large-scale National Health and Nutrition Examination Survey reveal a significant decrease between 1988 and 2010 in age-adjusted seroprevalence of Toxoplasma gondii among people 12–49 years of age born in the U.S. (1988–1994: 14.1 percent; 1999–2004: 9.0 percent; 2009–10: 6.6 percent). [13] If, as the authors of Cat Wars suggest, there is an “explosion in the number of free-ranging cats wandering America’s urban, suburban, and rural landscapes” [14] and TNR increases the risk of exposure, then we would expect the trend to be increasing, not decreasing. Once again, the authors’ claims are simply not supported by the data.

In 2013, researchers reported that unmanaged “feral” cats are 4.8 times more likely to be exposed to the T. gondii parasite than managed colony cats, and 11.8 times more likely to shed infectious spore-like oocysts in their feces. [15] Feeding community cats would therefore seem to be an effective measure for reducing the likelihood of T. gondii exposure in both cats and, by extension, humans.

While reports of T. gondii and mental illness tend to attract lots of media attention, they routinely fail to demonstrate a causal link. Indeed, researchers conducting a longitudinal study in New Zealand recently found this: “On the whole, there was little evidence that T. gondii was related to increased risk of psychiatric disorder, poor impulse control, personality aberrations or neurocognitive impairment.” [16]

Ear-tipped community catFinally, the connection between domestic cats and T. gondii infection in marine mammals is grossly exaggerated. One 2015 study, for example, found that “spillover from wildlife, not pets” was largely responsible for T. gondii infection among sea otters along the California coast. [17] And the population of Hawaiian monk seals is recovering, with increases around the most populated Hawaiian islands (where the risk of T. gondii-contaminated runoff would presumably be greatest). And as Charles Littnan, the National Oceanic and Atmospheric Administration’s lead scientist for the agency’s Hawaiian Monk Seal Research Program, explained recently, survival rates bode well for future increases: “These are the highest levels that we’ve seen in decades, and in some places, the highest levels in survival that we’ve seen in 30 years.” [18]

Claim:     Most important of all, the book outlines a clear agenda for tackling these problems moving forward (and the consequences of inaction). This agenda includes addressing the persistent issue of pet abandonment, stopping the failed practice of TNR, and removing cats from particularly sensitive conservation areas with highly vulnerable wildlife populations.

Facts:     The main solution provided by Marra and Santella is killing this country’s most popular pet on an unprecedented scale. This unmistakable theme is woven throughout the book — removing “all free-ranging cats from the landscape by any means necessary.” [14] Curiously, the authors emphasize “the importance of spaying and neutering as many cats as possible” [14] and concede that TNR can be effective if done with sufficient rigor — but they nevertheless oppose the practice. Marra and Santella also ignore the various surveys demonstrating broad public support for TNR. [19-21]

Literature cited

  1. APPA, 2013–2014 APPA National Pet Owners Survey, 2014, American Pet Products Association.
  2. Freiwald, A., A. Litster, and H.Y. Weng, Survey to investigate pet ownership and attitudes to pet care in metropolitan Chicago dog and/or cat owners. Prev Vet Med, 2014.
  3. Clancy, E.A., A.S. Moore, and E.R. Bertone, Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats. Journal of the American Veterinary Medical Association, 2003. 222(11): p. 1541–1545.
  4. Kays, R.W. and A.A. DeWan, Ecological impact of inside/outside house cats around a suburban nature preserve. Animal Conservation, 2004. 7(3): p. 273–283.
  5. Lord, L.K., Attitudes toward and perceptions of free-roaming cats among individuals living in Ohio. Journal of the American Veterinary Medical Association, 2008. 232(8): p. 1159–1167.
  6. Levy, J.K., N.M. Isaza, and K.C. Scott, Effect of high-impact targeted trap-neuter-return and adoption of community cats on cat intake to a shelter. The Veterinary Journal, 2014. 201(3): p. 269–274.
  7. Johnson, K.L. and J. Cicirelli, Study of the effect on shelter cat intakes and euthanasia from a shelter neuter return project of 10,080 cats from March 2010 to June 2014. PeerJ, 2014. 2: p. e646.
  8. Medina, F.M., et al., A global review of the impacts of invasive cats on island endangered vertebrates. Global Change Biology, 2011. 17(11): p. 3503–3510.
  9. Fitzgerald, B.M. and D.C. Turner, Hunting Behaviour of domestic cats and their impact on prey populations, in The Domestic Cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 2000, Cambridge University Press: Cambridge, U.K.; New York. p. 151–175.
  10. Royal Society for the Protection of Birds. Are cats causing bird declines? 2016.
  11. Davis, N. Miaow! Row over harm done by domestic cats sends fur flying. The Guardian, 2016.
  12. Loss, S.R., et al., Bird-building collisions in the United States: Estimates of annual mortality and species vulnerability. The Condor, 2014. 116(1): p. 8–23.
  13. Krueger, W., et al., Drinking water source and human Toxoplasma gondii infection in the United States: A cross-sectional analysis of NHANES data. BMC Public Health, 2014. 14(1): p. 711.
  14. Marra, P.P. and C. Santella, Cat Wars: The Devastating Consequences of a Cuddly Killer. 2016: Princeton University Press.
  15. VanWormer, E., et al., Toxoplasma gondii, source to sea: Higher contribution of domestic felids to terrestrial parasite loading despite lower infection prevalence. EcoHealth, 2013: p. 1–13.
  16. Sugden, K., et al., Is Toxoplasma Gondii Infection Related to Brain and Behavior Impairments in Humans? Evidence from a Population-Representative Birth Cohort. PLoS ONE, 2016. 11(2): p. e0148435.
  17. Lafferty, K.D., Sea otter health: Challenging a pet hypothesis. International Journal for Parasitology: Parasites and Wildlife, 2015. 4(3): p. 291–294.
  18. n.a. Hawaiian monk seal population makes slow, but promising recovery. 2016.
  19. Chu, K. and W.M. Anderson, Law & Policy Brief: U.S. Public Opinion on Humane Treatment of Stray Cats, 2007, Alley Cat Allies: Bethesda, Md.
  20. Wolf, P.J. New Survey Reveals Widespread Support for Trap-Neuter-Return. Humane Thinking, 2015.
  21. Wald, D.M., S.K. Jacobson, and J.K. Levy, Outdoor cats: Identifying differences between stakeholder beliefs, perceived impacts, risk and management. Biological Conservation, 2013. 167(0): p. 414–424.


  • feralpower

    Thank you Best Friends, feral cats need you and I love you❤️

  • Maggie

    I believe study reports that are extrapolated, which is normally an accepted scientific tenet, can not account for enough variables to result in accuracy for feral or free-roaming cats. I am a long term cat owner and have lived in both rural and urban areas. I currently have 4 cats. 2 of them are indoor/outdoor. Only One of those has been a fairly efficient hunter. As she has aged, the amount of prey she has hunted has tremendously decreased. And I would be hard pressed to even keep her inside full time!

  • CatfishBigg

    “Pest Fiends of Animals” actually used to keep an online TNR database to document its ‘progress’. The data was, to put it mildly, humiliating. Example, of 100 TNR programs sampled from around the world over a 17 year period, only ONE of them succeeded in sterilizing more than 0.4% of the feral cat populations in their respective areas. That was Oregon, USA which managed to sterilize 4.9% of its estimated 50,000 feral cats. Average percent sterilization, 0.44% (n = 100). At the most conservative estimate of feral cat reproductive rate, that means TNR charlatans were cutting kitty balls and tying kitty tubes at ONE NINE-HUNDREDTH of ONE PERCENT of the rate at which feral cats reproduce. Put another way, Oregon’s phenomenal “success” would be reduced to 0.35% by the next year’s crop of feral kittens, and by at least another order of magnitude by the one after that. What this means is that ‘successful’ TNR is a MATHEMATICAL IMPOSSIBILITY. What it also means is that BFA deleted their online data base out of embarrassment. Usually when real SCIENTISTS realize they’re wrong, they abandon their methods and try another approach. Why hasn’t this happened with TNR charlatans? Why do you keep pursuing this impossible task? Is it because it was never INTENDED to achieve feral cat “ZPG”, let alone actual colony attrition? Is it because you want lots of ‘pets’ but aren’t responsible enough to take care of them in YOUR house, so you foist them on the rest of us?

  • ckessler

    It is apparent that the “researchers” have a bias. The real danger to the earths inhabitants and natural resources are humans. WE ARE THE MOST DANGEROUS SPECIES ON EARTH!!!
    I get so damned tired of human sanctimony!

  • dhkirk

    Thorough analysis – as alwaya. You may also want to consider Marra’s claim about bird predation rate in the UK, briefly (if I recall correctly) he states that 1/3rd of the UK’s bird population are killed by cats each year. I don’t think I’d need a population model to calculate that birds would have been extinct there in the 1950’s !!!!!

  • Kathi McDermott

    The study “confirmed that cats kill an estimated 1.3 to 4.0 (with a median of 2.4) billion birds per year, with the majority of the mortality (69 percent) caused by unowned cats.” Really? I’d love to know their secret for determining whether a free-roaming cat is owned or unowned.