TNR Reality Check

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Positions on Free-Roaming and Feral Cats UPDATED
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Basic Information About TNR
Public Health UPDATED
The Contradictions of TNR
Examples of the Failure of TNR UPDATED
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We base many of our statements on information collected from the following sources. These articles and links help provide the foundation for our argument. We encourage you to research these and related topics in order to make an informed decision about how to respond to the free-roaming and feral cat issue.

Recent Science and News:

NEW Guttilla, D.A. and Paul S. Effects of sterilization on movements of feral cats at a wildland-urban interface. Journal of Mammalogy, 91(2):482-489, 2010.

Superior Court Orders City of LA to Stop TNR Program Pending Envronmental Review

Felines Fatales, excellent Incite article by Ted Williams, in the September-October 2009 issue of Audubon magazine

New video from the American Bird Conservancy - Trap, Neuter and Release: Bad for Cats, Disaster for Birds

For the latest information on Managed Cat Colonies and TNR from the American Bird Conservancy click here.

Longcore et al. Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return. Conservation Biology (2009) pp. 887-894.

View here:

Eight coyotes were captured, radiocollared, and tracked from November 2005 to February 2006 for 790 hours in Tucson, Arizona. Thirty-six coyote-cat interactions were observed. Nineteen resulted in coyotes killing cats. Most cats were killed in residential areas from 2200 hours to 0500 hours during the pup-rearing season. More information below:

Dangers to Public Health:

Eating undercooked meat is one way of acquiring Toxoplasmosis. The source of contamination can be traced back to free-roaming and feral (outdoor) cats that have shed the parasite, Toxoplasma gondii, in their feces. Pigs, sheep, deer, and other animals eat contaminated feed or ingest infected soil and then humans eat those animals.

Toxoplasmosis (a brochure for cat owners from the Centers for Disease Control and Prevention):

Dr. Milton M. McAllister, a professor of pathobiology in the College of Veterinary Medicine at the University of Illinois at Urbana-Champaign, recently published a review of toxoplasmosis in the 9/30/05 issue of the journal Veterinary Parasitology. Dr. McAllister and his colleagues have linked the zoonotic parasite, Toxoplasma gondii, to schizophrenia in humans. This parasite is often carried by feral cats feeding on infected mice. Dr. McAllister urges people to keep pet cats inside and stop feeding strays as a means of reducing this disease in cats and protecting the public from contracting the disease.

More information about his review can be viewed at:

From NPR, SCIENCE OUT OF THE BOX, Sneaky Parasite Attracts Rats to Cats, by David Kestenbaum, All Things Considered, April 14, 2007. Listen to the five minute audio interview. This is fascinating!

A Common Parasite Reveals Its Strongest Asset: Stealth
By Carl Zimmer

Check out this interesting article about toxoplasmosis and cats from the June 20, 2006 issue of the New York Times:

USGS National Wildlife Health Center


See Box 7 page 50

In addition to toxoplasmosis (for which there is currently no vaccine), and viral illnesses, domestic cats carry a large number of bacteria that are harmful to humans and other animals if bitten.

Review the following articles to understand the number of seriously harmful bacteria that are transmitted and to consider the risk that these domestic cats may pose to children, domestic pets, and wildlife.

Talan DA, Citron DM, Abrahamiam FM et al. Bacteriologic analysis of infected dog and cat bites. Emergency Medicine Animal Bite Infection Study Group. N Engl J Med 1999; 340:85-92.

Brook I. Microbiology of human and animal bite wounds in children. Pediatr Infect Dis J 1987; 6:29-32.

Davies HD. When your best friend bites: a note on dog and cat bites. Pediatrics and Child Health 2000; 5(7):381-383.

Powers RD. Mammalian bites. Audiodigest Emergency Medicine 2000; 17(7):7.

Position Statement on free-roaming/unowned/feral cats by the National Association of State Public Health Veterinarians: Click Here.

When Cats Bite: 1 in 3 Patients Bitten in Hand Hospitalized, Infections Common: Click Here.

Dangers to Wildlife:

Do a Little, Save a Lot: Keep Cats Indoors

Hawkins et al, Effect of house cats, being fed in parks, on California birds and rodents, 2004

The number of native predators fluctuates to match the availability of their natural food sources. Not the case for the domestic cat - a subsidized non-native predator. Cat predation appears to affect the sustainability of some species - an excellent reason for not allowing cats to roam. Here is another. As described in this paper, 42% of all cat owners in areas with coyotes reported that coyotes had attacked or killed their cats (Crooks and Soule. Mesopredator release and avifaunal extinctions in a fragmented system. Nature 1999; 400:563-566).

Lepczyk et al. Landowners and cat predation across rural-to-urban landscapes. Biological Conservation 2003; 115:191-201.

There is a concern about the effects of feral cats and feral cat colonies on native wildlife. Although feral cats may be fed, many studies have shown that these cats continue to capture and kill wild prey, including species of special concern (e.g., Hawkins, C.C., W.E. Grant, and M.T. Longnecker. 1999. Effect of subsidized house cats on California birds and rodents. Transactions of the Western Section of The Wildlife Society, 35:29-33).

A study of radio-collared cats in Wisconsin estimated that cats in Wisconsin kill at least 19 million songbirds and 140,000 game birds every year (Coleman JS and Temple SA. 1993. Rural residents' free-ranging domestic cats: a survey. Wildlife Society Bulletin, 21:381(10)).

A study estimate has been made that a population of 44 million outdoor cats would catch and kill 4.4 million songbirds a day (Stallcup R. 1991. Cats: A heavy toll on songbirds-A reversible catastrophe. Observer, A Quarterly Journal of Point Reyes Bird Observatory, 91:8).

The impact of feral cats on wildlife goes beyond rodents and songbirds: a study of cats introduced to an island in the subarctic Indian Ocean found that 2,200 cats were killing 600,000 seabirds annually (van Rensburg, PJ and Bester J. 1988. The effect of cat (Felis catus) predation on three breeding Procellariidae species on Marion Island. South African Journal of Zoology, 23(4):301-305).

The impact of domestic cat (Felis catus) on wildlife welfare and conservation: a literature review. With a situation summary from Israel.

Analyses conducted by Tri-State Bird Rescue and Research, Inc., in Newark, DE have shown that approximately 13-14% of the annual caseload consists of birds that have been injured by cats. Almost two thirds of these are hatching-year birds, but adult birds compose more than one-third of the cat-attack victims treated (Frink L, Smith A, and Frink JA. 1994. Cat Attacks in Wild Birds: Prevalence, Characteristics, and Treatment of Injuries, in Wildlife Rehabilitation vol 12. National Wildlife Rehabilitators Association: St. Cloud, MN. Pp. 55-66).

Biologists at the University of Sheffield use a mathematical model to illustrate that the mere presence of cats could lead to population crashes.

The following three papers were published in the November 2004 issue of the Journal of the American Veterinary Medical Association (JAVMA) and cover a broad spectrum of related issues:

Trap-neuter-release programs: the reality and the impacts [L Winter], 2004; 225:1369

The welfare of feral cats and wildlife [DA Jessup], 2004; 225:1377

Professional, ethical, and legal dilemmas of trap-neuter-release [PL Barrows], 2004; 225:1365

The following paper was co-authored by Dr. Julie Levy, a pro-TNR veterinarian. Note that the paper showed that even two well-funded county-wide TNR programs aided by either a large veterinary school or several private practices failed to reduce the number of feral cats and, in fact, did not even reduce the population growth. How can we expect other smaller programs with fewer resources to be successful?

Foley P et al. Analysis of the impact of trap-neuter-return programs on populations of feral cats. Journal of the American Veterinary Medical Association, December 1, 2005, Vol. 227, No. 11, Pages 1775-1781.

The Fallacy of Territorial Defense:

Ash SJ. Ecological and sociological considerations of using the TTVAR (trap, test, vaccinate, alter, return) method to control free-ranging domestic cat, Felis catus, populations. PhD Dissertation, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, 2001.

Haspel C, Calhoon RE. Activity patterns of free-ranging cats in Brooklyn, New York. J Mammology 1993; 74:1-8.

Dobson R. Frisky cats abandon traditional values. The Independent. London, 2000;8.

The following link will take you to the article, "Should Feral Cats Be Euthanized?":

The information listed above is just a sampling of resources. For more literature and references please go to the following links:

Do not go where the path may lead, go instead where there is no path and leave a trail.

-Ralph Waldo Emerson

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