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Trap-neuter-return (TNR), also known as trap-test-vaccinate-alter-release (TTVAR), is a method of humanely trapping unaltered feral cats, spaying or neutering them, and returning them to the location where they were collected. TNR is promoted by the American Society for the Prevention of Cruelty to Animals (ASPCA) as a humane and more effective alternative to euthanasia for managing and reducing feral cat populations.[1] TNR is opposed by wildlife advocacy organizations, PETA, and conservation scientists.[2][3][4][5] Advocates claim that the procedure works by stopping the birth of new cats in the colony and letting the colony members live out their lifespan, approximately six years for outdoor cats, with their own group. Opponents claim that TNR subsidizes a non-native predator responsible for the deaths of more than fourteen billion birds, mammals, reptiles, and amphibians annually in the United States alone.[6][7]


A feral female recovering from her spay surgery.
Feral kitten, approximately nine months old, with the tip of his left ear removed to indicate he has been trapped and neutered.

Trap-neuter-return begins with the humane trapping of feral cats. The cats are taken (in the trap) to a spay/neuter location for surgery. More and more communities are offering low-cost spay/neuter surgeries for feral cats, but prices vary depending on location. All TNR programs include rabies vaccinations, and some also include providing vaccinations against certain diseases like feline panleukopenia, herpes, and calicivirus. Finally the cat is marked by "eartipping," removing 3/8 inch (1 cm) off the tip of the left ear. Eartipping easily identifies a cat as being neutered and vaccinated, and can often be a lifesaving measure, sparing the cat unnecessary surgery, confinement or euthanasia.[8]

Some programs choose to test cats for feline leukemia virus (FeLV) and/or feline immunodeficiency virus (FIV) prior to sterilization, and euthanize if the test is positive. The value of FIV/FeLV testing is the subject of debate among feral cat advocates, with some stating that testing is an ineffective use of limited funds that otherwise could be used to sterilize more cats, and others holding the position that it is unethical (and inhumane) to release a cat that is carrying a virus that causes deadly disease and that is transmissible to other cats. The ASPCA guidelines for the sterilization of feral cats recommend not testing as the limited resources would be best applied to population reduction.

After the cat is sterilized it is placed back in the trap and allowed to recover from surgery. The feral cat is monitored and cared for in a controlled location, usually the trap inside the home of the colony manager, with food and water. Generally, cats should have 24 hours of recovery time and can be returned to their colony when they are awake, alert, and do not require further medical attention. Some cats may require more extended recovery time, and should be transferred to a holding pen if they require more than 48 hours of recovery.


Supporters of TNR embrace this practice as part of a "no-kill" philosophy. Euthanasia on a massive scale is not fiscally practical. TNR advocates agree that the traditional methods of trapping-and-removing will not work because of a "vacuum effect": As some cats are taken out of their territory, others will move in to replace them, which renders the initial removal ineffective.[9] However, there is little to no scientific evidence to support this claim. If other feral cats are available to do so, the primary factor of whether they will or not is the availability of food: If enough food is present, then any nearby cats may move in.[10]


Studies have been conducted to gauge the effectiveness of TNR. Several of them suggest that the procedure works.[11][12][13][14] A PhD study in North Carolina found that TNR consistently reduced the populations of feral cat colonies by a mean of 36% over two years and with the extinction of one third of the colonies within the same period, while the non-TNR'd colonies increased by a mean of 47%.[15] One peer-reviewed study showed a reduction in numbers of cats with TNR by 66% over an 11 year period.[16]

However, a study by Castillo (2003)[17] found that TNR was ineffective due to feeding locations attracting even more feral cats while also providing a convenient place to illegally dump unwanted cats, although advocates argue that dumping is a separate issue and does not invalidate TNR.[18] A review article by Longcore et al. (2009) argues that TNR advocates are too concerned about cat welfare and not about the effect on indigenous wildlife.[19] The authors argue that populations are not stable and movement of cats is significant between urban areas and nearby woodland. They also state that cats can reach high densities when there is a reliable food source without proper sterilization and management. California State University researchers published mathematical models of feral cats populations suggesting that 71–94% of a population needs to be sterilized for the population to decline, based on case studies of San Diego and Alachua Counties.[20]

Effect on wildlife[edit]

The trap-neuter-return approach is controversial. Many wildlife and bird advocacy organizations argue that TNR does nothing to address the possibility that predation by feral cats could threaten endangered species. TNR groups state that the effect of habitat destruction is caused by irresponsible human development and not by feral cat colonies.

Longcore et al. found that feral cats harm wildlife on continents as well as islands, and that there have been recorded instances of bird extinction from feral cats on islands. Their paper also argues that fragmented ecosystems near urban areas are similar to islands and more susceptible to feral cat damage, and that feral cats in urban areas also pose significant risk to migratory birds. The authors argue that feral cats are exotic and do not fill an existing niche and that even well-fed cats significantly impact on wildlife. The article details population and comparative studies of the adverse effects of feral and free roaming cats on birds and other wildlife. However, longer and more detailed studies need to be done on this subject. The authors also argue that feral cats act as vectors for diseases that can impact domestic cats, wildlife and humans, examples include feline leukemia virus, feline immunodeficiency virus, fleas and ear mites (which are also carried by canines and wildlife), hookworms, roundworms, Bartonella, Rickettsia, Coxiella and Toxoplasma gondii, and that fecal matter has also been shown to degrade water quality.[19]

The International Union for Conservation of Nature states that feral cats have been responsible for the extinction of at least 33 bird species world-wide.[3]:263 However the Royal Society for the Protection of Birds has argued that cats do not pose a significant threat to wild bird populations in the United Kingdom.[21]

See also[edit]


  1. ^ "Position Statement on Feral Cat Management". American Society for the Prevention of Cruelty to Animals. Retrieved 12 January 2014. 
  2. ^ Christopher A. Lepczyk, Nico Dauphine, David M. Bird, Sheila Conant, Robert J. Cooper, David C. Duffy, Pamela Jo Hatley, Peter P. Marra, Elizabeth Stone, and Stanley A. Temple (2010): "What Conservation Biologists Can Do to Counter Trap-Neuter-Return: Response to Longcore et al." Conservation Biology
  3. ^ a b Jim Sterba (13 November 2012). Nature Wars: The Incredible Story of How Wildlife Comebacks Turned Backyards into Battlegrounds. Random House Digital, Inc. p. 259. ISBN 978-0-307-98566-8. Retrieved 11 April 2013. 
  4. ^ American Bird Conservancy: "Cats Indoors".
  5. ^ The Wildlife Society: "Problems with Trap Neuter Release".
  6. ^ Bradley Blackburn: "Roaming Cats Kill up to a Billion Birds a Year, American Bird Conservancy Reports", The fourth letter to the movement of TNR movement, implicit in its work is "M" for maintenance of the colony. Humans - often but not always - who TNR the colony also provide food and medication to control parasites. Feral Colonies form around food sources; this is why they are usually found near dumpsters behind restaurants etc. NPR recently broadcast results of a tracking study indicating the average cat is able to catch less than 14% of what ever it stalk. PETA opposes TNR based on the dangers of living without human guardianship. Their literature points to case after case of cats being poisoned, burned, shot with arrows, etc. Cats that allow humans to get close enough to pick them up and abuse them are generally socialized to humans to begin with. True ferals generally conceal themselves during daylight hours shunning contact with humans in any case. PETA also opposes cruel confinement for any species. Depriving any living thing ~ including felines kept locked indoors~ opportunity to feel prt of the natural world could be characterized as cruel confinment. .'ABC News.
  7. ^ Angier, Natalie. "That Cuddly Kitty Is Deadlier Than You Think". New York Times. Retrieved 29 January 2013. 
  8. ^ "Frequently Asked Questions". Retrieved 21 November 2010. 
  9. ^ Tabor, Roger (December 8, 1983). The Wild Life of the Domestic Cat. Arrow Books Ltd. p. 224. ISBN 0-09-931210-7. 
  10. ^ Tabor, Roger (April 30, 2003). Understanding Cat Behavior. David & Charles. p. 144. ISBN 0-7153-1589-7. 
  11. ^ Hughes, Kathy L.; Margaret R. Slater (January 2002). "Implementation of a Feral Cat Management Program on a University Campus". Journal of Applied Animal Welfare Science. doi:10.1207/S15327604JAWS0501_2. Retrieved February 14, 2011. 
  12. ^ Levy, Julie K.; David W. Gale,‌ Leslie A. Gale (January 2003). "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. doi:10.2460/javma.2003.222.42. Retrieved February 14, 2011. 
  13. ^ Hughes, Kathy L.; Slater, Margaret R. (2002). "Implementation of a Feral Cat Management Program on a University Campus". Journal of Applied Animal Welfare Science 5 (1): 15–28. doi:10.1207/S15327604JAWS0501_2. 
  14. ^ Zaunbrecher, KI; Smith, RE (1993). "Neutering of feral cats as an alternative to eradication programs.". Journal of the American Veterinary Medical Association 203 (3): 449–52. PMID 8226225. 
  15. ^ Michael K. Stoskopf and Felicia B. Nutter, "Analyzing approaches to feral cat management-- one size does not fit all," JAVMA, Vol 225, No. 9, November 1, 2004
  16. ^ Julie K. Levy, David W. Gale and Leslie A. Gale, "Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population", JAVMA, Vol 222, No. 1, January 1, 2003 [1]
  17. ^ Trap/Neuter/Release Methods Ineffective in Controlling Domestic Cat "Colonies" on Public Lands
  18. ^ The Truth About Trap-Neuter-Return and Feral Cat Colony Movement
  19. ^ a b LONGCORE, TRAVIS; RICH, CATHERINE; SULLIVAN, LAUREN M. (2009). "Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return". Conservation Biology 23 (4): 887–894. doi:10.1111/j.1523-1739.2009.01174.x. 
  20. ^ Patrick Foley, Janet E. Foley, Julie K. Levy, "Analysis of the impact of trap-neuter-return programs on populations of feral cats," JAVMA, Vol 227, No. 11, December 1, 2005
  21. ^

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