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Trap-neuter-return (TNR) is a program through which free-roaming cats (not belonging to particular humans) are humanely trapped, sterilized and medically treated, and returned to the outdoor locations where they were found. If those locations are deemed unsafe or otherwise inappropriate, feral cats (unsocialized to humans) are relocated to farmyard homes. Kittens still young enough to be socialized and friendly adult cats are typically placed in foster care for eventual adoption into homes as companion animals rather than returned to the outdoors. Cats found suffering with terminal or untreatable illnesses or injuries are humanely euthanized.
TNR is endorsed by the American Society for the Prevention of Cruelty to Animals (ASPCA) as "the most humane, effective and financially sustainable strategy for controlling free-roaming cat populations"  and "the only proven humane and effective method to manage feral cat colonies." The Humane Society of the United States has also endorsed "community-based Trap-Neuter-Return (TNR) programs with on-going responsible management as the most viable, long-term approach available at this time to reduce feral cat populations." The American Humane Association is another supporter of TNR. In Canada, the Canadian Federation of Humane Societies supports TNR, stating that the care of feral cats "is society's responsibility" as their wild nature is the result of human neglect. The U.K.'s Royal Society for the Prevention of Cruelty to Animals (RSPCA) supports "trapping and neutering of feral cats where local charities have the capacity to do so." Worldwide supporters include the World Animal Foundation, based in Oneida, Kentucky, and the International Companion Animal Management Coalition.
North American wildlife organizations including the American Bird Conservancy and The Wildlife Society oppose TNR. They dispute its effectiveness at reducing feral cat populations, and claim that free-roaming cats are responsible for much of the decline in bird populations over the last number of years, killing 1.4 to 3.7 billion birds annually in the U.S. Rather than TNR, they recommend that free-roaming cats be taken to local animal shelters. The Wildlife Society "support[s] and encourage[s] the humane elimination of feral cat populations, including feral cat colonies, through adoption into indoor-only homes of eligible cats and humane euthanasia of unadoptable cats."
TNR advocates counter that cat predation is inflated. They argue that removing feral cats en masse can harm the environment and even birds; euthanizing healthy cats is inhumane, and even more expensive for public officials than TNR; and research and experience of TNR shows that community cat populations indeed decline. In the U.K., The Royal Society for the Protection of Birds states that there is no evidence that cat predation "is having any impact on bird populations UK-wide".
TNR is sometimes described as trap-neuter-release, changing the last word of the acronym. This wording appears to have been the first version of the TNR acronym. The word "return" emphasizes that most feral cats are returned to their original locations under this program, and is the word most in current use. Some programs also go by other acronyms: TNVR (trap-neuter-vaccinate-return) adds emphasis to the process of vaccinating the cats for diseases like rabies before their return to the outdoors. TNRM (trap-neuter-release-maintain) adds the word "maintain," emphasizing the final part of the program, where caregivers feed and monitor the feral cats after they are returned to their territories. TTVAR (trap-test-vaccinate-alter-release) adds details about testing undertaken for serious illnesses, but this acronym is not in wide usage.
- 1 History
- 2 Methodology
- 3 Legal issues
- 4 Rationale and effectiveness of TNR
- 5 Effect on wildlife
- 6 See also
- 7 References
- 8 Further reading
- 9 External links
The earliest documented practice of trap-neuter-return was in the 1950s, led by animal activist Ruth Plant in the U.K.:2 In the mid-1960s, former model Celia Hammond gained publicity for her TNR work:2 "at a time when euthanasia of feral cats was considered the only option." Hammond "fought many battles with local authorities, hospitals, environmental health departments" but stated that she succeeded over the years in showing that control "could be achieved by neutering and not killing."
In 1975, Ruth Plant:2 founded the Cat Action Trust to help feral cats using TNR. From 1978 to 1979, biologist Roger Tabor mapped the distribution of 153 known feral cat colonies in central London, some being managed by the Cat Action Trust.:91
In 1980, the Universities Federation for Animal Welfare (UFAW) organized the first international scientific symposium on "The Ecology and Control of Feral Cats" in London, where TNR experiences in the U.K. and Denmark were documented.:2 The symposium was considered a "watershed occurrence" where attitudes toward feral cats began to shift toward humane treatment. In 1982, UFAW published a booklet promoting TNR: Feral Cats: Suggestions for Control.:6
The Cat Action Trust reports that many thousands of feral cats have been neutered in subsequent years. In 1986, Hammond founded the Celia Hammond Animal Trust to continue her work with feral cats, taming and rehoming hundreds of feral kittens each year; and offering low cost neutering, which by 2014 was reported to have sterilized nearly 400,000 cats.
In 2008, the Scottish Wildcat Association began utilising trap-neuter-return as a way to prevent hybridisation between feral cats and the locally endangered Scottish wildcat as part of the Wildcat Haven project. In 2014 they announced over 250 square miles of remote wildcat habitat was now effectively feral cat free  through neutering the feral population, farm cats and pets with the support of the local community and local welfare groups.
Soon after visiting Venice, Italy, in 1965, Helena Sanders and Raymonde Hawkins initiated a program offering veterinary help, often for neutering, to assist cat caretakers there.:48 After initial resistance from local animal protection societies, neutering schemes for city cats were accepted in many parts of Italy.:48 The cats of Venice and Rome became famous as a result of the publicity given to their neutering programs.:523 Since 1988, killing feral cats has been illegal in the Latium Region, which includes Rome. Since August 1991, feral cats have been protected throughout Italy when a no kill policy was introduced for both cats and dogs. Feral cats have the right to live free and cannot be moved from their colony; cat caretakers can be formally registered; and TNR methods are outlined in the national law on the management of pets.
TNR was practiced in Denmark in the mid-1970s, as reported at the 1980 UFAW symposium in London.:3 The Danish Cat Protection Society developed the practice of both tattooing and ear-tipping the ear of the neutered cats to identify them.:187
In the mid-1970s, Louise Holton worked with the Johannesburg SPCA on TNR programs in that city. In 1991, Adele Joffe founded Friends of the Cat, a TNR organization in Johannesburg. Holton continued to help feral cats in South Africa as part of her outreach efforts with Alley Cat Rescue, founded in 2001.
In 1977, Michel Cambazard began to advocate for free-living cats at the Montmartre Cemetery in Paris, where the cats were routinely euthanized. In 1978, the city issued a Declaration of Rights of the Free-living Cat. In that year, Cambazard founded École du Chat and TNR'd its first cat, continuing to help thousands of cats in the following years.
TNR goes back to the late 1960s in the U.S. In approximately 1970, a group in Ocean County, New Jersey began its efforts.:7 In 1984, AnnaBelle Washburn introduced TNR to Martha's Vineyard, Massachusetts.
In 1989, Nathan Winograd and others formed the Stanford Cat Network to assist about 1,500 cats at Stanford University in California, in probably the first formal TNR program at a U.S. campus.:44 Within 15 years, the population at Stanford University had dropped to 85 cats.:44 By 1990, other groups were also practicing TNR in Idaho, Nevada, Pennsylvania, and Colorado.:7
In 1990, Louise Holton and Becky Robinson discovered an alley with 56 cats and two smaller colonies in Washington, D.C., and neutered all the cats.:8 Deluged by requests for help,:8 and concerned for cats routinely being killed by animal control agencies and shelters, Holton and Robinson founded Alley Cat Allies. They developed extensive educational materials, and organized national conferences beginning in 1994.:9 They started a Feral Friends Network, which has a global reach. The organization grew to 500,000 supporters and a staff of over 40 in 2014. Holton left in 2001 to found Alley Cat Rescue.
In the 1990s, a number of programs to help feral cats were initiated:
- In 1992, San Diego's Feral Cat Coalition developed the first high-volume feral cat sterilization program, where up to 150 cats were sterilized in a single day with the help of volunteer veterinarians and other volunteers.:44 Other communities followed, including Operation Catnip in Raleigh, North Carolina in 1997, and Operation Catnip in Alachua County, Florida in 1998.
- In 1993, led by Richard Avanzino,:10 the San Francisco SPCA started a Feral Cat Assistance Program, offering free sterilization, advice and supplies to cat caretakers.:44 The program was one of several reforms to create a no kill community.:180
- In 1994, PetSmart Charities began to provide grants toward sterilization programs for free-roaming cats and other animals; the organization's website stated in 2014 that more than 2 million spay or neuter surgeries have been funded.
- In 1995, the Doris Day Animal League (DDAL) created the first annual "Spay Day USA" on the last Tuesday of each February, which continues to help many feral cats and other animals as World Spay Day after the DDAL's merger with the Humane Society of the United States in 2006.
- In 1998, the Feral Cat Coalition of Oregon purchased a mobile clinic,:44 which by August 2014 had neutered 70,000 cats.
- In 1999, Maddie's Fund, the family foundation of Dave Duffield and his wife Cheryl,:8 began to provide grants for large-scale neutering of feral cats. Between July 1999 and May 2002, 170,000 cats were neutered by over 1,000 veterinary members of the California Veterinary Medical Association in a $12 million project.:42 Other programs were added, such as low cost sterilization,:3 and research on shelter medicine;:6 with the goal of helping to build a no kill nation.:3
In Palm Beach County, Florida, a project called Countdown to Zero (C2Z), Project Catsnip was organized as a collaboration between government agencies, businesses, volunteers and residents working together to end euthanasia of feral cats in the community through spaying and neutering/ TNR. Together the community is using this approach to reach their goal of zero cats euthanized in the county.
On October 16, 2001, Alley Cat Allies created the first annual National Feral Cat Day on the 10th anniversary of its incorporation:8 "to raise awareness about feral cats, promote Trap-Neuter-Return, and recognize the millions of compassionate Americans who care for them." The event has attracted international participants.
In 2001, under the leadership of Nathan Winograd, Tompkins County, New York became the first no kill community in the U.S.,:180 "saving 100 percent of healthy and treatable animals, and 100 percent of feral cats".:180 In the No Kill Equation, a "roadmap to no kill" developed by Winograd, TNR is one of the essential elements.:4 Many communities followed this strategy in subsequent years.
In 2008, a grant from Best Friends Animal Society supported a Feral Freedom program in Jacksonville, Florida, that saw the end of killing stray and feral cats in that city. The program, conceived by Rick Ducharme of First Coast No More Homeless Pets, "has feral cats trapped by Jacksonville Animal Control bypass the shelter entirely in favor of being spayed or neutered and returned to the location where they were trapped." Similar programs were later implemented in Albuquerque, New Mexico, DeKalb County, Georgia, San Antonio, Texas, Baltimore, Maryland, Salt Lake City, Utah, Philadelphia, Pennsylvania and many other communities.
TNR efforts in the U.S. have also encountered opposition. Traditional shelters disagreed with TNR, including the Humane Society of the United States,:68 which later reversed its position. The majority of traditional shelters continue to euthanize feral cats. Wildlife groups such as the American Bird Conservancy blame cats for much of the reduction in U.S. bird populations, and in 1997 began its "Cats Indoors" campaign.:18 TNR has gained increasing support over the years.
In the 1980s, the Greek Animal Welfare Fund initiated the neutering of stray cats in Athens, supported by individuals in the U.K.:522 The organization continues to be active, organizing a mass neutering drive for stray cats in Athens for October 2014.
In 1986, AnnaBelle Washburn worked with Tufts University's School of Veterinary Medicine to sterilize feral cats on Virgin Gorda in the British Virgin Islands, "in one of the earliest partnerships between veterinary medicine and grass-roots organizations to improve the lot of feral cats.":44
Canada's best known TNR effort was at the Cat Sanctuary of Parliament Hill in the nation's capital, Ottawa, Ontario, where cats were employed for pest control until 1955. Various people fed the remaining cats until 1970, when Irene Desormeaux began feeding them at their eventual colony location. In the mid 1980s, Rene Chartrand built wooden housing for the cats and helped with their care, taking over when Desormeaux died in 1987. In 1997 other volunteers joined in, and the structures were rebuilt. In a brutal winter, "the cats survived marvellously cuddling up four or five at a time in the condos." However, neutering all the cats only occurred in the last ten to fifteen years of the sanctuary's operation. In 2013, the colony closed when the last four cats were adopted into homes.
In 1989, Carol Reichert founded the Richmond Animal Protection Society (then Richmond Homeless Cats), to help feral cats in Richmond, British Columbia. Soon 43 feeding stations were being tended in Richmond and south Vancouver. In 1999, space was donated for a shelter, which became Canada's largest cat sanctuary, including space for cats with feline leukemia and feline AIDS. The organization worked to spay and neuter many animals and worked to prevent pets from entering shelters. Determined to "end needless euthanasia", the organization made a successful bid for the city's animal control contract, and in 2007, "implemented a no-kill policy for the animals regardless of age, medical needs or adoptability".
In 2000, Maria Soroski and Karen Duncan founded the Vancouver Orphan Kitten Rescue Association (VOKRA) in Vancouver, British Columbia. They first planned to care for very young, mainly bottle-feeding kittens, who rarely survived if found without a mother cat. They soon found that older kittens would do better in foster care, and then included mother cats, both tame and feral. Care provided to feral cats includes caring for pregnant feral mothers through birthing and until their kittens are weaned. By 2014, the organization had grown to over 350 foster homes helping 1,800 cats annually. Soroski said they had "virtually eliminated feral cat colonies in Vancouver and Burnaby", and had recently begun the same work in Surrey.
In 2005, Pierre Filitreault began helping feral cats at a Halifax, Nova Scotia dockyard on a Canadian Armed Forces base. Disappointed with what happened with two starving kittens he took to a shelter, he set up a TNR program, forming Pierre's Alley Cat Society in 2007. The Department of National Defense paid to have the cats neutered.
In 2000, the Hong Kong SPCA began a TNR program, called a Cat Colony Care Program (CCCP), in Hong Kong. In 2014, the organization's website reported a reduction in euthanasia from 40,000 cats in 1963 to 5,000 cats annually.
The first trigger for a trap-neuter-return program is when free-roaming cats or kittens are seen in need and/or not having been neutered. A TNR program approaches the situation using the following recommended steps:
- Assess the cats and their environment. Do they appear to be stray or feral; are there kittens and/or nursing mothers; are there ill or injured cats? Plan ahead for the care to be provided after trapping.:6
- Communicate with neighbours and any caretakers. Build good community relations, working to address the concerns of others.:5:16
- Establish a regular feeding schedule. This may involve providing feeding stations and winter shelters.:7:13
- Secure a holding/recovery area where the cats can wait for surgery (if not immediate) and recover after surgery.:11:14
- Find and coordinate with a veterinarian or clinic to perform the surgery and provide other medical treatment.:7
- Assemble trapping supplies, including humane traps, newspapers and other useful materials.:11:68
- Withhold food (but not water) for about 24 hours before trapping, with the cooperation of caregivers and neighbours.:14
- Bait and set the traps in a safe location, using as many traps as there are cats in the colony needing trapping.:67
- Wait patiently nearby but out of sight, for cats to enter the traps and the traps to close.:15:75
- Quickly cover each occupied trap with a cover or sheet, which helps to calm the cat within.:15:76
- Check whether each trapped cat is already owned or neutered (ear tip; identification tattoo or microchip; lost pet databases and ads), and take appropriate action.
- If trap occupants are wildlife, carefully release them.:88
- Safely transport the cats in their traps to the clinic or holding area.:16
- If a cat is too fearful or savvy of the regular box trap, try alternate traps and methods.:91
- Provide extra care for cats not yet ready for surgery. Cats in poor condition may need to receive medical attention, gain weight and strength before surgery.:109 Young kittens may be socialized in foster care, which prevents their becoming feral. Nursing mother cats may be kept with their kittens (and even other orphaned kittens) until the kittens are weaned. "Kittens can be safely spayed or neutered at eight weeks, or as soon as they weigh two pounds (and are healthy)."
- When ready, a veterinarian performs spay or neuter surgery and provides other medical attention as needed. Multiple surgeries may be done in high volume clinics.
- During the surgery of feral cats, ear-tipping (removing 3/8 inch or 1 cm from the tip of the left ear; proportionally smaller in a kitten) identifies that the cat has been neutered and treated, when later seen from a distance.
- Vaccinations are provided as arranged in advance. Common vaccines include rabies and FVRCP, "the 'distemper' (panleukopenia) and respiratory virus vaccine".
- Cats found suffering with terminal or untreatable illnesses or injuries are humanely euthanized.
- When the vet deems that the cats are ready to leave the clinic, transport them to the recovery area, and monitor them for at least 24 hours.:17
- If needed, provide further nursing care (e.g. administering medications; providing recovery time from more complex surgery such as amputation).:109
Returning: The cats go home
- If the original colony location is safe, transport the feral cats there and safely release them from their traps or carriers.:18
- If the location is not safe for feral cats, make other arrangements for farmyard homes.:127
- Keep tame cats and kittens in foster care until they are adopted. If there are insufficient resources to foster or shelter, the cats may be returned to outdoor colony locations in the same manner as feral cats.
- Keep detailed records of the cats assisted,:5 and clean the traps and materials used.
- Caregivers monitor the outdoor colony locations, providing food, shelter, and medical care, and watching for any new abandoned cats requiring trapping. Some communities with "Feral Freedom" programs return cats without ongoing monitoring by caregivers.
Early in TNR work, some groups did routine testing for the feline leukemia virus (FeLV) and the feline immunodeficiency virus (FIV) prior to the neutering surgery. This practice is no longer recommended, due to problems such as unreliable results, the high cost of testing, and the low incidence of the viruses.:120
The legal status of community cats varies from location to location.
Since 1988, killing feral cats has been illegal in Rome, Italy, and the Latium Region which includes Rome. Since August 1991, feral cats have been protected throughout Italy when a no kill policy was introduced for both cats and dogs. Feral cats have the right to live free and cannot be moved from their colony, and cat caretakers can be formally registered. TNR methods are outlined in the national law on the management of pets.
In a January 2013 legal brief, Alley Cat Allies found that at least 240 municipal or county governments in the U.S.A. had enacted ordinances supporting TNR; a ten-fold increase from 2003. New Jersey, California and Texas had the highest number of local ordinances. New York City-based Neighborhood Cats found local ordinances in 24 states. Model ordinances are available from Neighborhood Cats, Alley Cat Allies, and the No Kill Advocacy Center. Many U.S. communities with ordinances favorable toward TNR are described in the list of governments supporting trap-neuter-return.
Sometimes governments have been sued to try to block their TNR efforts. In December, 2010, an injunction was granted to prevent a planned TNR program of the City of Los Angeles until an environmental review was completed under the California Environmental Quality Act. The judge did not rule on any environmental issues or prohibit other organizations from doing TNR in the city.
Sometimes cat caretakers have been prosecuted for taking care of feral cats, where local ordinances did not allow for their activities:
- In 2013, the Virginia Supreme Court found a zoning ordinance overbroad when Henrico County charged Susan Mills for caring for feral cats, which the County said was not a permitted activity under the zoning. A circuit court judge had ordered her to stop feeding the cats, but that part of the decision was not enforceable.
- In 2012, 78-year-old Dawn Summers was sentenced to community service for hoarding, as she was feeding up to 27 community cats within a managed colony in a city-sanctioned program in Biloxi, Mississippi. Alley Cat Allies criticized the decision, stating that the community cats should not have been considered owned by the caregiver.
- In 2011, charges against Danni Joshua of Vandercook Lake, Michigan for "allowing animals to run loose" were dismissed when she agreed to have her colony of 15-20 cats relocated.
Sometimes opponents of feral cats are prosecuted for trying to harm or kill cats or kittens contrary to animal protection laws:
- In December 2011, wildlife biologist Nico Dauphiné received a suspended sentence for attempting to kill feral cats with rat poison in Washington, D.C.
- In 2007, Jim Stevenson stood trial for shooting a cat from a colony in Galveston County, Texas. Stevenson observed the colony cats hunting endangered piping plovers in the area. The trial resulted in a hung jury because of a gap in the law stating that ownership of the animal had to be proven, an issue which has since been resolved.
Allie Phillips, director of the National Center for Prosecution of Animal Abuse, states that stray and feral cats are often seen as unsympathetic, and less worthy of the legal protection which she believes they merit.
The City of Toronto, Ontario, has included TNR in its animal services for some years, and enacted a bylaw specifically addressing TNR in 2013. Toronto Animal Services offers spay and neuter clinics for feral cats, and is a member of the Toronto Feral Cat Coalition. Other governments within Canada with laws or policies supporting TNR are described in the list of governments supporting trap-neuter-return.
Less positive were Merritt, British Columbia officials, when in January 2012, a bylaw officer removed cat food and asked the Royal Canadian Mounted Police to consider criminal charges against those feeding the community cats. One writer complained that "Taking food away, particular in the dead of winter only exacerbates the problem by encouraging the cats to forage for food in a wider area. And ultimately, starvation can occur, which again, is considered neglect, and certainly could worsen the City's reputation." No charges were laid, but the rescue group's business license was revoked and it was forced to move from its storefront location.
In Canada, it is an offence under the Criminal Code to intentionally cause unnecessary pain, suffering or injury to an animal. Poisoning animals is specifically prohibited. It is also an offence to threaten to harm an animal belonging to someone else. Most provinces and Territories also have their own animal protection legislation.
Rationale and effectiveness of TNR
Reduced population over time
Various long-term studies have shown that TNR is effective in stopping reproduction and reducing the population over time. An eleven-year study of a TNR program at the University of Central Florida achieved a population decrease of 66%, from 68 cats in 1996 (when the census was first completed after some trapping); to 23 cats in 2002. No new kittens were born after 1995, and newly arrived stray or abandoned cats were neutered or adopted to homes.
A ten-year study of 103 colonies in Rome, Italy showed decreases within the colonies from 16% to 32%, with the highest number for colonies neutered 6 years before the study began.:5 However, Natoli concluded that "This suggests that all these efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy."  Population decreases are expected when at least 71% to 94% of the cats are neutered.:1779 TNR advocates also frequently cite a large-scale program on 103 cat colonies in Rome. Trapping and neutering decreased the populations of 55 cat colonies there, while the other 48 colonies either gained population or stayed the same.
In many cases, TNR has resulted in colonies closing when the last remaining cat died or was adopted. In the U.K., a TNR program at Stoke Mandeville Hospital ended with all the neutered outdoor cats having died, with none coming to take their place.:522 TNR efforts in London's Fitzroy Square in the late 1970s resulted in the colony ending by 1990 with all the cats having died.:522 The cat sanctuary of Parliament Hill in Ottawa, Ontario, Canada, closed in January 2013, when the four remaining cats were adopted into homes. One colony had already become extinct and another was approaching extinction within two years, in a study of 12 colonies in rural North Carolina.:1363
TNR efforts may be hampered if colony locations are made public. An early 2003 study by Castillo of two colonies in popular public parks of Miami-Dade County, Florida revealed that highly visible, well-fed cat colonies attracted illegal abandonment of additional cats, including numerous kittens and females with litters.:252:1358 Despite dedicated efforts to trap and remove the newcomers as well as trap the existing cats, there was a slight increase in population from 81 to 88 cats over the year studied.:251:1358 Community strategies to reduce abandonment in general include providing low cost spaying and neutering for owned cats;:5 improved pet retention programs, and expansion of no-kill animal sheltering.:1358
Improved outcomes for cats: Life vs. death
The typical outcome for a feral cat taken to a traditional shelter which does not practice no kill sheltering is euthanasia. This is often the outcome for timid or even friendly stray cats as well;:1357 a study identified euthanasia in shelters as the leading cause of death of cats.:1359
Since Santa Clara County, California began TNR in 2011, the county reported that "Thanks to this program, the shelter saw a 15% reduction in cat intake and an amazing 65% reduction in cat euthanasia." In a TNR program in Orange County, Florida, the numbers of cats euthanized decreased 18% in a six-year period after starting TNR.:292
In September 2014, Johnson County, Indiana officials reported greater satisfaction with having saved the lives of hundreds of healthy cats in the program's first year. "We're not killing cats.... Not killing a healthy animal is always the right thing to do."
Improved outcomes for cats: Quality of life
TNR programs improve the welfare of the cats involved in many ways. They prevent the birth of kittens, who would be at risk of an early death in the wild.:1359 Adult female cats are no longer burdened with cycles of repeatedly giving birth to and caring for kittens while fending for themselves. Medical conditions such as infections, dental issues, and flea treatments are attended to when the cats are neutered.:115 Spaying and neutering also increases their life expectancy;:35 the cats are no longer subject to certain cancers, and the chances of being hit by a car or injured in a fight drop a great deal.
When programs provide for feral kittens to be socialized and adopted, and for friendly cats to be adopted, the welfare of those cats is improved.:133 Cats returned to their original location are fed, monitored and receive ongoing care from caregivers; including being re-trapped if further medical needs arise. Their health measurably improves, as they gain weight after being neutered,:212 while having ample opportunity for exercise.:210 One study suggests that although TNR "may not meet the gold standard of care desired for pet cats, it appears that sterilized feral cats can enjoy an extended period of good quality of life".:1359
Neutering cats makes them less likely to roam, spray urine and fight; resulting in fewer nuisance complaints.:16 After starting a TNR program in December 1995, Orange County, Florida received fewer complaints about cats, even after broadening the definition of a nuisance complaint.:296 A TNR program at Texas A&M University in 1998-2000 resulted in fewer complaints, showing that the remaining cats were less of a nuisance than they were previously.:25
While neutering cats is costly, euthanizing them costs more.:8 In Orange County, Florida, the average cost of impounding and euthanizing a cat was $139; while the average cost of surgery was $56.:294 With 7,903 feral cats neutered over 6 years starting in December 1995, the county saved $656,000.:295
In Port Orange, Florida a TNR program started in 2013 in the city's business areas resulted in fewer stray cats and money saved. In the first year, 214 cats were sterilized for $13,000, which was much less than over $50,000 spent in 2010, when most of the impounded cats were euthanized. A further estimated $123,000 was saved for not having to impound the offspring of the now spayed cats.
Improved morale and public support
TNR programs are able to garner stronger public support than programs that result in euthanasia.:49 In 2007, Alley Cat Allies commissioned a survey by Harris Interactive, which found that Americans overwhelmingly (81%) considered it more humane to leave a stray cat outside to live out his life rather than having the cat caught and killed.:1 The number was still high (72%) if the person knew that the cat would die when hit by a car in two years' time:2 (although the chances of being hit by a car are much less when a cat is neutered.)
In London area hospitals in the U.K., patients resisted attempts to trap feral cats for euthanasia, but took a great interest in TNR programs; even offering to pay the veterinary fees out of their own pocket money.:521 A TNR program in San Quentin State Prison in California, replacing the practice of euthanizing 100 to 250 cats each year, resulted in benefits to the inmates and staff, including "less violence and tension as well as being able to 'model relatedness' to other species and individuals".:51
In Orange County, Florida, a TNR program started in December 1995 improved the morale of everyone involved; citizens "who previously felt overwhelmed by the dilemma of feral cats they saw in their neighborhoods now feel empowered and able to make a difference in these cats' lives.":297 At the same time, county animal services staff and citizens concerned about the cats were described as viewing each other "with a new perspective and understanding rather than as adversaries.":297
Alternatives ineffective and inhumane
Doing nothing can result in the numbers of feral cats increasing. A study of six managed colonies in rural North Carolina showed a 36% decline in population over two years, while three control colonies without TNR increased by 47% on average.:1363 Further, animal welfare problems such as high rates of kitten mortality continue to occur.:1362 One study suggests that "While still fairly common, this is not a responsible or constructive choice.":48
Removal is an alternative to TNR control their population.:1780 Eradication programs "often require years to accomplish and hundreds of hours of work and are only successful in closed populations where no new cats can arrive.":48 Further, methods used often involve poisoning, shooting, hunting, and other methods considered animal cruelty in many North American jurisdictions. Trapping and removal of cats by euthanasia has been used in many communities, but almost never results in a permanent decrease in the cat population.:48 "It is extremely difficult to remove every cat in a particular location, and most locations are not sufficiently isolated to prevent migration of new cats into the ecological vacuum created by cat removal. If there is sufficient food and shelter, new cats will move in from nearby areas, and survivors of the removal program will continue to reproduce until the maximum carrying capacity is reached again.":48 Many local and state governments have turned to TNR as a more effective and humane approach to control feral cat populations.:11
Effect on wildlife
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.
In the U.K., The Royal Society for the Protection of Birds states that there is no scientific evidence that cat predation "is having any impact on bird populations UK-wide. This may be surprising, but many millions of birds die naturally every year, mainly through starvation, disease, or other forms of predation. There is evidence that cats tend to take weak or sickly birds ... Those bird species that have undergone the most serious population declines in the UK (such as skylarks, tree sparrows and corn buntings) rarely encounter cats, so cats cannot be causing their declines. Research shows that these declines are usually caused by habitat change or loss, particularly on farmland." This evidence is despite the common practice in the U.K. of allowing cats access to the outdoors, which is recommended to prevent feline obesity,:138 and behavior problems and other health problems arising from confinement stress.:121
U.K. biologist Roger Tabor states that "studies from all around the world have found that cats catch relatively few birds compared to small mammals.":135 Moreover, city cats have smaller ranges; in his research, Tabor found "the average annual catch of the average London cat to be two items instead of the fourteen of a village cat.":135 Tabor comments about some of the challenges of stalking birds for cats: "From the cat's point of view not only do birds not play fair by flying and having eyes that can see beyond the back of their heads, but they can positively cheat by using loud alarm calls and throw the cat's chances of catching any others.".:123
This study has limited applicability to North American birds and wildlife, however. Cats are a domesticated species that did not exist in North and South America prior to European contact.
- Overpopulation in domestic animals
- Spaying and neutering
- List of governments supporting trap-neuter-return
- No Kill Equation
- "'Community cat' is an umbrella definition that includes any un-owned cat. These cats may be 'feral' (un-socialized) or friendly, may have been born into the wild or may be lost or abandoned pet cats. Some community cats are routinely fed by one or more community members, while others survive without human intervention. Whatever a cat's individual circumstances, the term 'community cat' reflects the reality that for these cats, 'home' is within the community rather than in an individual household." Kate Hurley and Julie Levy, Maddie's Institute: "Feline Shelter Intake Reduction Program FAQs", January 2013.
- for example, Kitsap Humane Society, Silverdale, WA, "BARN CAT PROGRAM", accessed June 19, 2014.
- "Whenever possible, adoptable cats and kittens should be removed from a feral colony for placement in good homes." "Neighborhood Cats TNR Handbook, 2nd edition: The Guide to Trap-Neuter-Return for the Feral Cat Caretaker", Bryan Kortis, Neighborhood Cats, 2013, p. 133.
- "At Neighbourhood Cats, we euthanize cats only if they are actively ill, suffering and terminal." Ibid., p. 124.
- "Position Statement on Feral Cat Management", American Society for the Prevention of Cruelty to Animals, accessed June 20, 2014,
- "Feral Cats FAQ", ASPCA, second paragraph, accessed June 20, 2014. Resources provided here on TNR and feral cats.
- "HSUS Position Statement: Trap-Neuter-Return (TNR) Humane Society of United States, March 20, 2006. Many resources are offered on TNR:"What You Can Do To Help Feral Cats", Humane Society of the United States, July 3, 2013, accessed June 20, 2014.
- "American Humane Association: Animal Welfare Policy and Position Statements", p. 9, accessed July 17, 2014.
- "Feral Cats", The Canadian Federation of Humane Societies, accessed June 23, 2014.
- "Stray and Feral Cats", Royal Society for the Prevention of Cruelty to Animals, accessed June 23, 2014.
- "Trap-Neuter-Return: Saving Feral Cats", World Animal Foundation, accessed June 23, 2014
- "Humane Cat Population Management Guidance", International Companion Animal Management Coalition, accessed July 19, 2014.
- The American Bird Conservancy has an extensive "Cats indoors" campaign to educate the public about the risks free-roaming cats pose to wildlife and humans: "Cats Indoors: Better for Cats. Better for Birds. Better for People."
- "Problems with Trap-Neuter-Release", The Wildlife Society, updated Feb. 2011. See also "Final Position Statement: Feral and Free-Ranging Domestic Cats", The Wildlife Society, "Approved by Council August 2011. Expires August 2016". The Wildlife Society is based in Bethesda, Maryland.
- Trap-Neuter-Return: The wrong solution to a tragic problem", American Bird Conservancy, accessed June 23, 2014.
- "Free-Roaming Cats: A Conservation Crisis", American Bird Conservancy, accessed June 24, 2014.
- "That Cuddly Kitty Is Deadlier Than You Think", Natalie Angier, New York Times, January 29, 2013
- "The impact of free-ranging domestic cats on wildlife of the United States", Loss et al., Nature Communications 4, article 1396, 29 January 2013.
- "What to do about unwanted cats in your yard", American Bird Conservancy, accessed June 23, 2014.
- Raasch, Chuck (October 3, 2012). "Free-roaming cats stir emotional debate on bird safety". USA Today.
'I detest the killing of cats and dogs or anything else,' says George Fenwick, president of the American Bird Conservancy. 'But this is out of control, and there may be no other answer.'
- "Final Position Statement: Feral and Free-Ranging Domestic Cats", The Wildlife Society, "Approved by Council August 2011. Expires August 2016".
- "Setting the Record Straight", Alley Cat Allies, accessed Sept. 23, 2014, links to fact sheets and articles critiquing several studies. One is Gregory J. Matthews' critique of the Scott R. Loss et al. January 2013 article in Nature Communications from which the 1.4 million to 3.7 billion bird deaths estimate now in use arose: "A review of the statistical methods employed in the article 'The impact of free-ranging domestic cats on wildlife of the United States'", Feb. 4, 2013. Some of his comments were that the article was filled with "numerous major ﬂaws in the statistical arguments made" that made it "unacceptable for publication"; it was unclear how predation rates were obtained, and then "applying these estimates to all cats across the country is highly questionable"; and extrapolation was wrong: "Based on a small sample of cats over three summer months in one speciﬁc geographic area, the authors see ﬁt to extrapolate this predation rate to all cats at all times of the year in all geographic regions in the United States."
- "Biology and Behavior of the Cat", Alley Cat Allies, has many links, includes "Understanding Ecosystems: Why Removing Cats is Worse for Everyone" which covers a variety of topics. See also this link for one example of possible benefits of feral cats to endangered wildlife: "Feral cats help some endangered mammals survive, report says", Gabriel Popkin, The Sydney Morning Herald, August 29, 2013.
- "Feral or very fearful community cats have historically been euthanized either immediately or at the end of a holding period at most shelters." "Feline Shelter Intake Reduction Program FAQs: What happens to community cats in animal shelters?", Kate Hurley and Julie Levy, Maddie's Institute, January 2013.
- "TNR saves taxpayers money by reducing free-roaming cat populations which in most cases end up in municipal shelters and have to be euthanized", "Community/Feral Cats: Trap/Neuter/Return: What it is and why it works", Best Friends Utah, accessed June 24, 2014; see also "Free to Roam: A Small City's New Policy that Saves Feline Lives and Tax Payer Money", Maddie's Institute, May 2013. For savings involved in implementing TNR combined with other measures of no kill animal sheltering, see "Dollars and Sense: The Economic Benefits of No Kill Animal Control", The No Kill Advocacy Center.
- "Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population", Julie K. Levy et al., JAVMA, Vol. 222, No. 1, January 1, 2003, pp. 42–46.
- For a detailed response to a critique of TNR, see Peter J. Wolf, Vox Felina, 2010, "Reassessment: A Closer Look at 'Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return'".[self-published source?]
- "Trap-Neuter-Return Effectively Stabilizes and Reduces Feral Cat Populations", Alley Cat Allies. Case studies of TNR programs from Chicago to San Francisco to Rome, Italy. Some colonies reduced to zero residents when the last remaining feral cat died (Washington, D.C. at age 17, Newburyport, MA at age 16).
- "Are cats causing bird declines?" The Royal Society for the Protection of Birds, accessed June 23, 2014.
- for example, Joe Vaccarelli, "Denver Animal Shelter partners up to help reduce feral cat population", The Denver Post, June 12, 2014
- Ellen Perry Berkeley, "TNR: Past, Present and Future: A History of the Trap-Neuter-Return Movement" (Washington: Alley Cat Allies, 2004), p. 1
- for example, Humane Society of Tampa Bay, "TRAP / NEUTER / VACCINATE / RETURN (TNVR): What is TNVR?", accessed June 15, 2014. Note that at this link, the organization also used the term TNR to refer to the program: "In December 2011, Hillsborough County Commissioners passed a resolution recognizing Trap-Neuter-Return to better control community cat populations." and adding a link to a Youtube video, "Why TNR is better than trap and kill."
- Society for the Prevention of Cruelty to Animals, Montreal, Quebec, "Do you know about our TNRM program?", July 5, 2013, accessed June 15, 2014
- for example, National Pet Alliance "NPA's TTVAR Program: Trap, Test, Vaccinate, Alter and Release", accessed June 15, 2014.
- Ellen Perry Berkeley, TNR: Past, Present and Future: A History of the Trap-Neuter-Return Movement (2004: Alley Cat Allies), ISBN 0-9705194-2-7.
- "About Us: History", Celia Hammond Animal Trust, accessed Sept. 22, 2014.
- "About the Cat Action Trust", Cat Action Trust, accessed Sept. 22, 2014.
- Roger Tabor, The Wild Life of the Domestic Cat (1983: Arrow Books), ISBN 0-09-931210-7.
- "About us: Our work with feral cats", Celia Hammond Animal Trust, accessed Sept. 22, 2014.
- "Wildcat Haven C.I.C".
- "Herald Scotland: Haven to save the wildcat from total extinction"
- Jenny Remfry, Feral Cats in the United Kingdom (JAVMA Vol. 208, No. 4, Feb. 15, 1996, pp. 520–523), at p. 522, available online at pp. 24–27 of "AVMA Animal Welfare Forum: The welfare of cats", Nov. 3, 1995.
- "Management of feral domestic cats in the urban environment of Rome (Italy)", Eugenia Natoli et al., Preventive Veterinary Medicine (2006), doi:10.1016/j.prevetmed.2006.06.005
- "History", Alley Cat Rescue Inc., accessed August 19, 2014.
- "About us", Friends of the Cat, accessed Sept. 22, 2014.
- "African wildcats", Alley Cat Rescue, Inc., accessed August 19, 2014.
- "Declaration of Rights of the Free-living Cat (translation)", École du Chat, accessed Oct. 30, 2014.
- "History of École du chat (translation)", École du Chat, accessed Oct. 30, 2014.
- "Trap Neuter Return of Feral Cats, the Responsible Solution", Steve Dale, The Internet Home of Steve Dale, accessed Sept. 23, 2014.
- AnnaBelle Washburn, The Guiding Spirit of TNR", Alley Cat Action, Fall 2001, p. 3.
- "Feral Cats: An Overview", Margaret R. Slater and Stephanie Shain (2005), in D.J. Salem & A.N. Rowan (Eds.), The state of the Animals III: 2005 (pp. 43–53). Washington, D.C.: Humane Society Press.
- "About Feline Friends Network", Feline Friends Network (originally named the Stanford Cat Network), accessed August 17, 2014.
- "Farewell to a Founder", Alley Cat Action, Summer 2001, p. 2.
- "Our History - Alley Cat Allies". Alleycat.org. 2013-12-09. Retrieved 2014-02-25.
- "Alley Cat Allies' Feral Friends Network", Alley Cat Allies, accessed Sept. 22, 2014.
- "About Us", Alley Cat Allies, accessed Sept. 22, 2014.
- "Feral Cat Coalition Video: 'Friends of the Friendless'", Feral Cat Coalition, November 2009.
- "Friend of Ferals", Maddie's Fund, 2001.
- "Welcome to Operation Catnip!", Operation Catnip, Raleigh, NC, accessed Sept. 22, 2014.
- Operation Catnip, College of Veterinary Medicine, University of Florida, accessed Sept. 22, 2014.
- "Maddie's Fund 2000–2001 annual report".
- Nathan Winograd (2009). Redemption: The Myth of Pet Overpopulation and the No Kill Revolution in America. Almaden Books, 2nd edition. ISBN 978-0-9790743-1-8.
- "Preventing Litters Tackles Pet Overpopulation at the Source", PetSmart Charities, accessed Sept. 22, 2014.
- "World Spay Day", Doris Day Animal Foundation, accessed July 21, 2014.
- "World Spay Day", Humane Society of the United States, accessed July 21, 2014.
- "About the Doris Day Animal League", Doris Day Animal League, accessed July 21, 2014.
- "70,000 Cats Helped!", Feral Cat Coalition of Oregon, accessed Sept. 22, 2014.
- Project Catsnip Leadership Palm Beach County https://projectcatsnip.org/2015/02/13/project-catsnip-printed-matierals/
- "About National Feral Cat Day", Alley Cat Allies, accessed July 21, 2014.
- "Who is Nathan Winograd?: The Middle Years", Nathan J. Winograd, February 15, 2013.
- "Q & A with Nathan Winograd", PAWS Chicago, accessed Sept. 6, 2014.
- "No Kill 101: A Primer on No Kill Animal Control Sheltering For Public Officials", No Kill Advocacy Center, accessed September 2, 2014.
- "When is No Kill Truly No Kill?", Nathan Winograd, PAWS Chicago, accessed Sept. 6, 2014.
- "Program gives feral cats shot at freedom: More than 1,200 strays have been spayed or neutered - and saved from euthanasia.", Tia Mitchell, The Florida Times-Union, Nov. 20, 2008.
- "Save Lives With Feral Freedom: A Guide to the Feral Freedom Program", Best Friends Animal Society, accessed July 11, 2014.
- "Model Programs", Best Friends Animal Society, accessed Sept. 30, 2014.
- "The breakthrough idea of the decade", Gregory Castle, The Best Friends Blog, Best Friends Animal Society, June 28, 2013.
- In Salt Lake City, an impounded feral cat is held for the mandatory holding period; then sterilized, ear-tipped, vaccinated, and released near the original location where the cat was found. "Chapter 8.11 Feral Cats", Salt Lake City, Utah: City Code, Serling Codifiers Inc., accessed Sept. 27, 2014. Working with Best Friends Animal Society, Salt Lake County Animal Services officials work to find caretakers for feral cat colonies: "Officials seek caretakers for feral cat colonies in Salt Lake County", Mark Green et al., Fox 13 News, Dec. 15, 2013.
- "City shelter wins $700k grant to save cats", Amy Worden, The Inquirer, August 25, 2014.
- "First Coast No More Homeless Pets Annual Report 10.01.12-9.30.13", at p. 9.
- "HSUS Position Statement: Trap-Neuter-Return (TNR) Humane Society of United States, March 20, 2006.
- "Conservation Overview: Free-Roaming Cats: A Conservation Crisis", American Bird Conservancy, accessed Sept. 23, 2014.
- "Trap-Neuter-Return Ordinances and Policies in the United States: The Future of Animal Control", Elizabeth Holtz, Alley Cat Allies, January 2013, pages 4 and 11.
- "On October 4, World animal day, GAWF/Animal Action will launch a mass neutering drive for the stray cats of Athens.", Greek Animal Welfare Fund/Animal Action Greece Facebook update, Sept. 18, 2014.
- "Ranks dwindling at cat sanctuary on Parliament Hill", CBC News, Dec. 2, 2012.
- Klaus J. Gerken, "A Brief History of the Cats of Parliament Hill", The Cats of Parliament Hill Blog, accessed Sept. 23, 2014.
- "The Cats of Parliament Hill Blog 2005/2006", Klaus Gerken, Dec. 9, 2005.
- "Parliament Hill's cat sanctuary 'disbands' after more than fifty years", Robert Sibley, National Post, January 5, 2013.
- "History", Richmond Animal Protection Society, accessed Sept. 23, 2014.
- "RAPS, a true no kill shelter", Carol Reichert, Pet Connection, Nov. 17, 2013.
- "Richmond Cat Sanctuary", Vancouver Foundation, 2005.
- "Vancouver Orphan Kitten Rescue Association tames the region's feral cat colonies", Stephen Hui, straight.com, April 14, 2014.
- "About us", Vancouver Orphan Kitten Rescue Association, accessed Sept. 23, 2014.
- "About us", Pierre's Alley Cat Society, accessed Sept. 23, 2014.
- "SPCA hopes new clinic will solve Halifax's feral cat issue", CTV Atlantic, March 19, 2013.
- "History of the SPCA", SPCA (Hong Kong), accessed August 16, 2014.
- "CCCP: Benefits and Challenges", SPCA(HK), accessed August 16, 2014.
- "How to Help Feral Cats: A step-by-step guide to Trap-Neuter-Return", Alley Cat Allies, 2009, updated 2002, accessed June 19, 2014.
- "Community Relations Resource Center", Alley Cat Allies, accessed July 10, 2014
- Bryan Kortis et al., Neighbourhood Cats TNR Handbook: The Guide to Trap-Neuter-Return for the Feral Cat Caretaker, Neighbourhood Cats, 2nd. edition, 2013.
- "How to Find Homes for Stray Cats: 1 Try to find the cat's home", Alley Cat Allies, accessed July 11, 2014. In Canada, consider "Helping Lost Pets: A Free National Pet Registry", database based in Ontario, and "Petsearchers Canada", service based in British Columbia.
- "Tips for Successful Trapping of Trap-Shy Cats", Alley Cat Allies, accessed July 10, 2014.
- "Socializing Feral Kittens", Alley Cat Allies, accessed July 11, 2014; and "Taming Ferals1", Urban Cat League, New York City, accessed July 11, 2014.
- "Kittens get second chance with surrogate mamas", Vincent T. Davis, MySA, April 23, 2013.
- "Fosters are desperately needed for the following types of cats and kittens", MCA Society, Conroe, Texas, accessed July 10, 2014; nursing mother cats are taken out of the shelter into foster care right away to prevent upper respiratory infection (URI).
- "Protocols: Early-Age Spay and Neuter", Alley Cat Allies, accessed July 10, 2014.
- "Feral Cat Veterinary Protocol", Alley Cat Allies, accessed July 11, 2014.
- "Spay and Neuter Clinic Information", Alley Cat Allies, accessed July 11, 2014.
- "Protocols: Eartipping", Alley Cat Allies, accessed July 11, 2014.
- "Rabies: A Public Health Victory", Alley Cat Allies, accessed July l1, 2014.
- "Distemper and Respiratory Virus Vaccines (FVRCP) Protocol for Feral Cats", Alley Cat Allies, Christine Wilford, "Are Vaccines Worth It?", 2009.
- "The Difference between Euthanasia and Killing", Alley Cat Allies, accessed July 11, 2014.
- "Post-Surgery", Alley Cat Allies, accessed July 11, 2014.
- For an example see "A Toronto Rescue Story: Hermione", Youtube user catnip42007, uploaded April 27, 2014.
- "Community lends a hand to help feral cat in Innisfil", Miriam King, The Barrie Examiner, April 22, 2014.
- "Safe Relocation of Feral Cats", Alley Cat Allies, accessed July 11, 2014.
- "Socialized Cat Guide", Alley Cat Allies, accessed July 11, 2014.
- "Colony Care Guide", Alley Cat Allies, accessed July 11, 2014.
- "Protocols: Testing - Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV)", Alley Cat Allies, accessed July 11, 2014.
- "TNR Ordinances". Neighbourhood Cats. Retrieved August 3, 2014.
- "Trap-Neuter-Return Ordinances and Policies in the United States: The Future of Animal Control", Elizabeth Holtz, Alley Cat Allies, January 2013, p. 6.
- "A Model Feral Cat Policy", No Kill Advocacy Center, No Kill Sheltering, November/December 2006.
- Urban Wildlands Group v. The City of Los Angeles, Court of Appeals of California, NO. B222696.
- "Get the Facts about the Los Angeles Trap-Neuter-Return Ruling", Alley Cat Allies, accessed August 2, 2014.
- "Va. justices rule against Henrico on feral cats", Richmond Times-Dispatch, Aug. 24, 2013, updated August 25, 2013.
- "Biloxi woman's sentence in feral cats case draws national attention", Robin Fitzgerald, Biloxi Sun-Herald, December 12, 2012.
- "Alley Cat Allies Criticizes Biloxi Judge for Misguided Punishment of Feral Cat Caregiver", Alley Cat Allies, accessed August 3, 2014.
- "Feral cat case dropped against Vandercook Lake woman under plan to trap and remove cats from neighbourhood", Brad Flory, mlive, Nov. 16, 2011.
- "Ex-National Zoo employee sentenced in attempted feral cat poisoning", Carol Cratty, CNN, December 15, 2011.
- "Kill the Cat That Kills the Birds?", Bruce Barcott, The New York times, Dec. 2, 2007.
- Phillips, Allie (2013). "The Hierarchy of Anti-Cruelty Laws: Prosecuting the Abuse of Stray and Feral Cats" (PDF). Tales of Justice. 3 (3): 1–5.
- "The Trap, Neuter, Return Program for Feral Cats", City of Toronto, accessed August 3, 2014; and "Toronto Municipal Code, Chapter 349, Animals", City of Toronto, June 13, 2013.
- "Spay, Neuter and Vet Services", City of Toronto, accessed August 03, 2014.
- "The Trap, Neuter, Return Program and the Feral Cat Coalition", City of Toronto, accessed August 3, 2014.
- "Merritt, B.C., overrun by stray cats: Bylaw officers ask RCMP to consider mischief charges against animal feeders", CBC News, Jan. 11, 2012.
- "City's approach to feral cats not effective", Joni Hughes, letter to Merritt Herald, January 12, 2012.
- "Merritt storefront clear of stray cats", Phillip Woolgar, Merritt Herald, August 7, 2012.
- "Cruelty to Animals", Criminal Code, s. 445.1.
- "Cattle and Other Animals", Criminal Code, s. 445.
- "Assaults", Criminal Code, s. 264.1(1)(c).
- "A Report on Animal Welfare Law in Canada", Alberta Farm Animal Care, June 2004.
- Natoli, Eugenia; Maragliano, Laura; Cariola, Giuseppe; Faini, Anna; Bonanni, Roberto; Cafazzo, Simona; Fantini, Claudio (2006). "Management of feral domestic cats in the urban environment of Rome (Italy)". Preventive Veterinary Medicine. 77 (3–4): 180–5. doi:10.1016/j.prevetmed.2006.06.005. PMID 17034887.
- "Analysis of the impact of trap-neuter-return programs on populations of feral cats", Patrick Foley et al., JAVMA, Vol 227, No. 11, December 1, 2005, p. 1775-1881.
- "Parliament Hill's cat sanctuary 'disbands' after more than fifty years". National Post. Retrieved 2013-01-05.
- "Analyzing approaches to feral cat management — one size does not fit all", Michael K. Stauskopf et al., JAVMA, Vol 225, No. 9, November 1, 2004, pp. 1361-1364.
- Castillo D, Clarke AL (2003). "Trap/neuter/release methods ineffective in controlling domestic cat 'colonies' on public lands" (PDF). Natural Areas Journal. 23 (3): 247–53.
- "Humane strategies for controlling feral cat populations", Julie K. Levy et al., JAVMA, Vol 225, No. 9, November 1, 2004, pp. 1354-1360, at p. 1356.
- "County of Santa Clara Animal Care & Control Places 100% of Healthy Dogs and Cats in 2011", County of Santa Clara, January 25, 2012, p. 2.
- Kathy L. Hughes et al., "The Effects of Implementing a Feral Cat Spay/Neuter Program in a Florida County Animal Control Service", Journal of Applied Animal Welfare Science (2002), 5(4), pp. 285-298.
- "Trap, neuter, return program saving lives of stray cats", Vic Rickaert, Indystar, Sept. 24, 2014.
- "Why Trap-Neuter-Return Feral Cats: The Case for TNR", Alley Cat Allies, accessed July 16, 2014.
- Kraft, W (1998). "Geriatrics in canine and feline internal medicine". European journal of medical research. 3 (1–2): 31–41. PMID 9512965.
- "State of Pet Health 2013 Report", Banfield Pet Hospital.
- "Body Condition of Feral Cats and the Effect of Neutering", Karen C. Scott et al., Journal of Applied Animal Welfare Science (2002), 5(3), pp. 203–213, at p. 212.
- "Implementation of a Feral Cat Management Program on a University Campus", Kathy L. Hughes et al., Journal of Applied Animal Welfare Science, 5(1), 2002, pp. 15-28.
- Dollars & Sense: The Economic Benefits of No Kill Animal Control: A Guide for Public Officials", No Kill Advocacy Center, accessed Sept. 6, 2014.
- "Port Orange expanding feral cat program", Ray Weiss, The Daytona Beach News-Journal, May 7, 2013.
- "U.S. Public Opinion on Humane Treatment of Stray Cats", Karyen Chu et al., Alley Cat Allies, 2007.
- "Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return", Travis Longcore et al., Conservation Biology (2009), Vol. 23, No. 4, pp. 887-894.
- "In the UK, the vast majority of pet cats have free access to the outside world, or are at least allowed to go outside unsupervised for large parts of the day." "A world of difference - How cat ownership in America differs to the UK", Pets4Homes, accessed September 1, 2014.
- Roger Tabor, Understanding Cat Behavior (2003: David & Charles Ltd.), ISBN 978-0-7153-1589-7.
- "Sorry, Cat Lovers: Trap-Neuter-Return Simply Doesn't Work", Richard Conniff, TakePart Webpage, April 1, 2013, accessed Jan 03, 2015.
- Berkeley, Ellen Perry, "TNR: Past, Present and Future: A History of the Trap-Neuter-Return Movement" (2004: Alley Cat Allies), ISBN 0-9705194-2-7.
- Anderson, Laurie Halse, "Vet Volunteers: Homeless" (2007: Puffin Books), ISBN 978-0-14-240863-6. Children, fiction.
- Laidlaw, Rob, "Cat Champions: Caring for our Feline Friends" (2013: Pajama Press), ISBN 978-1-927485-54-5 (paperback); ISBN 978-1-927485-31-6 (bound). Youth, non-fiction.
- Lee, Ingrid, "Cat Found" (2011: Chicken House, New York), ISBN 978-0-545-31770-2. First published in the UK as "Dustbin Cat" in 2010; ISBN 978-1-906427-53-5. Children, fiction.
- MacLean, Jill, "The Nine Lives of Travis Keating" (2008, Fitzhenry & Whitside), ISBN 978-1-55455-153-8. Youth, fiction.
- "Humane Cat Population Management Guidance" - report of International Companion Animal Management Coalition to help governments worldwide address community cat populations in a humane manner, includes TNR.
- "Alley Cat Allies" - Website offers vast array of links and publications with practical information about TNR and community cats; for veterinarians, shelters and community members.
- "How to Help Feral Cats: A step-by-step guide to Trap-Neuter-Return" - Many practical tips on TNR, prepared by Alley Cat Allies in 2009 and updated in 2002.
- "Cats & the Environment Resource Centre" - Science of cats and wildlife (especially birds), setting the record straight, links to resources provided by Alley Cat Allies.
- "Neighborhood Cats" - TNR organization in New York city, provides many resources online and otherwise about TNR and community cats: news updates, tools, webinars, videos, legal info: "Model TNR Ordinances now available from Neighborhood Cats"; TNR handbook (link below).
- "Neighborhood Cats TNR Handbook: The Guide to Trap-Neuter-Return for the Feral Cat Caretaker" - Bryan Kortis et al., Neighborhood Cats, 2nd edition, 2013. Comprehensive guide to TNR, 162 pages. OK to print/distribute except in New York city, where copyright requires getting copies from Neighbourhood Cats.
- "Feline Shelter Intake Reduction Program FAQs" - Maddie's Institute, January 2013 article on community cats. Other articles on feral cats: "Feral/Community Cats Articles". Organization based in Pleasanton, California, supports research on helping feral cats and shelter animals, and provides funding for TNR and spay/neuter programs.
- "What You Can Do To Help Feral Cats", Humane Society of the United States, July 3, 2013, accessed June 20, 2014. Resources for individuals, organizations and public officials.
- "Feral Cats FAQ", ASPCA, accessed June 20, 2014. Extensive resources, answering questions from what is a feral cat, to how can I keep feral cats out of my yard, to how can I become a colony caretaker, and more.
- "Vox Felina", blog "Providing critical analysis of claims made in the name of science by those opposed to feral/free-roaming cats and trap-neuter-return"
- Trap Neuter Return, TNR information from Stray Cat Alliance, organization based in Los Angeles, California.
- "Alley Cat Rescue" Some links on feral cats and TNR topics from organization based in Mount Ranier, Maryland.
- "What is Trap-Neuter-Return" - Animal Coalition of Tampa's Project Spay Day.
- ca-r-ma.org, a Canadian organization fostering TNR via a system of community based affiliated groups throughout the Maritime Provinces.
- What is Trap-Neuter-Return (TNR)? - TNR info by Forgotten Cats, Inc., of Greenville, Delaware.
- Information on Managed Cat Colonies and TNR - criticism of TNR by American Bird Conservancy.
- "Wildcat Haven" - Project successfully using TNR to conserve the Scottish wildcat from hybridisation with feral cats.