This article needs to be updated. In particular: Dogs need to be integrated into the beginning of the article since they are included in the later parts..April 2019)(
Trap–neuter–return or Trap–neuter–release, commonly known as TNR, is a method for attempting to humanely and effectively manage free-roaming domestic cats. The process involves live-trapping the cats, having them spayed or neutered (aka: desexed), ear-tipped for identification and, if possible, vaccinated, then releasing them back into their territory. If the location is deemed unsafe or otherwise inappropriate, the cats may be relocated to other appropriate areas (barn/farmyard homes are often considered ideal) Ideally, friendly adults and kittens young enough to be easily socialized are retained and placed for adoption. Feral cats cannot be socialized, shun most human interaction and do not fare well in confinement, so they should not be retained. Cats suffering from severe medical problems such as terminal, contagious, or untreatable illnesses or injuries, are often euthanized.
In the past, the main goal of most TNR programs was the reduction or eventual elimination of free-roaming cat populations. It is still the most widely implemented non-lethal method of managing them. While that is still a primary goal of many efforts, other programs and initiatives may be aimed more towards:
- providing a better quality of life for community cats
- stemming the population expansion that is a direct result of breeding.
- improving the communities in which these cats are found
- reducing "kill" rates at shelters that accept captured free-roaming cats, in turn improving public perceptions and possibly reducing costs
- eliminating or reducing nuisance behaviors to decrease public complaints about free-roaming cats
The earliest documented practice of trap–neuter–return was in the 1950s, led by animal activist Ruth Plant in the United Kingdom.
TNR usually stands for trap–neuter–return. It is sometimes described as trap–neuter–release. The word "return" emphasizes that most feral cats are returned to their original locations under such a program. Variant acronyms and terms include: TNSR (for trap–neuter/spay–return), TNVR (trap–neuter–vaccinate–return), TNRM (trap–neuter–release–maintain or manage) where "maintain" generally means caregivers feed and monitor the feral cats after they are returned to their territories, and TTVAR (trap–test–vaccinate–alter–release).
TVHR (trap–vasectomize/hysterectomize–release) refers to a different method of cat population management, despite its similar name. TVHR differs in the type of sterilization surgery performed on the cats. Unlike traditional spays (ovariohysterectomy) and neuters (castration) which are done in TNR, the vasectomies and hysterectomies in TVHR result in sterile but sexually active cats.
RTF (return to field) or TNS (trap, neuter, shelter return) are alternative approaches that simply focus on the trap and desex portion and do not include a colony management aspect. In some instances, a receiving shelter will return a cat to where it was found; in other cases shelters are completely bypassed - a person takes a free-roaming live-trapped cat in for desexing, than returns it to where it was found.
Advocacy and oppositionEdit
TNR as a method of managing free-roaming cat populations is a very controversial topic. Global attitudes towards these cats vary from those who see them as pets to those who see them as infestations which need to be eliminated. Many international, national, and regional organizations and association, both professional and advocacy-based, have publicly aligned themselves into 3 basic groups: those that stridently oppose managing, maintaining, or tolerating free-roaming cats and hence TNR; those who conditionally support TNR as a part of a community cat management program (which includes community cat oversight and monitoring); and those who unconditionally support and endorse TNR.
Some well-known organization positions that support or conditional support TNR include:
- The American Society for the Prevention of Cruelty to Animals: "The ASPCA endorses Trap-Neuter-Return (TNR) as the only proven humane and effective method to manage community cat colonies." It clarifies its position by stating that managing "involves a colony caretaker who provides food and adequate shelter and monitors the cats' health."
- The Humane Society of the United States (HSUS): "we support Trap-Neuter-Return (TNR) and similar sterilization programs, legislation that allows for and supports non-lethal population control, and coalition-based approaches that involve community leaders, citizens, and stakeholders to implement effective community cat management programs." They further clarify this view by stating: "The HSUS believes that the humane reduction and eventual elimination of unowned cat populations should be the end goal for all TNR participants and supporters. TNR should be considered a humane means to an end, not a method of permanently maintaining outdoor cat populations.
- The American Humane Association: "In some situations, safe cat colonies can be maintained by caretakers. American Humane Association supports trap, neuter and release programs for colony cats – especially for feral cats. Whenever possible, homes should be found for colony cats that might be successfully socialized."
- The UK's Royal Society for the Prevention of Cruelty to Animals (RSPCA): For feral cats "supports Trap, Neuter and Release (TNR) programmes with veterinary support. Healthy cats should be neutered, ear-tipped and returned or, where appropriate, re-sited."
Many of the numerous international, national, and regional organizations that oppose TNR or free-roaming cat colony management are involved in wildlife care and conservation, birding, ecology conservation, and environment preservation. Some of these, include:
- The International Wildlife Resource Center: "The IWRC supports the humane removal of feral cat and dog populations, including feral cat colonies, through the rehabilitation and adoption of suitable animals into domestic environments and humane euthanasia of animals that cannot be rehabilitated and re-homed." They point out that, as domestic animals "subsidized" by people, they exceed the ability for the environment to support them without resulting in damage to wildlife.
- The Wildlife Society: "TNR undermines the work of wildlife professionals and severely jeopardizes the integrity of native biodiversity."
- The American Bird Conservancy (ABC): "Cats have been introduced into new habitats across the globe with terrible results. Outdoors, cats are a non-native and invasive species that threaten birds and other wildlife, disrupt ecosystems, and spread diseases." They advocate responsible pet ownership and "oppose Trap, Neuter, Release (TNR) for feral cats because of the persistent and severe threats posed by feral cat colonies."
Advantages and disadvantagesEdit
Various studies and arguments have been presented both in support of and in opposition to free-roaming cats and TNR.
Reduced population over timeEdit
Some long-term studies have claimed or been cited to show that TNR is effective in stopping reproduction and reducing the population over time, but the methodology, analysis and conclusions of some of these studies have been called into question.
- 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. However, as many proponents fail to note,TNR was not the sole reason for success. The population reduction was primarily from adoption (47%) and euthanasia (11%), or due to the cats no longer living on site with their whereabouts unknown (15%).
- A TNR program begun in 1992 by the Merrimack River Feline Rescue Society (MRFRS) on the central waterfront of Newburyport, Massachusetts has been widely cited as an example of TNR success on a community level; however, only superficial reports about what took place have been available and there is very little statistical data to support the claims.
The success of specific focused studies to advocate TNR as a solution for controlling and reducing free-roaming cat populations worldwide is problematic. More broad-based approaches include using matrix population models to estimate the efficacy of euthanasia versus trap-neuter-return for management of free-roaming cats, such as the one researchers established for use in urban environments.
Efforts to assess the effectiveness have been hampered by the lack of sufficient monitoring data. Having some professional assistance, adapting the population monitoring framework developed over decades by wildlife biologists, and systematic monitoring can evolve into a relatively low-cost, high-value adjunct to ongoing management efforts.
The potential problem of TNR advocacy and increased public awareness of non-lethal intervention actually contributing to the increasing numbers of free-roaming pets, by enabling pet owners to make conscious decisions to illegal dump or abandon their animal without having to worry about lethal control measures, has been a contentious point. In a widely cited example of cat control by relocation (cats from Bidwell Park, CA, were trapped and moved to a private sanctuary), the high visibility of the project encouraged more abandonment. In another study, to explain the ingression of cats it was found that "the high quality and visibility of the program ... may have encouraged abandonment of cats if owners believed that the cats would be well taken care of after abandonment. Abandonment may also have occurred if owners believed that cats would be better off under the care of the program rather than surrendered to a shelter where they would face the risk of euthanasia." Some of that cats that came in to the TNR colony has already been sterilized, some of these had ear-tips and some did not.
Introgression, particularly of intact cats, has been noted to be a barrier to decreasing cat populations over time through TNR efforts. It has become apparent that the while the TNR process can reduce or limit the growth rate of the colony through reproduction, it may not reduce the population numbers if it is the sole method of intervention. Population reduction occurs primarily through adoptions of non-feral cats, natural death or euthanasia of sick animals, and disappearance or emigration of cats. TNR works together with these factors to reduce reproduction and thus to minimize replacement of animals lost from the colony. Other factors such as immigration of cats from surrounding areas can counteract its effect. Thus, the impact of TNR interventions on unowned cat populations can be complex, and ongoing management of colonies becomes an important component in optimizing reductions in the cat population.
It is important to note that the potential for TNR to decrease free-roaming cat populations has only been noted in fully managed colonies (monitored with active involvement and interventions by colony managers). Current trends towards unmanaged TNR, RTF, and/or TNS disregard the "managed" portion and, as such, cannot be cited as effective measures towards that goal.
The "kill" or "no-kill" debate (euthanasia)Edit
TNR is often presented to public officials and policymakers as a viable alternative to lethal methods with several benefits.
- Reducing euthanasia numbers.
- It has been claimed that euthanasia in shelters is the leading cause of death of cats. Proponents of TNR use this "kill" statistic to promote "no-kill" tactics. However, in the USA there is no exact numbers of animals being euthanized each year. Only a few states require animal shelters to keep records about animals being euthanized , and there is no agency responsible for collecting or verifying this data. The American Society for the Prevention of Cruelty to Animals (ASPCA) has noted a marked decrease in euthanasia rates since 2011 and Humane Society of the United States reported that euthanasia of animals in shelters has been declining sharply since 1970. In addition, the reasons for euthanasia vary. Animals may be euthanized because of shelter over-crowding, for medical reasons (illness or injury), for court-mandated reasons, or because of financial/staff limitations.
- When the number of animals coming into a shelter exceeds its ability to care for, hold, or find foster placements, the facility may end up euthanizing animals. This could include even adoptable kittens or cats simply because they cannot be taken care of. A not atypical outcome for a cat judged to be "feral" after being taken to a traditional shelter not practicing no-kill sheltering is euthanasia (humanely putting the animal to death). "Feral" cats do not tolerate being caged or handled and many shelters are unable to manage them without putting the animal or the staff at risk. TNR could alleviate this.
- Facilities have reported notable decreases in intakes and euthanasia since implementing TNR programs. It is not clear, however, if these decreases can be directly attributed to TNR, or to concurrent efforts to increase and implement owned pet spay-neuter programs, new initiatives of adoption campaigns where animals at risk of "kill" are transported to areas where animals for adoptions are needed, or public awareness campaigns to enhance adoption rates.
- Cost savings
- Proponents of TNR claim that while neutering cats may be costly, euthanizing them costs more. However, the cost savings associated with TNR are location-specific and accurate estimates involve taking into account numerous variables including volunteer support, donations, grants, and local spay-neuter agreements for low-cost services. Cost savings fluctuate based on the type of TNR program implemented, the extent of animal control involvement, the volunteer base available, and the community's overall support of TNR. Over time, through attrition and sterilization efforts, if the free-roaming population declines savings may be realized by total decreased expenditures on them.
- In a 10-year study in Orange County, Florida, after a feral cat sterilization program was instituted in which 7,903 feral cats neutered, the cost was an estimated $442,568, as compared to $1,098,517 if they had been impounded and euthanized.
- 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 theoretical savings of $123,000 was projected based on not having to impound the offspring that the cats may have produced if not spayed.
- Improved morale and public support
- A 2011 survey of U.S. pet owners found that 71% agreed that “Animal shelters should only be allowed to euthanize animals when they are too sick to be treated or too aggressive to be adopted,” while only 25% agreed that “Sometimes animal shelters should be allowed to euthanize animals as a necessary way of controlling the population of animals.”
- In 2019, a study was published that concluded "for most Brisbane City (Australia) residents, when awareness is raised about the problem of urban stray cats and management strategies, the majority are supportive of a TNR community program with little or no persuasion required."
- TNR programs may have a side effect of reducing the stress and strain volunteers and staff have related to euthanasia in shelters. A 2019 study concluded that euthanasia‐related strain is prevalent among shelter employees. It's associated with increased levels of general job stress, work‐to‐family conflict, somatic complaints, and substance use; and with lower levels of job satisfaction.
Improving the cats' health and welfareEdit
It has been claimed that TNR programs improve the welfare of free-roaming cats in many ways:
- Spayed female cats will no longer be burdened by pregnancy or nursing litters. Females have been found to be pregnant throughout the year. A study of the reproductive capacity of free-roaming cats showed they may have an average of 1.4 litters a year, with a median of 3 kittens/litter.
- Alleviating unnecessary suffering of kittens. 75% of the kittens born to free-roaming cats being studied died or disappeared before 6 months of age. Trauma was found to be the most common cause of death.
- Improved overall heath. The American Veterinary Medical Association (AVMA) notes that properly managed programs can improve quality of life through better nutrition, vaccination to prevent disease, and euthanasia of sick and debilitated cats. However, management of colonies is not a mandated practice, nor is ongoing monitoring and follow-up care once released after the neuter-spay. Vaccinations, medical examination, care, or treatments may or may not be a part of any given TNR effort.
- Fighting may decline, thus reducing injuries. A study between 4 colonies, 2 of neutered males and 2 of intact males, found that the frequency of agonistic behavior was lower in the neutered groups. However, the agonistic behavior that was noted in the neutered groups was attributable to interactions involving intact males who had moved into them. As noted above, introgression of cats is a common factor noted in studies.
Not all free-roaming cats are feral. Nor are all the cats that end up in live traps. Some are owned, but allowed to roam; some have escaped their homes or owners and are strays; some may have been abandoned or "dumped." Clearly, the "return" or "release" component of TNR is not in all of their best interests. The assessment, after trapping, of "social" (friendly & adoptable), "social but timid or scared" (may adjust and be adoptable), "not social" (not feral, prefers to not be handled, hard to adopt out) or "feral" is crucial if TNR is intended to be in the best interest of the animal. 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.
Managed TNR programs that involve continuous active intervention on detection along with treatment and prevention of some of the more common diseases and parasites may help improve their overall health.
The overall effect of TNR on the health and welfare of free-roaming cats as a whole is not possible to measure. In numerous studies, many of the cats simply disappeared, so follow-up was impossible. They are subject to injury, illness, or death from numerous things: trauma from humans or human machines or other animals, predation by wildlife, toxins and poisons, contagious diseases, exposure to harsh weather, malnutrition, infections, and parasitic debilitation.
TNR may help reduce public complaints pertaining to free-roaming cats. Female cats will ‘call’ (come into season and be receptive to the male cat) regularly, about every three weeks during sexually active times of the year if they do not get pregnant. Having un-spayed female cats in an area will attract un-neutered males with the attendant problems of spraying, fighting and caterwauling.
- After starting a TNR program in 1995, animal control in Orange County, Florida, received fewer complaints about cats, even after broadening the definition of a nuisance complaint.
- A study of a TNR program at Texas A&M University in 1998-2000 reported that the number of cat complaints received by the university's pest control service decreased from Year 1 to Year 2.
Effects on wildlife from huntingEdit
Numerous studies have shown that free-roaming cats can have a significant derogatory impact on native wildlife. They cause considerable wildlife destruction and ecosystem disruption, including the deaths of hundreds of millions of birds, small mammals, reptiles, amphibians, and fish. They have been linked to the extinction of 63 species and pose a threat to 360 more.
Cats are now thought to be the single largest cause of anthropogenic bird mortality in North America.
There have been recorded instances of species extinction caused by them on islands. In 2004, targeted eradication programs had successfully removed free-roaming domestic cats from at least 49 islands. Citing eradication of invasive mammals from islands as a proven conservation tool, with clear evidence of subsequent native species recovery, it is gaining recognition as a recommended method of sustaining native biodiversity on islands.
Free-roaming cats have been documented hunting and killing prey without eating it.
Risks to human and animal healthEdit
Stray animals in general may have significant impacts on public health due to factors such as a lack of preventive measures (e.g. vaccines, deworming), easy access to intermediate hosts (e.g. rats and birds), and unrestricted entry to public areas such as parks and playgrounds. Their presence is a major risk for the transmission of zoonotic diseases.
Free-roaming cats can act as vectors for diseases that can impact humans as well as other animals, domestic and wild. Transmissions can occur within the species and to other species. Feline leukemia virus, feline immunodeficiency virus, ectoparasites (fleas, mites, lice, ticks), intestinal and protozoan parasites, Rickettsia, and Coxiella ("Q Fever") are examples of inter and intra-species shared diseases and parasites.
There are numerous zoonotic pathogens shed in feline feces, such as Campylobacter and Salmonella spp; ascarids (e.g., Toxocara cati); hookworms (Ancylostoma spp); and the protozoan parasites Cryptosporidium spp, Giardia spp, and T gondii. Contaminated soil is an important source of infection for humans, herbivores, rodents, and birds and several studies suggest that pet feces contribute to bacterial loading of streams and coastal waters.
The triggers for a trap–neuter–return program include: a perception of free-roaming cats or kittens in need, a steadily increasing number due to open breeding, an unmanageable burden on community resources while trying to manage or eliminate the cats, and when the cats become a notable nuisance or concern.
There are many different TNR programs, protocols and processes.
Treatment by countryEdit
Domestic cats can be found on every continent except Antarctica. Control of free-roaming dogs and cats is a worldwide problem. Beyond pragmatic and scientific considerations, cultural heritage, ethical beliefs, and social and economic impacts play critical roles in efforts to address it.
The legal status of free-roaming and community cats varies from location to location, as do the histories and efforts of TNR programs. There are numerous governments supporting trap–neuter–return. The following highlights some of the TNR issues around the world:
In a Feb 17, 2017, news release in the Sydney Morning Herald, Threatened Species Commissioner Gregory Andrews reportedly summarized the reason for the federal government's intention to wipe out 2 million feral cats – about a third of the population – by saying that they are "the single biggest threat to our native animals, and have already directly driven into extinction 20 out of 30 mammals lost." This cull is planned to go until 2020.
Across Canada, municipalities are replacing old animal control bylaws with “responsible pet ownership” rules intended to direct the obligations of pet behavior to their owners. A common feature of the accelerating trend is a requirement that owners get a license for their cats and ensure they don't roam.
In January 2012, a bylaw officer in Merritt, British Columbia, removed cat food and asked the Royal Canadian Mounted Police to consider criminal charges against those feeding the community cats.  No charges were laid, but the rescue group's business license was revoked and it was forced to move from its storefront location.
The City of Toronto, Ontario, includes TNR in its animal services and has a bylaw specifically addressing TNR and managed colonies. The Toronto Animal Services offers spay and neuter for colonies that are registered and have an assigned trained caretaker.
TNR was practiced in Denmark in the mid-1970s, as reported at the 1980 Universities Federation for Animal Welfare (UFAW) symposium in London. Denmark's Society for the Protection of Cats practiced both tattooing and tipping the ear of the neutered cats to identify them.
In 1978, the city of Paris 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.
Killing feral cats has been illegal in the Lazio Region, which includes Rome, since 1988. A study in 2006 found almost 8,000 were neutered and reintroduced to their original colony from 1991 to 2000. It concluded that spay/neuter campaigns brought about a general decrease in cat numbers among registered colonies and censused cats, but the percentage of cat immigration (due to abandonment and spontaneous arrival) was around 21 percent. It suggested that TNR 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.
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 permanently removed from their colony; cat caretakers can be formally registered; and TNR methods are outlined in the national law on the management of pets.
Negative attitudes towards cats in general and free-roaming cats in particular are culturally entrenched. Cats are culled for meat, or for body parts used in concocting health aids. The 2011 South Korean amendment of its Animal Protection Law required humane methods to be used in the transportation and euthanasia of animals. Some areas have government supported TNR programs, but these programs are often scorned by the public and poorly managed. Negative attitudes and fear towards cats in general have been slow to change and free-roaming cats may be subjected to abuse or violence. In recent years, however, South Korea's attitude toward homeless cats has improved.
The Department of Conservation (DOC) is legislatively mandated to control feral cats on public conservation land. It has eradicated feral cats from several offshore islands. Control techniques include poisoning, trapping and shooting. Lethal controls follow efficient and humane best-practice techniques and adhere to the Animal Welfare Act 1999.
In 2017, the New Zealand Companion Animal Council released it's National Cat Management Strategy Discussion Paper, in which they advise that "when stray cat management is justified, non-lethal methods of removal (e.g. rehoming or best practice managed, targeted trap-neuter-return [mtTNR]) must always be the first option." This discussion recognized the limited value of mtTNR in some situations. Their goal is for all cats in New Zealand to be responsibly owned and that cats are humanely managed in a way that protects their welfare and the environment.
Turkey has a significant problem with free-roaming dogs and cats and the country is struggling with ways to manage the problem. Its Animal Protection Law prohibits killing “ownerless animals” except where permitted by the Animal Health Police Law. They are required to be taken to animal shelters established or permitted by the local authorities. In keeping with the tenents of its main religion, most Turks are very much against euthanasia of animals for “population control;” recent efforts to curb an ever-increasing population include TNR for roaming cats and dogs.
The earliest documented practice of trap–neuter–return was in the 1950s, led by animal activist Ruth Plant in the UK. In the mid-1960s, former model Celia Hammond gained publicity for her TNR work "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".
The first scientific conference on “the ecology and control of feral cats” was held in London in 1980 and its proceedings published by the Universities Federation for Animal Welfare (UFAW). Subsequent UFAW publications in 1982, 1990, and 1995 were the primary scientific references for feral-cat control for many years.
- Saving the genetically pure Scottish wildcat
- Removing all feral cats from the region
- Using humane, neutering-based feral cat controls
- Establishing buffer zones to prevent feral cats returning to the area
Currently, there is no applicable federal law that controls the feral cat issue. A few states have recently recognized the need to establish programs to control feral cat populations since their effects on wildlife have now been more widely studied and the efficacy of euthanasia for population management has been criticized. These laws vary in their approaches. The Endangered Species Act and the Migratory Bird Treaty Act, have played a role in setting forth policy on feral cats. The federal case, American Bird Conservancy v. Harvey, puts the challenge of bird advocates under these federal laws in response to cat programs front and center. The merits of this case have not been decided but have the potential to impact both sides of the issue.
In a January 2013 legal brief, Alley Cat Allies provided evidence that at least 240 municipal or county governments in the United States 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 organization Neighborhood Cats has cataloged local ordinances in 24 US states. Model ordinances are available from Neighborhood Cats, Alley Cat Allies, and the No Kill Advocacy Center.
On January 29, 2019, the Hawaii Invasive Species Council adopted a resolution supporting the keeping of pet cats indoors and the use of peer-reviewed science in pursuing humane mitigation of the impacts of feral cats on wildlife and people.
TNR of cats is illegal in Alaska.
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.
Some caretakers have been prosecuted for taking care of feral cats. The perplexing issues of where a "feral" cat fits in local ordinance depends on the consideration as to whether they are pets or wildlife and whether they are "owned" or not. Many ordinances restrict feeding of wildlife (excluding birds). Then there are ordinances that restrict how many pets a person may own, and those that disallow free-roaming pets. 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. In 2012, 78-year-old Dawn Summers was sentenced to community service for 'hoarding"; 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. The Virginia Supreme Court found a zoning ordinance too broad in 2013, 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.
Opponents of feral cats have also been prosecuted for violating animal-protection laws by trying to harm or kill the animals. In 2007, Jim Stevenson stood trial for shooting a cat from a colony in Galveston County, Texas, which he reportedly did after observing 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. In December 2011, wildlife biologist Nico Dauphiné received a suspended sentence for attempting to kill feral cats with rat poison in Washington, DC.
- Kortis, Bryan (2013). Neighborhood Cats TNR Handbook:The Guide to Trap-Neuter-Return for the Feral Cat Caretaker (2nd Edition). Susan Richmond, Meredith Weiss, Anitra Frazier, joE. Needham, Lois McClurg & Laura Gay Senk. https://www.neighborhoodcats.org/how-to-tnr/getting-started/what-is-tnr: Neighborhood Cats, Inc. ©.
- For example: "Barn Cat Program". Kitsap-Humane.org. Silverdale, Washington: Kitsap Humane Society. Retrieved June 19, 2014.
- "Trap-Neuter-Return (TNR) Program For Community Cats | Humane Society of the Pikes Peak Region". www.hsppr.org. Retrieved 2019-03-22.
- Ark, Noah's. "Feral Cat Program". Noah's Ark Animal Foundation. Retrieved 2019-03-22.
- Hughes, Kathy L.; Slater, Margaret R. (2002). "The Effects of Implementing a Feral Cat Spay/Neuter Program in a Florida County Animal Control Service". Journal of Applied Animal Welfare Science. 5 (4): 285–298. CiteSeerX 10.1.1.566.9583. doi:10.1207/S15327604JAWS0504_03. PMID 16221079.
- Perry Berkeley, Ellen (2004). TNR: Past, Present and Future: A History of the Trap–Neuter–Return Movement. Alley Cat Allies. ISBN 978-0-9705194-2-9.
- for example, Joe Vaccarelli, "Denver Animal Shelter partners up to help reduce feral cat population", The Denver Post, June 12, 2014
- "How to Help: Financial Donations", Corporation of Delta, accessed August 6, 2014. Quote: "... our Trap–Neuter/Spay–Return program for feral cats ...".
- for example, Humane Society of Tampa Bay, "Trap / Neuter / Vaccinate / Return (TNVR): What is TNVR?" Archived 2014-10-05 at the Wayback Machine, 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?" Archived 2014-10-06 at the Wayback Machine, 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.
- "Trap-Vasectomy-Hysterectomy-Return (TVHR) Is No Substitute for Trap-Neuter-Return (TNR)". Alley Cat Allies. Retrieved 2019-03-17.
- McCarthy, Robert J.; Levine, Stephen H.; Reed, J. Michael (August 15, 2013). "Estimation of effectiveness of three methods of feral cat population control by use of a simulation model". Journal of the American Veterinary Medical Association. 243 (4): 502–511. doi:10.2460/javma.243.4.502. PMID 23902443.
- Staff, DVM360.com (Sep 2013). "Tufts researchers say TNR is not most effective method to control feral cat population".
- "Million Cat Challenge | Return to Field". www.millioncatchallenge.org. Retrieved 2019-03-30.
- "The Global Impact of Feral Cats | The Ecology Global Network". Ecology Global Network. 2013-08-27. Retrieved 2019-03-18.
- "Feral Cats FAQ", ASPCA, second paragraph, accessed June 20, 2014. Resources provided here on TNR and feral cats.
- "Our position on cats". The Humane Society of the United States. Retrieved 2019-03-18.
- "Animal Welfare Policy & Position Statements". Aug 2012.
- "RSPCA policies on animal welfare". 2014.
- "IWRC Education and Resources for Wildlife Conservation Worldwide: Feral Cats and Dogs Position Statement" (PDF). Sep 2014.
- "Effects of an Invasive Species: Domestic Cats" (PDF). Mar 2017.
- "Cats Indoors". American Bird Conservancy. Retrieved 2019-03-22.
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