Trap–neuter–return (TNR), also known as trap–neuter–release, is a controversial method that attempts to manage populations of feral cats. The process involves live-trapping the cats, having them neutered, ear-tipped for identification, and, if possible, vaccinated, then releasing them back into the outdoors. If the location is deemed unsafe or otherwise inappropriate, the cats may be relocated to other appropriate areas (barn/farmyard homes are often considered best). Often, 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 are not 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 feral 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, and eliminating or reducing nuisance behaviors to decrease public complaints about free-roaming cats. Scientific research has not found TNR to be an effective means of controlling the feral cat population. Literature reviews have found that when studies documented TNR colonies that declined in population, those declines were being driven primarily by substantial percentages of colony cats being permanently removed by a combination of rehoming and euthanasia on an ongoing basis, as well as by an unusually high rate of death and disappearance. TNR colonies often increase in population for a number of reasons: cats breed quickly, and the trapping and sterilization rates are frequently too low to stop this population growth; food is usually being provided to the cats; and public awareness of a TNR colony tends to encourage people in the surrounding community to dump their own unwanted pet cats there. The growing popularity of TNR, even near areas of particular ecological sensitivity, has been attributed in part to a lack of public interest regarding the environmental harm caused by feral cats, and the unwillingness of both scientific communities and TNR advocates to engage.

Terminology

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/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, then returns it to where it was found.

Advocacy and opposition

TNR as a method of managing free-roaming cat populations is controversial. Global attitudes towards these cats vary from those who see them as pets to those who target them as invasive species that need to be eliminated. Many international, national, and regional organizations and association, both professional and advocacy-based, have publicly aligned themselves into three 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. Organizations that oppose TNR on the basis of animal welfare and wildlife preservation include: Some organizations that conditionally support TNR include:

Advantages and disadvantages

Various studies and arguments have been presented both in support of and in opposition to free-roaming cats and TNR.

Purported reductions in population over time

In general, trap-neuter-release programs are not effective at reducing the population of feral cats, as they do not affect the carrying capacity of the environment. In order to be successful, a trap-neuter-release program must drive the net reproduction rate below 2 kittens per mother, which can be extremely difficult given the high reproductive capacity of feral cats (with a queen being capable of weaning about 9.4 kittens/year). 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. Reviews of these studies, as well as mathematical models of population growth, have shown that TNR colonies only decrease in population where cats experience very high rates of permanent removal (of at least 50% of the colony cats per year, such as by a combination of adoption and euthanasia), combined with high sterilization rates, and low rates of immigration of new cats into the colony. Unless all of these conditions are met, TNR colonies will not decrease in size over time. 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 illegally 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, California, 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 the cats that came in to the TNR colony had 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 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.

Euthanasia debate

TNR is often presented to public officials and policymakers as a viable alternative to euthanasia with several benefits.

Reducing euthanasia numbers

Cost savings

Improved morale and public support

Improving the cats' health and welfare

It has been claimed that TNR programs improve the welfare of free-roaming cats in many ways: Not all free-roaming cats, or cats that end up in live traps, are feral. Some are owned, but have been allowed to roam outdoors; some have escaped their homes or owners and are strays; some may have been abandoned or "dumped." The assessment, after trapping, of "social" (friendly and 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. The TNR process itself can result in inhumane outcomes. In 2016, investigative reporting by WFLA found that in Hillsborough County, Florida, TNR cats were being returned to the outdoors the day after their surgical sterilizations, because the Tampa Bay Humane Society did not have "a place to put them for a couple of days" where they could be observed in recuperation. WFLA said they had possession of images of TNR cats bleeding from opened surgical wounds, images of TNR cat with maggots in their incisions, and an image of a bloodied cat trap whose occupant had bled out; the TV station's managers declined to allow these images to be broadcast. Officials overseeing that TNR program said that their greatly reduced shelter euthanasia rates were worth it even if their TNR outcomes "weren't perfect".

Fewer complaints

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.

Effects on wildlife from hunting

Numerous studies have shown that free-roaming cats can have a significant negative impact on native wildlife through their predation. 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. Free-roaming domestic cats are considered an "alien" species and are listed as invasive in a multitude of countries around the world. 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 health

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. Free-roaming cat populations have been identified as a source for several zoonotic diseases that can and have affected humans, including:

Treatment by country

Domestic cats can be found on every continent except Antarctica. Of the 700million cats in the world, 480million of them are feral. 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 stray cats varies from location to location, as do the histories and efforts of TNR programs. There are numerous governments supporting trap–neuter–return.

Australia

In a 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 2million 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 was planned to continue until 2020.

Canada

Across Canada, municipalities have replaced 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 do not 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 stray 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.

Denmark

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.

France

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.

Israel

Like Turkey, Israel struggles with a continually increasing population of stray cats. Cats exist in every location with people, from the southernmost city of Eilat to communities in the Golan Heights. Moreover, it is illegal in Israel to remove cats from the streets as a result of pressure from Let the Animals Live. Due to large amounts of food left by people feeding them, colonies of cats are continuing to increase, with estimates putting the population within the city of Jerusalem at 2,000 cats per square kilometer. Efforts to trap, neuter, return the cats within Israel are not working, as the population is too large to feasibly catch enough cats to make a difference. Moreover, there is no national agreement on what to do regarding the cat population. As a result their population is increasing with no future plan of action. In January 2019, from a push by people who feed the cats, Jerusalem planned to instill "feeding stations" throughout the city. The goal was to facilitate specific areas for feeding to help the populations of stray cats and to improve their welfare. This plan was criticized by ecologists and conservationists, stating that it does nothing to help the welfare of the cats, with Amir Balaban of the Society for the Protection of Nature stating that "If someone cares about animals, they should take them home."

Italy

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.

South Korea

Negative attitudes towards cats in general and free-roaming cats in particular are culturally entrenched in South Korea. 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 feral cats has improved.

New Zealand

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. The Department of Conservation does not support TNR: "We don't support the 'trap, desex, release' approach to managing stray cats. This is because cats are predatory animals that continue to pose a threat to wildlife."

Turkey

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.

United Kingdom

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. In 2008, the Scottish Wildcat Association began utilizing TNR of feral cats to protect the regionally endangered Scottish wildcat. Their goals include:

United States

There is no federal law in the US that explicitly sets policy on feral cats, and state and local laws vary in their approaches. The Endangered Species Act and the Migratory Bird Treaty Act may be relevant to the legality of TNR. In a federal case, American Bird Conservancy v. Harvey (2014), conservationists sued Rose Harvey, the Commissioner of New York State Parks, under the Endangered Species Act for failing to prohibit activities supporting feral cats in a state park where the Piping Plover, a threatened species, was known to nest. Under a settlement and judicial order, the State of New York agreed to remove all of the cats to a shelter, and to trap and permanently remove any cats found in the park in the future. There are legal theories that TNR programs may have liability under the Migratory Bird Treaty Act of 1918, a strict liability statute that states that "it shall be unlawful at any time, by any means or in any manner, to pursue, hunt, take, capture, kill, attempt to take, capture, or kill[...] any migratory bird, any part, nest, or egg of any such bird," including unintentional taking, except if otherwise regulated or permitted by the government, and provides for criminal penalties of up to $15,000 in fines and up to six months of incarceration for each bird unlawfully taken. (An example of a successful prosecution under the MBTA was United States v. Moon Lake Electric Association Incorporated; in that case a power company was found guilty and sentenced to fines and probation because birds were being electrocuted on power poles that it owned.) Because TNR colonies are supported by people, it is possible that predation of birds by TNR cats might be ruled an illegal intentional take by the courts. 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, owing to a law against the release of cats into the wild, even if they were originally captured there. This has left trap-and-kill the only legal method of controlling the feral cat population there; however, the law against TNR is not well enforced and there are proposals to exempt sterilized cats from the rules. 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.