Some feral cats may become more comfortable with people who regularly feed them, but even with long-term attempts at socialization, they usually remain aloof and reject human touch.
[21] A survey of rescue and veterinary facilities in the United States revealed that no widely accepted definition of a feral cat exists.
[23][24] However, even these so-called 'managed colonies' often have a devastating impact on wildlife as demonstrated in the decimation of native mammals in adjacent reserves, such as occurred with numbats and woylies in Western Australia.
Female farm cats show allomothering behaviour; they use communal nests and take care of kittens of other colony members.
[30] The need to keep rodents from consuming or contaminating grain crops stored for later human consumption may be the original reason that cats were domesticated.
This variance is often due to breeding season, access to females, whether the cat is neutered, age, time of day, and availability of prey.
Colonies and stray feral cats will settle in urban, suburban, and rural developments like cities and farms, wherever they can find easy access to food or prey animals.
[17] In a 2010 interview survey with veterinarians and rescuers in the United States, 66% of respondents had socialization programs for kittens, and 8% for adult cats.
[70] They prey on a wide variety of both vertebrates and invertebrates, and typically prefer smaller animals with body weights under 100 g (3.5 oz), particularly mammals, birds, and lizards.
[57] In Australia, they prey on introduced species like the European rabbit and house mouse, and on native rodents and marsupials, particularly the common ringtail possum.
[76] A further study of over 100,000 feral and stray cats admitted to TNR programs in diverse locations of the U.S. resulted in the same 0.4% rate of euthanasia for debilitating conditions.
[84][85] Researchers studying 553 feral cats in North Florida in the United States tested them for a number of infections that could be detrimental to feline or human health.
The study found the most prevalent infection to be Bartonella henselae, the cause of cat-scratch disease in humans, with 33.6% of the cats testing positive.
[83] Although some colony management programs involve administering rabies vaccines, the need to revaccinate every few years makes this challenging to maintain.
[83] The study of feral cats on Prince Edward Island warned of "considerable zoonotic risk" for transmission of intestinal parasites.
[80][81][95] TNR results in fewer complaints, as nuisance behaviors diminish following neutering,[95]: 16 and the quality of life of the cats is improved.
[78][79]: 1359 The practice is reported to save money[95]: 294 and garner more public support and better morale than efforts that involve killing cats.
164 The International Companion Animal Management Coalition advocates for TNR as a humane method of controlling feral cat populations.
[110][111] In the US, the American Veterinary Medical Association (AVMA), in 2016, adopted a resolution that "encourages collaborative efforts to identify humane and effective alternatives to the destruction of healthy cats for animal control purposes, while minimizing their negative impact on native wildlife and public health.
Members of the public often begin dumping unwanted pet cats at TNR sites, increasing the rate of recruitment.
TNR programs are sometimes able to attain local reductions in the numbers of cats at specific colony locations, but it has never been demonstrated to meaningfully impact cat populations over large areas or regions, because the effort necessary to maintain sufficient sterilisation rates means that systemic TNR will never be a credible option.
Another perspective emphasizes the poor outdoor living conditions of feral cats, and advocates for rehoming, adoption, or euthanasia as a more ethical response.
In Mandurah, Western Australia, a single, neutered, semi-feral cat raided a protected fairy tern colony on at least six nights in November 2018.
[120] This new dynamic may prove to be more harmful, with further upstream[clarification needed] effects on the ecosystem that were not predicted before removal of the feral cat population.
[122] In Australia, domestic cats were introduced in the 1800s to settlements that had developed near gold mining sites and farms as a pest control strategy to decimate rabbits, mice, and rats.
They have contributed to the extinction of more than 20 Australian mammal species, including the pig-footed bandicoots, lesser bilby and broad-faced potoroo.
[124] Even well-fed domestic cats may hunt and kill, mainly catching small mammals such as rodents and lagamorphs, but also birds, reptiles, amphibians, fish, and invertebrates.
[131] In Hawaii's remote, mountainous areas, they destroy the nests of seabirds including Newell's shearwater (Puffinus newelli) and the Hawaiian petrel (Pterodroma sandwichensis), amongst many other ground-nesting birds.
[132] In agricultural settings, cats can be effective at keeping mouse and rat populations low, but only if rodent harborage locations (such as tall grass) are kept under control.
[140] High levels of hybridisation have led to difficulties in distinguishing pure wildcats from feral and domestic cats, which can complicate conservation efforts.