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A feral cat is a domesticated cat that has returned to the wild, or the descendants of such an animal. It is distinguished from a stray cat, which is a pet cat that has been lost or abandoned, while feral cats have never been socialized. The offspring of a stray cat can be considered feral if born in the wild. In many parts of the world, feral cats are the offspring of unaltered domestic cats.
The term "feral" is sometimes used to refer to an animal that does not appear friendly when approached by humans, but the term can apply to any domesticated animal without human contact. Hissing and growling are self-defense behaviors, which, over time, may change as the animal (whether "feral" or "stray") begins to trust humans that provide food, water, and care.
Feral cats that are born and living outdoors, without any human contact or care, have been shown to be adoptable and can be tamed by humans, provided they are removed from a wild environment before truly feral behaviors are established. Such behaviors are established while it is still a kitten being raised by its mother.
Feral cats in managed colonies can live long lives. A number of cats in managed colonies in the U.K. died of old age.:522 In the U.S., the last cat in a managed colony in Washington, D.C. died at age 17; and Zorro, the last cat of a colony at the Merrimack River in Newburyport, Massachusetts, died in 2009 at age 16.
A long-term study of a trap-neuter-return (TNR) program in Central Florida found that despite widespread concern about the welfare of free-roaming cats, 83% of the cats studied had been present for over six years, with almost half first observed as adults of unknown age. These time spans compared favourably to the average lifespan of 7.1 years for pet cats reported in a 1984 study,:45 and to the finding that only 42% of the pet cat population in the U.S. is more than 5 years old.:1358
Without human assistance, feral kittens are expected to have a high death rate.:45
Adult feral cats without human assistance have been found in surprisingly good condition. In Florida, a study of feral cats admitted to a trap-neuter-return (TNR) program concluded that "euthanasia for debilitated cats for humane reasons is rarely necessary". A further study of over 100,000 community cats (feral and stray) admitted to TNR programs in diverse locations of the U.S. resulted in the same 0.4% rate of euthanasia for debilitating conditions. Rates of Feline leukemia virus infection and Feline immunodeficiency virus antibodies in feral cats studied in North Carolina and Florida were similar to those of owned cats. The body condition of feral cats entering a TNR program in Florida was described as "generally lean but not emaciated". However, many community cats had suffered from parasites such as fleas and ear mites before entering TNR programs.
Trap-Neuter-Return (TNR) involves trapping feral cats, spaying or neutering them, and then returning them to the place where there were originally trapped; where ongoing care is provided by caregivers. When neutered, the cats receive vaccinations against rabies, and attention to other medical needs, such as dental care and flea treatments.:115 TNR programs are prevalent in several countries, including England, Italy, Canada and the United States, supported by many local and state governments. Various long-term studies have shown that TNR is effective in stopping reproduction and reducing the population over time. TNR results in fewer complaints, as nuisance behaviors diminish following neutering,:16 and the quality of life of the cats is improved.:1359 The practice is reported to save money,:294 and garner more public support and better morale, than efforts that involve killing cats.:297:49
The International Companion Animal Management Coalition advocates for TNR as a humane method of controlling feral cat populations. In the U.S., the practice is endorsed by the Humane Society of the United States and the National Animal Control Association. While the United States Department of Defense does not formally advocate TNR, it provides information to military installations on how to implement TNR programs; with the main message that population control programs must be humane.
During the Age of Discovery, ships released rabbits onto islands to provide a future food source for other travelers. They eventually multiplied out of control and cats were introduced to keep their numbers, and that of mice and rats, down. The cats tended to favor local species as they were ecologically naive and easier to hunt. Their numbers, too, increased dramatically and soon they colonised many areas and were seen as pests. Cats were introduced to Tasmania in 1804 and had become feral by the 1840s. Feral cats were reported on mainland Australia around Sydney in 1820. It has been suggested that feral cats could have been introduced accidentally to the north-western coast in the 17th century from the wrecks of Dutch ships; alternatively, they could have arrived earlier, possibly around the fifteenth century, via mariners from Indonesia.
Feral cats living in managed colonies are fed kibble and/or wet food by volunteers.
Domestic and feral cats have generally been found to eat a very broad range of vertebrate and invertebrate prey. Preferred prey usually are small mammals, birds and lizards, especially those with body weights under 100g. Feral cats in Australia prey on a variety of wildlife. In arid and semi-arid environments they eat mostly introduced European rabbits and house mice. In arid environments where rabbits do not occur, native rodents are taken. In forests and urbanised areas, they eat mostly native marsupial, birds and reptiles. On Macaronesian islands, cats prey mainly on introduced mammals but also on birds and reptiles.
Feral cats may be apex predators in some local ecosystems. In others, they may be preyed on by feral dogs, dingoes, coyotes, wolves, bears, cougars, leopards, bobcats, lynx, hyenas, fishers, crocodiles, snakes, foxes and birds of prey.
For thousands of years, cats have been known for their ability to hunt mice and rats and keep their populations under control. This ability is understood as the reason for cats becoming domesticated.:68 The relationship was more of convenience (or mutualistic) than dependence: "Cats killed mice and rats, and humans provided lots of mice and rats to kill since mice and rats lived in human settlements.":68 A 2014 study of cat remains dating 5,300 years before the study, at an agricultural village of Quanhucun, China provides early evidence of this dynamic, where cats protected grain stores by eating rodents.
If they are well-fed, farm cats are more dependable as effective ratters, as they are less likely to stray or hunt further afield.:110 Cats are wary of adult rats, given their size,:111 but are particularly adept at hunting young rats.:110
In 2002, feral cats introduced to a flower market in Los Angeles, California, were noted to have helped lower rat populations. In Chicago's 47th Ward, feral cats were introduced in 2012 to help the city deal with the rat problem there.
Efforts to eradicate feral cats in Ventura, California were noted in 2002 to have resulted in increasing numbers of rats, which were being monitored for health problems such as bubonic plague.
A 2013 study by Scott R. Loss and others of the Smithsonian Conservation Biology Institute and the US Fish and Wildlife Service, suggested that free-ranging domestic cats (mostly unowned) are the top human-caused threat to wildlife in the United States, killing an estimated 1.3 to 4 billion birds and 6.3 to 22.3 billion mammals annually. These figures were much higher than previous estimates for the U.S.:2 Unspecified species of birds native to the U.S., and mammals including mice, shrews, voles, squirrels and rabbits were considered most likely to be preyed upon by cats.:4
Advocates for feral cats counter that Loss' study and earlier related studies have inflated estimates of wildlife killed by cats in the U.S., based on unscientific research that extrapolates from tiny samples and projects them onto whole nations. One reviewer stated that Loss' study was filled with "numerous major ﬂaws in the statistical arguments made" that in his view made it "unacceptable for publication".:1 It was unclear how predation rates were obtained, and then "applying these estimates to all cats across the country is highly questionable.":3 Extrapolation was also misused when "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.":3
Perhaps the first U.S. study that pointed to predation by cats on wildlife as a concern was ornithologist Edward Howe Forbush's 1916 report for the Massachusetts State Board of Agriculture, The Domestic Cat: Bird Killer, Mouser and Destroyer of Wildlife: Means of Utilizing and Controlling It.
U.K. biologist and cat behaviour expert Roger Tabor states that "studies from all around the world have found that cats catch relatively few birds compared to small mammals.":135 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." 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
Island settings pose particular challenges for wildlife. A 2001 study identified cats alone as responsible for the plight of some island bird species, such as the Townsend's Shearwater, Socorro Dove, and the Marquesan Ground Dove.:400 The same study identified the greatest cause of endangerment of birds as habitat loss and degradation, with at least 52% of endangered birds affected,:399 while introduced species on islands, such as domestic cats, rats and mustelids,:403 affected only 6% of endangered birds.:399 Other studies caution that removing domestic cats from islands can have unintended consequences, as increasing rat populations can put native bird and mammal species at risk.
Feral cats in Australia have been linked to the decline and extinction of various native animals. They have been shown to cause a significant impact on ground nesting birds and small native mammals. Feral cats have also hampered any attempts to re-introduce threatened species back into areas where they have become extinct as the cats have hunted and killed the newly released animals. Numerous Australian environmentalists claim the feral cat has been an ecological disaster in Australia, inhabiting most ecosystems except dense rainforest, and being implicated in the extinction of several marsupial and placental mammal species.
The fauna of New Zealand has evolved in isolation for millions of years without the presence of mammals (apart from a few bat species). Consequently, birds dominated the niches occupied by mammals and many became flightless. The introduction of mammals after settlement by Māori from about the 12th century had a huge effect on the indigenous biodiversity. European explorers and settlers brought cats on their ships and the presence of feral cats were recorded from the latter decades of the 19th century. It is estimated that feral cats have been responsible for the extinction of six endemic bird species and over 70 localised subspecies as well as depleting bird and lizard species.
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 owned cats access to the outdoors, which is recommended to prevent feline obesity (p. 138), and behavior problems and other health problems arising from confinement stress (p. 121).
Many islands host ecologically naive animal species; that is, animals that do not have predator responses for dealing with predators such as cats. Feral cats introduced to such islands have had a devastating impact on these islands' biodiversity. They have been implicated in the extinction of several species and local extinctions, such as the hutias from the Caribbean, the Guadalupe Storm Petrel from Pacific Mexico, the Stephens Island wren; in a statistical study, they were a significant cause for the extinction of 40% of the species studied. Moors and Atkinson wrote, in 1984, "No other alien predator has had such a universally damaging effect."
Feral cats, along with rabbits, some sea birds, and sheep, form the entire large animal population of the remote Kerguelen Islands in the southern Indian Ocean. Although exotic mammals form the bulk of the diet, cat's impact on seabirds is very important.
Because of the damage cats cause in islands and some ecosystems, many conservationists working in the field of island restoration have worked to remove feral cats. (Island restoration involves the removal of introduced species and reintroducing native species). As of 2004, 48 islands have had their feral cat populations eradicated, including New Zealand's network of offshore island bird reserves, and Australia's Macquarie Island. Larger projects have also been undertaken, including their complete removal from Ascension Island. The cats, introduced in the 19th century, caused a collapse in populations of nesting seabirds. The project to remove them from the island began in 2002, and the island was cleared of cats by 2004. Since then, seven species of seabird that had not nested on the island for 100 years have returned.
In some cases, the removal of cats had unintended consequences. An example is Macquarie Island (off the coast of Tasmania), where the removal of cats caused an explosion in the number of rabbits, rats, and mice that harm native seabirds even if the eradication was positioned within an integrated pest management framework. The removal of the rats and rabbits was scheduled for 2007 and it could take up to seven years and cost $24 million.
Feral cats have interbred with wildcats to various extents throughout the world, the first reported case occurring more than 200 years ago. The significance of hybridisation is disputed. Some old books suggested that the wildcat was a separate species to the domestic cat, but modern genetic analysis has shown that the domestic cat is a domesticated version of the near eastern wildcat (Felis sylvestra lybica), which is of the same species as the European Wildcat (Felis sylvestris sylvestris). In some locations, high levels of hybridisation has led to difficulties in distinguishing a "true" wildcat from feral domestic and domestic hybrid cats, which can complicate conservation efforts. Some researchers argue that "pure" wildcats do not exist anymore, but others dispute this. One study in Scotland suggests that while "true" Scottish wildcats are unlikely to exist, the current wildcat population is distinct enough from domestic cats to be worth protecting. In addition to Scotland, wildcat populations notable gene introgression exist also in Italy, Hungary, Spain and Portugal. For a discussion of this issue see The Encyclopedia of Mammals, OUP, pages 656–657.
Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are among the most common infectious diseases of cats. FeLV and FIV belong to the retroviridae family, and both cause immunosuppression in cats. Research has shown that the prevalence of these viruses among feral cat populations is low and are similar to prevalence rates for owned cats in the United States.
A feral cat colony is a population of feral cats. The term is used primarily when a noticeable population of feral cats live together in a specific location and use a common food source. The term is not typically applied to solitary cats passing through an area. A clowder can range from 3–25 cats. Their locations vary, some hiding in alleyways or in large parks.
Members consist of adult females, their young, and some adult males. Unneutered males in a clowder fight each other for territory and for females. Some will be driven out to find another place to live.
Feral cats who have been trapped in many warm areas where fleas exist are usually found to have a large number of fleas, making them anemic. Both the fleas, and the food source, if limited to garbage and rodents, cause the cats to have intestinal microorganisms (such as coccidia or giardia) and other parasites (commonly known as roundworms, tapeworms, and hookworms), which lead to diarrhea and subsequent dehydration. They also can have ear mites, ringworm, and upper respiratory infections. Others are wounded in mating-fights and die from the infected wounds. Still others eventually contract feline immunodeficiency virus or feline leukemia due to the constant transmission of blood and bodily fluids via fighting and sexual activity.
While all of these illnesses are quite treatable, human intervention is necessary to prevent them from becoming fatal.
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