A feral cat is a descendant of a domesticated cat that
has returned to the wild. It is distinguished from a stray cat, which is a pet
cat that has been lost or abandoned, while feral cats are born in the wild. The
offspring of a stray cat can be considered feral if born in the wild.
In many parts of the world, feral cats are descendants of domestic cats that were left behind by travellers. Because cats are not native to all parts of the world, feral cats can cause harm to local environments by preying on local species. This is especially true on islands where feral cats have sometimes had a substantial and deleterious effect on the local fauna.
Feral versus stray
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-defence behaviours, 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 behaviours are established. Such behaviours are established while it is still a kitten being raised by its mother.
Life span and survival
The lifespan of feral cats is hard to determine accurately, although one study reported a median age of 4.7 years, with a range between 0 to 8.3 years, while another paper referenced a mean life span of 2 – 8 years. For contrast, in captivity, an average life expectancy for male indoor cats at birth is 12 to 14 years, with females usually living a year or two longer.
A feral cat colony (or "clowder") 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, causing them to be anemic. Both the fleas, and the food source, if limited to garbage and rodents, cause the cats to have intestinal micro-organisms (such as coccidia or giardia) and other parasites (commonly known as roundworms, tapeworms, and hookworms), which lead to diarrhoea 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 leukaemia due to the constant transmission of blood and bodily fluids via fighting and sexual activity.
While all of these illnesses are quite treatable, there must be humans to intervene to stop these illnesses from becoming fatal. Due to the number of health problems to which they are subjected, and their fragile immune systems, kittens in the clowders usually do not survive.
How Feral is Feral
Feral cats are wild animals. Some are abandoned pets; others are born in the wild to existing ferals or to strays. Kittens born in the wild, with no exposure to humans during the socialisation period (3-8 weeks) become wild animals. Many ferals approach familiar people for food and some become tame through regular contact, or are tamed by carers. Farm cats (barn cats) are often considered to be "semi-feral" or "semi-tame" since they are accustomed to some (albeit limited) interaction with humans. In Scotland, feral cats have hybridized extensively with the indigenous Scottish Wildcat (F sylvestris), creating mongrel wildcats, including the large, black wildcat hybrids known as 'Kellas cats' or 'Moray cats'.
In fact, according to some researchers, traditional conservation efforts to protect the "pure" Scottish wildcat may be misguided. It has interbred with domestic cats for around 2000 years, so long that it no longer makes sense to preserve it as a separate pure-bred species since genetic tests put its purity in doubt. They argue that the replacement of wildcats by more adaptable hybrids is evolution in action. Although wildlife groups will disagree, some researchers argue that the pure wildcat should only be protected if it plays an important role in the local ecosystem.
Hybridization of domestic cats with wildcat species to create new breeds could lead to an infusion of wildcat genes into the feral population of Britain. 90% of domestic cats are indoor-outdoor pets and up to 20% of tomcats are non neutered; and rescue shelters encounter pedigree cats which have gone feral after straying or being abandoned. I have encountered a completely feral Persian and knew of an Unneutered Persian tomcat living wild. The owner considered this to be a natural lifestyle for her cat, despite the fact that Persians are a far cry from their wild ancestors. I have heard of a Blue-point Birman gone feral and breeding, and of rogue breeders with "colonies" of never-handled Burmese and Siamese cats whose unsocialised kittens are sold as pets. One irresponsible breeder/owner dumped over 20 purebred white Persians in woodland to fend for themselves. Abandoned cats, will often join feral colonies, attracted to whatever food source is maintaining the feral colony.