Feral cats live in the wild, and are the progeny of cats that were once domesticated, and lived with people as pets. Although these cats are descended from domestic breeds, they do not retain many domestic traits. They are, however, nearly identical in appearance to domesticated cats. The average house cat and a feral cat share a similar body size and coloring, though some feral cats may appear slightly smaller due to the lack of a consistent food supply. Usually, however, the two are indistinguishable by physical features alone.
Wild cats often live together in colonies for basic survival purposes. These colonies ensure that the cats have easier access to food and better protection from predators. This communal behavior does not eliminate all threats, however. Parasitic infections, diseases caused by microorganisms, and territorial disputes between males commonly lead to death prior to old age. Some feral cats, especially males, prefer to live on their own, which reduces their life expectancy.
A feral cat is not naturally predisposed to survival outside of human care. The practice of taming cats for domestic purposes dates as far back as 9500 BCE, and cats have developed a reliance on humans as their primary source of food, shelter, and protection against predators and disease. Thus, cats are usually at a disadvantage in the wild, possessing fewer survival traits and weaker immune systems than other wild cats. Feral cats have an average life span of five years if they live in a colony and only two years if they live on their own.
Cats are not native to many parts of the world, and feral cat populations were originally introduced by travelers in an attempt to control overgrown rabbit populations. The native animal populations were often unfamiliar with these cats, which have, at times, decimated native animal populations, significantly altering the balance of an area's ecosystem. Their populations can run rampant, ravaging a native ecosystem, especially island ecosystems.
Different methods have been proposed to deal with the growing population of feral cats. Many advocate a system of trapping the cats in order to spay or neuter them. After sterilization, the cats are released back into the wild. Others promote euthanization as the best course of action, which is achieved through a number of methods. Feral cats can be hunted by humans, poisoned, or exposed to biological agents, such as feline specific viruses or predators that hunt them.