From “Neighborhood Cats”:
A “feral” cat is a cat who has reverted in some degree to a wild state. They originate from former domestic cats who were lost or abandoned and then learned to live outdoors or in environments involving little human contact, such as warehouses, factories or abandoned buildings. In most cases, feral cats are not completely wild because they still depend on people for their food source, whether it’s a caretaker who comes by once or twice a day, a dumpster outside a restaurant, garbage cans, or the like. Relatively few feral cats subsist only by hunting.
To what degree a feral cat is wild depends on several factors. Foremost, is the age of the cat. Young kittens are more capable of being socialized and successfully re-introduced to domestic life than a feral adult. Another factor is what generation feral is the cat. A kitten born outdoors to a mother who was herself formerly domestic is likely to socialize easier than one born to a mother who is seventh generation feral. The extent of daily human contact also plays an important role in determining how wild a cat will be. If cats have regular interaction with people, such as in a community garden, they will tend to be friendlier and more approachable than if they live in a back alley where people rarely venture. Finally, there’s the wild card factor, which is the particular cat’s personality. It’s not unheard of for someone to tame an older, multi-generational feral who has been largely isolated from people, but this is the exception.
It’s important to recognize that if a cat is truly feral, then the most compassionate choice might be to allow them to live outdoors. Trying to domesticate them would be no different than trying to make a squirrel or a raccoon a household companion – you might succeed somewhat, but never fully and only with a great deal of time and patience. Moreover, you would not be permitting the animal to live in a manner that suits him best. Many well-meaning people, convinced they are “saving” a feral cat by bringing him indoors, end up condemning the poor creature to a life of hiding under the bed and being in constant fear.
Trap-Neuter-Return (TNR) respects a feral cat’s wild state. The neutering of the ferals prevents tremendous suffering and shields the cats from the hostility their behavior might otherwise draw from human neighbors. But the return of them to their own territory and the providing of adequate food and shelter gives them the opportunity to live among their own, to be free and to answer to their own unique natures.