Feral cats are members of the domestic cat species just like pet cats. They typically live in groups called colonies and have strong social bonds with their colony members. Feral cats make their home where they can find food and shelter, often in close proximity to people. Because feral cats are not socialized or adoptable, they do not belong in animal shelters. Instead, they should be spayed/neutered, vaccinated and returned to their outdoor home.
Trap Neuter Vaccinate and Return
TNVR is the only effective and humane way to stabilize feral cat populations. Cats are humanely trapped and taken to a veterinarian, where they are neutered and vaccinated. Kittens and socialized cats may be able to be adopted out into loving homes while healthy adult cats are returned to their colony site, where they are often provided continuing care by dedicated volunteers.
The Vacuum Effect
Traditionally, the approach used by Animal Control agencies to manage the feral cat population did not work. Permanent removal of existing colonies created a vacuum. Once the established cats were removed, other cats moved in, taking advantage of the newly available resources and creating a new colony. Check out this article from Alley Cat Allies for more information on The Vacuum Effect as related to community/feral cats.