Feral cat rescue groups infiltrate colonies of feral cats in order to trap, spay or neuter, vaccinate, and return the cats to their colony in an effort to eliminate overpopulation without disturbing the ecosystem. Occasionally, feral cats and kittens are friendly enough to be adopted into a loving home.
Feral cat rescue groups practice the art of trap-neuter-return, or TNR. TNR controls the population of feral cats by eliminating their ability to reproduce. Volunteers first use humane traps to catch cats, and then take them to an animal shelter or selected veterinarian. The cats are spayed or neutered and vaccinated for rabies. While they are anesthetized for the procedure, the tip of their ear is removed. This provides a visual record that the cat has already been trapped, sterilized and vaccinated, which comes in handy when several volunteer groups are working to TNR a colony.
The benefits of TNR are not exclusive to feral cats. Humans living in areas with colonies notice a reduction in the pungent urine smell that comes from unneutered male cats. Additionally, the noises involved with feral colonies - screeching and fighting - decline. These sounds are typically associated with breeding, which no longer occurs once the colony is completely sterilized, and fighting, which decreases as the testosterone leaves the male cats' bodies.