Feral cat

A feral cat or a stray cat is an unowned domestic cat (Felis catus) that lives outdoors and avoids human contact; it does not allow itself to be handled or touched, and usually remains hidden from humans. Feral cats may breed over dozens of generations and become a local apex predator in urban, savannah and bushland environments, and especially on islands where native animals did not evolve alongside predators. Some feral cats may become more comfortable with people who regularly feed them, but even with long-term attempts at socialization, they usually remain aloof and reject human touch. Of the 700 million cats in the world, an estimated 480 million are feral.

Feral cats are devastating to wildlife, and conservation biologists consider them to be one of the worst invasive species on Earth. They are included in the list of the world's 100 worst invasive alien species. Attempts to control feral cat populations are widespread but generally of greatest impact within purpose-fenced reserves.

Some animal rights groups advocate for trap–neuter–return (TNR) programs, also known as trap-neuter-vaccinate-release (TNVR) programs, to prevent feral cats from breeding and being nuisances by spraying urine and fighting over territory. Scientific evidence has demonstrated that TNR is not effective at controlling feral cat populations alone and must be done alongside removal. For TNR to be effective, at least 88% of the cat colony should be neutered which is an unrealistic goal in majority of cases, and any lower rates actually increase cat populations. TNR also takes much longer to eliminate cat colonies as compared to trap and euthanasia and it is more expensive and resource-intensive. TNR receives many criticisms of it being inhumane, to the point that some say that TNR stands for trap-neuter-reabandon, because feral cats do not have good lives and die early from disease, poisoning, predation, vehicle collisions and sometimes violence by humans. A possibly more effective alternative to TNR has been proposed, which is trap-vasectomy-hysterectomy-release (TVHR).