Vaccum Effect

Animal control’s traditional approach for feral cats – catch and kill – is endless and cruel, and it does not keep an area free of cats. Cats choose to reside in a location for two reasons: there is a food source (intended or not) and shelter. Because of a phenomenon called the vacuum effect, when cats are removed from a location, survivors of the catch and kill effort and new cats who have moved in breed to capacity. Cats have been living outside alongside people for 10,000 years – a fact that cannot be changed.  

The vacuum effect is well-documented among biologists and scientific research has observed the phenomenon across many species – herbivores, carnivores, and omnivores. A habitat will support a population of a certain size. No matter how many animals are removed, if the resources remain, the population will eventually rebound.   

Trap-Neuter-Return (TNR) is the most effective and humane method of controlling populations of feral cats.  

TNR is a spay/neuter initiative to reduce the feral cat population by managing existing colonies and preventing future litters.  

TNR benefits not only the cats but also the community in which they live. Cats are trapped, spayed or neutered, vaccinated and ear tipped before being returned to their outdoor home. The size of the colony stabilizes with no new additions. Without the stress associated with mating, cats are healthier and the behaviors associated with mating are eliminated.