While catching and removing cats may temporarily reduce the number of cats in a given area, it is ultimately counterproductive. Removing cats only creates a vacuum that will soon be filled by nearby cats, who move in to use the resources that sustained the cats who were removed. These cats breed and the area is soon populated again. This phenomenon is known as the Vacuum Effect and has been documented worldwide in many species, including coyotes and foxes. Because of the Vacuum Effect, catching and removing cats is an endless, ineffective cycle.