 Even in places with ancient and numerous cat populations , such as Western Europe , cats appear to be growing in number and independently of their environments ' carrying capacity ( such as the numbers of prey available ) . This may be explained , at least in part , by an abundance of food , from sources including feeding by pet owners and scavenging . For instance , research in Britain suggests that a high proportion of cats hunt only " recreationally " . And in South Sweden , where research in 1982 found that the population density of cats was as high as 2 @,@ 000 per square kilometre ( 5 @,@ 200 / sq mi ) . 
