They arrived in the US several hundred years ago. The first type creates no known environmental problem. The feral cat is a domestic house cat that has been abandoned to live in the wild or one that has strayed into or been born in the wild.
Feral cats are often much larger than domestic ones.
While they climb trees, they do it poorly and rarely can get to tree bird nests. They are carnivores and lizards are a prey of considerable importance and thus of local concern where such species are threatened or increases are desired, There are relatively few management techniques for reducing feral cat populations. Recent studies are reported, but it is important to emphasize that other studies are needed to gain a better understanding of feral cat population and how to control them. Feral cats are extremely efficient at preying on small birds and mammals. The general public typically only sees cats as a way of removing pest species and as pets, but they are also direct competitors with declining raptor populations and destructive to native species.