Cats as hunters have raised considerable interest about breeding hunting out of house tabbies at Rabett Run, but the real problems are feral cats, and the real serious problem is feral cats on remote islands. Birds, of course can fly, often considerable distances and over the eons have populated remote islands which mammals can't swim to. OTOH, they can hitch rides with people in boats and they have done so with a vengeance, none more successfully than Brother Rat and Sister Cat, and to an extent Cousin Rabett.
Birds on these islands have, again over the eons, have lost their native caution of hunting animals and protecting their nests and eggs from other beasts. It is only relatively recently that eradication programs have started to rid some of these islands of the feline predators, but it is not a trivial thing. Kill the cats, and you have the rats which are harder to get rid of and breed like crazy. This is, also true of rabbits who leave the birds alone but eat the leaves down to the soil.
Feral cats do not seem to become well established in areas with “mesopredators” whichCoyotes, as Kevin Drum discovered to his dismay, like cat treats. Since humans bond with cats this is often hard on the humans, but when too many cats disappear it does not go well for the coyotes. There is a considerable literature on all this.
either compete with or prey upon cats. In New Zealand, Taylor (1984) suggests that stoats (Mustela erminea) outcompete feral cats, restricting their presence to larger islands and to areas either with rabbits or close to human habitation. Coyotes (Canis latrans) control cats in coastal southern California (Crooks and Soule 1999).