Is feral cat predation on our fauna sustainable? I'll answer that question with another. Is there a valid reason we should risk the extinction of more of our wildlife to find out? Feral cats are the unwanted discards of our society, living their lives on the edge. Most survive day to day, if they manage to dodge cars, dogs, coyotes, raccoons, traps set to catch them, and disease, then find a human to feed them, or another animal to kill.
There is growing evidence their millions are changing our environment, and feeding that change with the meat torn from their bodies by an increasing number of coyotes. What further changes will this hungry population of coyotes bring, with them coming into our neighborhoods to hunt the cats they're competing with for their natural prey animals? Is there a valid reason we should wait to find out?