Secure you birds in a coop and run that the cats can't get into. I live in the woods and we have lots of predators including feral cats. The feral cat problem is way out of control I don't poison them and don't suggest doing that. A secure coop and run sounds like your answer. It is a win win for you, cat problem solved and chickens wandering out of their own yard. Sounds like you live in a town so even though you like your chickens wandering free, your neighbors might not!
