I have several outdoor cats on my 11acres, only one of them pays any attention to the chickens. When the girls are free ranging he pays them no attention, but when they're in their out side yard he used to jump in and chase them (never caught one, so I'm not sure if he was seriously trying). Most of the yard is covered with bird net and the rest is open. I found he was climbing a wooden post to jump in, so now I have large buckets upside down on the posts. Looks funny, but works. Everyone else ignores them. Having said that definitely keep young chicks secured.