We have 2 barn cats that take down mice, reptiles, & birds. Lots of birds! But, they usually leave the 5 month old chickens alone. Then, out of the blue, one cat goes after the chickens twice in the same morning. I'm not sure if he was just playing, really hungry, or now sees them as pray. That was last week. We decided, 3rd strike, he's out (of a home). He's very affectionate so we'll find him a new home.