I have 9 cats, 6 are indoor/outdoor, and 3 are outdoors. We also feed the stray barn cats that come around, and there are a couple ferals too. None of them have ever bothers the chickens. Our biggest guy is close to 18lbs and he come with me when I go into the run to sit with the chickens. He just sits on my lap and looks at them. They other day, one of the smaller hens walked over my feet, and her body brushed up again the cat on my lap. Ozzy did not even try to go after her, and I think he may have been asleep. We also have a 1yr old indoor/outdoor that guards the chickens when they free range. She will lay in the goat pen(where the chickens are allowed to roam) and if a chicken strays from the group, she will fake chase it back. She pounces at it, but never gets closer than 4 feet from it. The chicken freaks out, run back to the group, and the cat lays back down. I've caught a few ferals in the goat pen too with the chickens, but they have never advanced. They just sit there and watch from a distance.