I have a homeless cat who has adopted us.
She lives right behind the henhouse and stalks mice at night.
During the day she takes cover, because THE HENS will mess with HER if she doesn't!
I have an indoor cat who can be trusted with BABY CHICKS! The first year, I'd lock her in another room while I was cleaning the baby chicks cage or taking their pictures.
But then she got out one day and I found her just staring at the baby chicks (who we keep in a clear Rubbermaid container). She could have messed with them if he had wanted to, but all she did was watch them.
That is when I discovered that she could be trusted around chickens -- even day old babies.
Since then, I have let her in the room with the brooder with no restriction. And she loves it -- great entertainment for her, sitting there watching those baby chicks play in that brooder.
That cat goes outside and for the most part she stays away from the chickens. Every now and then you see her and the chickens mix it up, but when they do, all they will do is chase one another. Sometimes she chases a hen, sometimes a hen chases her -- but MOST of the time time, they just don't mess with one another.
Of course, we keep our cats well fed!