My seven cats from my previous marriage (my ex has custody) always co-existed with our chickens, even one day old's. But they had a very responsible roster guarding them. Now I have seven cats again, most of them rescued ferals, and I wouldn't trust them for a second with my small chickens. Everything here is cat-proof. Even the incubator has a ventilated cuboard of it's own. One of the cats though, our Sasha, consider the chickens as family and would defend them agains the other cats. I don't find it difficult to solve though. It is just for a short period of time. I have an old transport gage for dogs with som chicken wire as brooder and the cats sleep on top of it. Once the chickens are big there is no problem. I have even had bantams that moves the cats out of their way. Now I have tandard cochins so they are bigger than the cats and definitely in charge.