My neighbor just across the road has lost 5 four month old chickens to a cat that killed them. She saw the cat and described it to me. I have been watching, and 2 weeks ago, I chased it out of my yard. If it comes back again, I will kill it. I am not letting it kill my chickens.
It killed her chickens in two days. Only ate part of one each time but killed more. These were pretty good sized chickens. I guess it just depends on the size of area the chickens are pinned up in, and also the breed. Some are just more docile and don't try to defend themselves but just panic.