The 1 acre property I bought last October, 2006, came complete with alot of free range chickens and several semi-feral cats. The owner had died in April and the critters were all on their own until late May. I know that the cats were he** on the baby chicks.
All summer, we fed everyone, but when the chickens would hatch out babies, the babies would dissappear, a few at a time. It'd take several days. Very discouraging for me, the new-chicken-owner.
Even late this summer, when the cats were being fed daily, we had a black hen show up with 5 babies. Didn't take a week to lose them all--babies, that is, Momma was fine. (This was before I found this website!)
Now, I'm ready with nest boxes and hoop coops to protect the hens and chicks this coming summer.
Also, the four cats (all neutered) seems to respect the full grown chickens--and it's a common sight for them to all be out in the sunshine together. I don't trust the cats with the chicks. I am hoping that everyone will co-exist this year, but hedging my bets with the hoop coops.