I have been letting my chickens free range with there rooster for about 3 months now and have had no problems. I know free ranging is risky but they love it! We live on 5 acres and they have lots of trees and other things to hide under, they are about 7 mo old and full grown. Today I was sitting inside and heard a different noise out of a hen and then I heard our rooster so I ran outside and they were all just standing around.. I didn't even think to count them.. Now this evening I go out and one of our RIR girls is gone there are no feathers anywhere, no signs of anything and she was full grown! Could a hawk pick her up and take her away? It also could of been another predator I just feel like if it was a fox or something I would of seen feathers or the other girls would of got scared when it happened..