The rather large Cooper's hawk that killed my 6 month old hen earlier last year appeared to have chased her down, all over the yard, under trees and bushes, and back under the redwood trees where he caught up with her -- there were piles of feathers found under bushes here and there where she most likely tried to hide -- I appeared on the scene as the hawk was eating her there on the ground, her head was already gone. She wasn't full grown but she wasn't particularly petite either. It was shocking, it was awful! I let the hens free range when I'm around to keep an eye to the sky, but as the hawks start coming back this month, the girls will spend much more time closed in the enclosure with the netting roof over it. I gather other hawks like to swoop down and can be deterred a bit but it looks like the Cooper's aren't stopped by much.