We had a smallish hawk (sharp-shinned I think) attack one of our full-grown guinea hens just outside of the coop many years ago. The hawk was on top of the hen, plucking away at the feathers on her back, when I ran out to try to rescue her. Thankfully, I got there in time. The hawk flew off as I got close, but the hen just laid there and didn't move. I picked her up, expecting that she was already dead, but she lifted her head and started to struggle in my arms. She took a couple of days to recover from the shock of it all, but she steadily improved after that, and except for a few bald patches on her back, she was back to her old self in a week or so. I'm sure that the hawk would have finished her off if I hadn't scared him off.
Many years later, another small hawk swooped down and tried to get one of my oldest hens. The hen shrieked and ran off, and the hawk missed her. I think that one was probably a young hawk that wasn't very experienced in the art of hunting.
Around here in New Hampshire, I'd have to say that hawks are the number one predator to worry about when it comes to our poultry.