This is about the third time this has happened. We scare a hawk off a seemingly dead hen, but when we get to her she's still breathing. We look and we see no injuries, but the birds chest is heaving, the head is twisted and the eyes are closed showing the white eyelids of death, with looks much different from a sleeping chicken.
We've seen this before. A chicken can get so stressed is falls down as if dead. About half of the time they recover. It's an amazing thing to see. You go from a hawk standing on a bird ready for dinner to, 20 minutes later, to a bird who appears completely fine.
The one in the picture turned out fine but she was touch and go. When we found her the head was twisted around abut 270 degrees. We gently lifted her a placed her in the safety of the coop and she was fine in the morning.