The Cooper's and Sharp-Shinned hawks we had in the Eugene, Oregon area where I grew up would lurk in the trees all day, waiting for the opportunity to snag an unwary pullet. Once the hens reached full size, the mental image in the minds of the predators didn't keep up to speed, and we witnessed three episodes where a small hawk landed on the back of a big Buff or Orp, talons firmly fixed in the feathers while the hens squawked.
The small hawks flapped vigorously, didn't achieve liftoff, stopped to reposition their talons, flapped again, thought about it -- and finally flew away.
We were lucky they wanted the whole meal TO GO and didn't start ripping off pieces while they were trying to figure it out! By the time we got out to the hens being victimized, they responded to being picked up and cooed to, especially when offered a treat, so no lasting damage occurred (except to their dignity).
We found that having several "hides" made of plywood in the yard provided an escape route, especially when the roosters sounded their warnings and everybody scattered as the hawks made their dives. Of course, the optimal (but most expensive) answer is to cover the run.