"But where and how do hawks sleep?" I asked John Bateman, and here is his fascinating reply:
"Good question. Where do hawks sleep? It’s a question every hawk watcher eventually asks. The answer is not so evident. Red-tails can be rather circumspect about the matter. They can seem to just evaporate towards dusk.
Red-tails, like most other birds, have an interesting and useful foot locking mechanism used when sleeping. As the bird begins to nod off, there is a ratchet-like band of tissue that can be tightened around the inside of the leg. Once tightened, it sticks together somewhat like velcro, locking the bird’s grip on the branch. The hawk doesn't have to pay any attention to holding on during the night. The bird’s toes are physically locked around the branch, and normal winds cause no problems.
That, then, raises the question of how well the hawks can see at night. From watching my several falconry red-tails over the years, it seems pretty evident to me that they can see at night just about as well as I can. That’s not too powerful. But I have some evidence that red-tails may be able, like rattlesnakes, see a bit down into the infrared spectrum. If that’s so, a distant red-tail taking an hourly peek at its distant nest and incubating mate at night may be able to easily seen a heat-emitting, thereby infrared-glowing raccoon ascending the nest tree in search of a nighttime hawk egg snack.