Where do hawks sleep?

Earlier this week, we had really severe thunderstorms in Philadelphia. I thought about the hawks in the midst of hail, high winds and lightning, and after the storms abated that night, hoped that they had found shelter and could sleep.

"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.

In fact, they can sleep in several kinds of perches. Out here in the Ohio countryside, on an evening when the hawks perceive that the night will be calm and rather windless, old haggards (adults) will commonly park themselves on the tops of tall utility poles and sleep the night out on this otherwise exposed perch. I have seen birds take such a perch at dusk, and saw them there the next morning at dawn.

But for years, the missing nights were a mystery. Where do the hawks sleep on windy, rainy nights, the ones where we’d like to be snuggled tightly under the covers, perhaps with our husband or wife? The answer has appeared recently by the diligent hawk watchers in Central Park following the exploits of Pale Male, the great red-tail that began the species’ urban incursion back in the 1990s. People in New York followed the bird closely, and were able to see him fly into trees and assume a night time, sleeping perch.

When they sleep, they turn their heads around and tuck them into the fluffed-up feathers of the back. I’ve quietly watched my sleeping falconry hawk with a dim flashlight. A sleeping hawk looks morbidly headless. I once had a wonderful red-tail that I took on my public lectures. She was so tame that on the way home at night she would sit on a perch I placed on the passenger seat of my car. Like a little child, the hawk would be fast asleep after driving just a mile or two at night. I’d look over there, and there she was–utterly without a head. It didn’t bother me. But when I stopped at a stop light and some trucker looked down into my car, the presentation was a bit eerie. I merely waved and moved on. That bird caused a lot of late night scratched heads.

It’s now pretty obvious that on rainy, windy, or otherwise unfavorable nights red-tails typically fly into a large hardwood tree, perch on a horizontal limb that allows the toes to wrap around the branch and grip it. But on a cold, windy, rainy, winter’s night, it would seem hard to be able to sleep in such a position. Here’s how it’s done.

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.

I’ve never encountered a sleeping red-tail in a gale. I think in those situations the bird must both lock its toes around the branch, and also stay awake and lean over into the wind. I don't know this, either, but I presume that the birds in these situations will attempt to park themselves in a somewhat protected position in the tree or woodlot. And this is why it would be so good to put a radio transmitter on a wild red-tail and find out just where the bird sleeps each night.

What about heavy rains? This is exactly why red-tails spend so much of their time diligently preening their feathers. As with all birds, they have the oil gland on their rump. The lean over and strop their bill on this gland, pick up some feather oil, and then preen it into all the feathers on the body. When well-preened, water runs off a hawk’s back almost as well as water off a duck’s back. Still, in the heaviest down pour, the outer feathers can get soaked. But the fluffy, inner down feathers remain oiled and water repellent. After a summer rainstorm we often seen a sodden red-tail. Underneath, though, she’s warm and dry. Red-tails, like all birds, are like turtles. They carry their houses of feathers with them wherever they go.

And except for the incubating mother, the parent hawks do not sleep in or on the nest. Hawk watchers should not regard the nest as a “home,” in any human sense. Yes, the birds stay near the nest, and often sleep within a hundred yards or so of it. But it’s not a place Mom and Pop try to go back to in any human manner. It’s important to understand that.

One other thing that was wonderfully discovered with Pale Male in NYC was that when he took his night perch, sometimes at some distance from the nest, he always seemed to maintain a straight, clear visual path to the nest. He could see the nest from where he slept. Even in thick branches there seemed to be always a clear view of the nest.

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.

For red-tails, this nighttime vision is still a bit sketchy and conjectural. That’s not the case, however, for peregrine falcons, who have remarkable nighttime vision capabilities. But that’s another (too lengthy) story to relate here.

–John Blakeman