I did a Google search and didn't see anything. But they must be in some sort of automatic mode because like in migration they can fly for days or weeks without landing.
Here is part of it .. pretty weird ...
"So to get a safe night's sleep, birds can close one eye and switch off one brain, and leave the other eye with the corresponding brain fully awake and alert. In fact, they can turn this on and off depending upon the circumstances. So in a large flock of geese roosting on a lake, the geese in the centre of the flock might have both brains asleep while the more vulnerable birds on the perimeter might have one eye open with its corresponding brain alert to look for predators. "
Yeah !!! I found it .. same article...
"But the majority of birds are perching birds from the order passeriformes ― sparrows, jays, warblers, cardinals and so. Around dusk, they find a branch, grab it with their clawed feet and squat down. These 'passerines' have special flexor tendons in their legs that automatically tighten onto the branch. So long as their legs are bent they are physically locked onto the branch ― and this action takes no muscular work at all."
Now i learned something today. Thanks for the question.
I think that's why they make nests, they may even sleep on roofs and other places not just trees.
They sleep in nests
For the same reasons why you don't die when you go to sleep .:-)
They're in their nests.
because of the law of rebel traps.
nests
tallent
