How and where do birds sleep?
(Cross-posted from Backyard Birder .) There's a really interesting piece in Slate.com today about the way that birds sleep. It seems that a lot of people have misconceptions about that. They think that birds sleep in their nests. But the sole purpose of nests is to provide a place to hold eggs and chicks, and once that purpose is fulfilled, that nest is so nasty that no self-respecting bird is going to want to sleep in it. The main concern of a bird looking for a bed for the night is to find a place that is safe from predators. A second concern may be to have some protection from the weather, but first and foremost is always the fear of predators. The predator problem is such a threat to birds' survival that they have evolved a brain that will help them to meet it. They are essentially able to sleep while one-half of their brain stays awake and alert for danger. This technique, called unihemispheric slow-wave sleep (USWS) allows the bird to have one hemisphere of their...