Most of the birds around us are diurnal which means they are active during the day. Although you may hear the odd bird singing at night most birds seem to disappear so where do they go to sleep?
When birds are asleep they are at their most vulnerable to predators, so they have to choose carefully where they spend the night. They will tend to roost in large flocks in dense foliage in trees and shrubs, or find a cavity in a building, a hole in a tree or a nest box to sleep in.
Passerines, or perching birds, will find somewhere to perch, fluff up their feathers, tuck their beaks into their back feathers and often pull up one leg close to its body before falling asleep. Although this sounds like it could be an uncomfortable position to get some shut-eye, it helps the bird keep warm and conserve energy during the night. By pushing the weight of their body down onto its leg muscles, the tendons of the feet will tighten, gripping the perch so they don’t fall off.
Waterfowl and wading birds, will sleep near or even on water. They tend to sleep in large flocks giving them protection and any movement on the water will alert them to predators nearby.
Swifts and frigate birds which spend almost all their life in the air, sleep on the wing. A study in 2016 showed that most of the time half of their brain is asleep although they also go into whole-brain and deeper REM sleep which lasts just a few seconds; the equivalent of a power-nap.
