While birds can often be seen perched in a tree or nest during the day, they disappear at night. Unlike humans, who sleep deeply and are rarely aware of their surroundings, birds are always on the alert for predators in the dark. This is why they need to find a safe place to sleep for the night.
In the wild, a bird’s sleeping habits will vary depending on the species. Songbirds, like this Red-breasted Nuthatch, will find a sheltered spot where they can stay warm and away from nighttime predators. Waterfowl, like ducks and flamingos, roost on or in the water. Some birds, such as woodpeckers, cling to vertical tree trunks.
Other birds, such as swallows, owls and whip-poor-wills, will hunt at night. But most birds, including migratory species, are diurnal and will search out a good place to sleep at night.
Passerines, or perching birds, will seek out a sheltered spot to sit and relax. They will fluff up their feathers and tuck them close to their bodies in order to remain warm. These birds will often pull one leg up tight to their body, a position that also helps them stay balanced and stable on the perch.
For most species of birds, the best place to sleep is somewhere high up where they can keep an eye out for any potential predators. However, for some species, such as swifts, this is not possible and they sleep during their flight. This is a type of non-REM sleep called unihemispheric slow-wave sleep which allows them to maintain full awareness of their surroundings.