Can They Sleep While Flying, and How Does a Hummingbird That Never Lands Rest?
Constantly being on the move is quite exhausting. Therefore, birds, like other members of the animal kingdom, need to rest from time to time. But how do they do it?
When Birds Sleep
The method, time, and place of sleep differ among various species. For example, owls are nocturnal. They prefer to hunt in the dark and reserve the day for sleep. Although this doesn’t mean that owls can’t see anything during the day.
Most birds, on the contrary, are active during the day and rest at night. As a rule, they sleep when the sun sets and wake up when it rises.
Where Birds Sleep
Regardless of when they do it, all birds eventually fall asleep. They usually choose places protected from predators for this: trees, bushes, or small hollows.
Many birds sleep while sitting on a branch. How do they not fall? It’s simple: when the bird’s weight rests on its feet, the tendons tense up, forcing them to clench and grip the branch or perch. For instance, a bald eagle’s grip is ten times stronger than that of an adult human. Therefore, the likelihood of it slipping from its perch while dozing is low.
Hummingbirds actually sleep upside down. This is because they have thin and weak legs that are unable to support their body. However, they have long, sharp claws which they use to hold onto the branch during sleep.
Not all birds choose branches. Some sleep on buildings, others on the ground. Waterfowl, such as ducks and geese, sleep on the water or near it, sometimes standing on one leg, like flamingos and herons. And chimney swifts, during sleep, cling to vertical surfaces, such as chimneys.
How Birds Sleep
Sleeping for long periods is dangerous for birds, at least because of predators. As a rule, birds rest in short intervals and wake up often.
And in some birds, only one half of the brain rests during sleep, while the other remains active. The eye connected to the alert hemisphere stays open. This allows birds to monitor what is happening around them and rest at the same time.
Can Birds Sleep During Flight
The ability of birds to sleep by alternating one hemisphere of the brain and then the other allows some species to rest even during flight. And this is convenient. Indeed, swifts can remain in the air continuously for ten months straight. The record for the longest annual migration belongs to the Arctic tern. Migrating from the Arctic to the Antarctic, it covers approximately 70,000 km.
Great frigatebirds can sleep both on land and in the air. However, on land their sleep can last up to 12 hours a day, while in the air it’s only about 40 minutes. They also manage to sleep during flight through unihemispheric sleep. But why its duration is shorter in the air is something scientists have yet to figure out.
