A question that new or inexperienced backyard birders will often ask is “Where do birds sleep at night?” Surprisingly maybe, the answer is not that they sleep in their nests as many people think.
So Where Do Birds Sleep At Night?
The real answer is that it depends. A few factors come into play – the species of bird, the weather and also the number of predators that are in the area where the bird is. Most birds will sleep on the branches of trees or in shrubs. They usually prefer to be higher up so that they are safe from cats and other ground predators. Most birds will also not sleep on exposed branches, preferring to be hidden behind leaves and foliage. Heavy birds that are not very good at flying and are not capable of landing on tree branches usually sleep in dense foliage. This includes birds such as grouse and quail.
Ducks and geese and other birds with webbed feet are not able to sleep in trees because their feet do not allow them to perch. And they are not very quick at taking off so it is not safe for them to sleep on the ground as they cannot easily escape from ground predators. Birds such as these will sleep on the water, or on islands in the middle of the water.
Passerine birds have legs and feet that are specially designed for perching on branches, with one toe pointing backwards and the other three toes pointing forwards. They also have a tendon in the backs of their legs that tightens when their legs bend. This makes the toes curl and grip the perch. Because of this, they can sleep easily without falling off their perch. The great thing about this technique is that it does not take any work from the muscles for the birds to remain perched. Examples of passerine birds that sleep this way are cardinals, jays and sparrows.
A lot of birds will only sleep for very short periods at a time, always aware of the danger of predators. Many birds will even sleep with one eye open. They can effectively turn off one side of their brain while keeping the other side turned on. Each eye is linked to one side of the brain – to the opposite side, in fact. The left eye is linked to the right side of the brain and vice versa. So these birds can rest the right side of the brain and close the left eye while the right eye stays open and the left side of the brain stays alert.
This behavior can itself be turned on or off. So if a bird is on its own or with only a few other birds, it will use this skill to stay alert for predators. But when there is a large flock of birds, those in the middle of the flock will turn both sides of the brain off and go to sleep completely. Those birds on the outside of the flock will keep one eye open and only rest one side of the brain so that they can be on the lookout and warn the other birds about any predators. Swallows, crows and starlings are examples of birds that usually sleep in large flocks.
Of course the birds that are top of the predator chain, such as hawks and owls, do not have as much to worry about. They are pretty safe from predators as long as they sleep high up off the ground.