Birds are absolutely incredible. They’re not only beautiful to look at and listen to – but they’re very hardy. Next time you go to your warm bed and it’s snowy, raining, or windy outside – just remember those amazing birds trying to catch some Z’s while perched on a tree branch exposed to the elements.
Bird sleep is a fascinating subject, so how do our feathered friends get some shut-eye?
Small birds sleep standing on perches close to tree trunks, or in shrubs and hedgerows. Waterfowl sleep floating on water, with wading birds perching on one leg in the shallows. Some species like woodpeckers sleep in tree cavities. Amazingly, some migratory birds can sleep whilst flying.
Let’s look at bird sleep in more detail, and consider how different types of birds sleep and where – plus how long they sleep for and when they wake up…
Where Do Birds Go To Sleep at Night?
Birds have adapted many ways to survive when the sun goes down, the temperature drops, and the night predators come out. Birds like to sleep in the tops of trees, in holes in trees, on the water or inside a thorny bush. Some even sleep in snow caves.
You may have guessed – wrongly – that birds like to sleep in the nests they build. Birds build nests to protect their eggs and then their chicks. But nests can get pretty messy and stinky – birds don’t like to use them to sleep in.
Small birds like to find high perches, usually near the main trunk of the tree in a niche, cavity, or roosting pocket. These spaces are called microhabitats. Microhabitats are small, unique areas within a larger habitat. For small birds, they must be warmer and safer.
Tree trunks can hold in some heat from the daytime. Not only is a spot next to the trunk warmer, but birds can feel the vibrations if a predator starts climbing up. Many birds will find a roost on the downwind side of the trunk.
By finding a safe spot amongst a dense group of branches, birds are protected from predators like owls, who will have a hard time swooping down on them. Birds are partial to evergreen trees or bushes, where the foliage is dense year-round.
Birds that live in open fields will find a scrubby, thorny shrub to sleep in. Some birds create snow caves for themselves and then huddle for warmth inside with other birds.
Waterfowl, like ducks and swans, like to sleep on the water. They can feel vibrations in the water caused by predators. Often, waterfowl will flock, a good survival tactic. When the flock senses a predator, they make a racket, alerting the rest of the flock and neighbor wading birds, too.
Many birds, like woodpeckers and bluebirds, prefer cavities in trees. If a woodpecker can’t find a hole, they’ll make one. Having a hole in a tree gives them lots of protection against predators and keeps them sheltered.
Nuthatches and other birds take advantage of the woodpecker’s old holes and move in, often in a large group, sometimes sleeping on top of each other.
Birds fluff up their feathers to help insulate their bodies, then tuck their head under a wing. By tucking their heads under their wing, their nostrils (or nares) breathe in air warmed by their bodies.
Birds have warm feathers, but what about their legs and feet? Birds have a remarkable counter-current circulation in their legs and feet. Birds are warm-blooded, except for their feet and legs, which are cold-blooded.
Do Birds Sleep Standing Up?
Yup. Birds can sleep standing up.
Not all birds sleep standing up. Some have safe holes in trees where they can relax and rest. Waterfowl sleep while floating. Wading birds sleep in shallow water with their head tucked under a wing while standing on one foot.
Some birds even sleep upside down. Their feet can cling to a branch all night long. Birds have highly developed flexor tendons, which cause the foot to curl up around a twig – and not let go.
Do Birds Sleep While Flying?
Yes! How cool is that?
Ornithologists have known for a long time that some birds fly for incredibly long periods of time, nonstop, like migratory birds and many oceanic birds. Scientists assumed that they just flew without sleeping. But a new study shows that some birds can sleep while they fly.
The study comes from the Max Planck Institute for Ornithology. They studied frigatebirds on the Galápagos Islands. Frigatebirds spend days flying nonstop over the ocean in search of food.
While the birds were on the island, the team attached tiny electroencephalography (EEG) devices to their heads. An EEG measures brain activity. When the birds took off for their 10-day flights, the EEG was recording. When the birds got back, the scientists collected their devices.
Like humans, birds have brains with two hemispheres. Unlike humans, birds can shut down one hemisphere at a time, allowing them to keep one eye open – literally – for dangers. This is called unihemispheric slow wave sleep, USWS (aka asymmetric slow-wave sleep).
Birds exhibit USWS as well as dolphins, seals, sea lions and whales. Scientists think that cetaceans (dolphins, whales) brains evolved to use USWS to allow them to surface for air while sleeping.
The frigatebird EEG data showed they used USWS on their 10-day flight. They didn’t use it too much – only for about 40 minutes on an average flight day.
The same Max Planck scientist, Neil Rattenborg, also did a study with mallard ducks. He studied four mallard ducks that were sleeping in a row. The outermost two ducks spent significantly more time in USWS than the ducks in the middle. The ducks in the middle of the row got more rest, while the outer ducks kept watch – with half their brains.
Scientists marvel at the resiliency of the bird brain. How can birds function for over a week with so little sleep? We humans are very dependent on sleep – can human brains be adapted to be more like bird brains?
Here’s an article about the study.
How Long Do Birds Sleep Each Day? (Or Night?)
It depends on the season. Birds are photosensitive. Their sleep cycle is tied to daylight’s seasonal changes. Their bodies react to the amount of daylight in other ways, too. In spring, for example, the amount of daylight triggers the breeding cycle.
Birds can be diurnal or nocturnal. Diurnal birds sleep when it gets dark and wake up when it gets light. Nocturnal birds are just the opposite – they sleep during the day and hunt at night.
Diurnal birds sleep mostly at night, although they may take power naps during the day. They settle down in their roosting spots when the sun goes down. There, they snooze for 12 to 13 hours, or longer during the winter months.
When Do Birds Wake Up?
Ahhh, the dawn chorus. Birders love it and night owls loathe it. Either way – you just can’t stop it.
In spring, the dawn chorus starts from 3 to 4 am and lasts for an hour or two. Dawn choristers are predominantly male.
Ornithologists have several theories about why birds pick the predawn hours to start the chorus. The predawn hours are very quiet. Predawn, the wind is low, and the temperature is cool. In the quiet, birdsong can be heard the farthest and the loudest.
By using their outside voices at this quiet time, male birds hope to attract mates.
Birdsong is amazing. Nightingales have a repertoire of around 300 love songs. The brown thrasher has over 2,000 different songs. The cowbird uses over 40 different notes, some too high for a human to hear. In spring, a male bird can repeat his love song over 500,000 times.
Did you know that, slowed down, some bird songs have parallels with Beethoven’s symphonies, specifically Beethoven’s Fifth?
The dawn chorus for male birds is also about staking out territory. Male birds need to have a territory to attract a female. Territorial songs are shorter and simpler than love songs.
Another theory about the dawn chorus is that, in the predawn hours, most predators are snoozing. It’s a safe time to be noisy.
Other scientists think that male birds like the predawn time because it’s too early to find food. Many birds are foragers. They eat insects, worms and larvae. These food sources don’t come out until the sun starts warming the earth. So – the foragers might as well sing.
Here’s a fascinating article about birdsong.
Our family love watching the birds in our garden, and listening to them chirping and singing. We’re also all in awe of how durable they are when it comes to sleeping outside at night in any weather.
Discovering more about the finer details of bird sleep has been fascinating, and has made me appreciate our feathered friends in the yard even more than ever.
With that said I’m going to step away from the screen for a while and go and put some food out for them in the bird feeder. 🙂