Birds are very common in our daily lives, and the sparrows on the street, the magpies in the trees, the ducks in the river, and the parrots we keep are all birds. The chirping of sparrows, the geese flying overhead, the swallows we see by chance, they are all in our lives.
But even though we can see them every day, it seems that we have never been able to see what they are sleeping like. Will even wonder if the birds sleep? They either fly in the air or stand in trees, can they fall asleep while standing? Won't that fall?
In fact, birds do sleep, and studies have now shown that birds sleep similarly to humans, experiencing both REM sleep and non-REM sleep. So as the saying goes, "spring sleepy autumn lack summer napping, sleepless winter March", how do birds sleep? How do they sleep and how long do they sleep differently from us? Do birds really hibernate?
In addition to waterfowl such as ducks and swans, our common birds fly through the air and find a branch or wire to fall. In fact, they also need to stay on the tree to complete the sleep, so why don't they fall off the tree when they sleep?
We know that when birds stand on branches, they use their claws to hook the branches as support points to keep their bodies balanced. The same goes for sleep, their paws firmly grasp the branches and then fall asleep on them.
So the question is, when they sleep the body relaxes, won't the claws loosen? How to maintain balance when the claws are loosened. This brings us to the unique structure of the bird's hind limbs and claws:
Bird hind limb and claw structure
lap
Birds bend their knees in the opposite direction to humans, who move forward while birds are backwards. The joints known as "knees" are actually their heels, and the joints above them are their real knees. The upper thigh leg bone is attached, and together with the thigh, it is hidden under the feathers.
tendon
The bird's thigh muscles are directly connected to the tendons on the paws, and when the bird is standing on the tree, the thigh muscles relax, and the tendons stretch to withdraw the paws, so that the paws bend and tighten the branches. And when the thigh muscles are tense, the claws will open.
We can understand it this way, the bird relaxes the legs, the claws naturally retract, the birds tighten the muscles, and the claws open. So the more relaxed the bird grasps the branches, the tighter it grasps, that is, the deeper the bird sleeps, the tighter the claws.
Thanks to the unique structure of the birds' claws, they can naturally grasp the branches while sleeping without letting themselves fall.
In addition to standing on the branches, what other strange ways do birds sleep?
Float on the surface of the water. Birds represented: mallards, swans
One leg supports, tired to change the other. Birds represented: cranes, storks, herons
Turn a blind eye. Bird represented: owls
Form a circle with the head facing outward and the tail facing inward. Bird represented: partridge
Fly and sleep. Bird represented: albatross
However, we know that people cannot do such a thing in sleep, and only bats can hang upside down on trees in mammals. So why can birds sleep while making difficult moves?
Humans and other mammals go into a relatively unconscious state when they sleep, but birds are different, and birds can stay awake even in their sleep. This is due to the bird's sleep pattern – the hemispheric slow-wave sleep pattern, which we call usws.
Hemispheric slow-wave sleep mode, in which half of the brain is awake and half goes into deep sleep. It manifests itself with one eye open and one eye closed. When the left eye is open, it is the right brain that is awake; when the right eye is open, it is the left brain that is awake.
EEG during slow-wave sleep
Hemispheric slow-wave mode allows one hemisphere of the brain to enter deep sleep, and we know that the state of deep sleep can allow the brain to get effective rest and restore energy. Therefore, birds use alternating hemisphere slow-wave sleep to make up for the lack of sleep on the one hand, and to remain alert and cope with dangers on the other hand.
Usually, when the total amount of sleep in each hemisphere is added, the number of usws in both hemispheres is equal. Therefore, the sleep of birds also allows the two brain hemispheres to alternately rest, not only to let one hemisphere rest, or to prefer which hemisphere to rest.
This is why birds can turn a blind eye when they sleep, or alternately support sleep with one leg.
Waterfowl float on the surface of the water to sleep, because when the enemy is approaching, they can quickly feel and react through the vibration of the water surface. Partridge's head is surrounded in a circle that can detect whether there are any enemies in all directions. Birds like Swifts and Albatrosses, which fly in the air almost all day, allow them to sleep while flying, so that the brain can rest.
In addition to swifts, albatrosses, and birds on the way to migration, they also use this way to rest on the road. In addition, there is a phenomenon in birds that most birds do not return to the nest to sleep and rest after flying away from the nest. This may be because after the chicks are hatched, feathers, food scraps, feces, etc. accumulate in the nest, bacteria breed, or they are about to be dismantled by the chicks, so they are reluctant to go back to this place to sleep.
Since birds take the hemispheric slow-wave sleep method, when do they sleep? What is the difference between how long birds sleep?
Birds' sleep changes with the seasons. Under normal circumstances, most birds go to bed after dark and get up at dawn. There is a saying called "early birds have worms to eat", and the morning is the time when the birds begin to move.
But aren't there also owls among birds? "Night owls" sleep during the day and are active at night.
The gap between different birds' sleep time is also very large, most birds sleep about 8 hours a day, some birds sleep almost for a day, and some birds hardly sleep. For example, woodpeckers sleep about six hours, spotted sand ducks sleep thirteen hours a day, and Starlings sleep less than an hour a day.
We said earlier that birds can fly while performing hemispheric slow-wave sleep, because one hemispheric slow-wave sleep in birds is very short, only a few minutes. And after hemispheric slow-wave sleep there will be more brief REM sleep, only a few seconds.
Unlike humans, when birds sleep with RAPID EYE movements, their muscles are not completely relaxed, but maintain a certain amount of tension. So as long as the muscles can support the birds to spread their wings in the air, they can complete a RAPID eye movement sleep.
During the breeding season of birds, birds sleep much shorter, averaging two hours a day, and even no sleep for several consecutive days. Sandpipers breed in the Arctic Circle, and in the light of the day, they can stay awake for two weeks without sleep to incubate and prey on eggs. But the birds of this season can clearly observe emaciation and dull coat color, which are the consequences of lack of sleep.
What's even more amazing is that hibernation, which we usually think only happens to cold-blooded animals, actually happens to birds.
A small American partridge, people have observed for 4 consecutive winters, found that it will sleep every winter, the body temperature dropped from the usual 40 degrees Celsius to 20 degrees Celsius, curled up must not understand, with the earpiece can not hear the beating of the heart. This process can last for 88 days, and when spring arrives and the temperature rises, it starts to move again.
American nighthawks also hibernate, hibernating as if they were completely dead, barely feeling the heart or breathing, and irretrieving their pupils without any reaction.
In China, the phenomenon of bird hibernation has also been observed, and four Dai shengs have been found in the Loess Plateau, and they have inserted their mouths into the cloaca to sleep in a circle, motionless. In the Daxing'an Mountains in northeast China, forestry workers have found stiff hemp ducks in tree holes, and if the temperature gradually rises, the hemp ducks will slowly wake up.
hoopoe
In addition to hibernating, there are also birds that go into a brief "dormant" state due to food shortages and cold weather to conserve physical strength.
Sleep is an important way for birds to replenish their physical strength and restore their energy. According to the sleep habits of birds, we can change human activities accordingly. For example, reducing the lights in the bird habitat at night, setting up wooden boxes in the forest to help them avoid predators, etc., so that they can go to sleep with peace of mind, which is very conducive to their health.