Nature uses many mechanisms to protect plants and animals from the harmful effects of external factors and dangers. Speed, strength, sharp teeth, poison are all active means of survival. Camouflage, symbiosis and suspended animation are passive methods that help to survive. The article will tell about the hibernation of bears, answer questions about how bears prepare for winter, when bears go to sleep when they wake up.

What is hibernation

Hibernation is a time of slowing down of life processes and chemical metabolism in the body of warm-blooded animals. The main characteristics of this condition are: a decrease in body temperature by several degrees, breathing becomes rare, slowing of the heartbeat, and inhibition of physiological processes. Hibernation is used by animals for self-preservation during periods when it is difficult to find food, when extreme cold sets in. The condition can last from a few days to many months.

What animals can hibernate

Since childhood, everyone knows that in winter it hibernates, during which it sucks its paw, and wakes up only in spring. And the answer to the question of when bears hibernate is known even to children - in late autumn.

In fact, bears do not go into true hibernation, which is essentially a suspended animation of the body. They only fall into a light sleep, waking up easily when disturbed. During this sleep, the body temperature of the bears drops to 31 ° C, while the normal temperature of the animal is approximately 38 ° C. For comparison: the body temperature of the American ground squirrel, which is 38 ° C in the active state, drops to zero during hibernation! Still, Toptygin's body works in economy mode, the number of heartbeats decreases to ten per minute, metabolic processes slow down several times.

How a clumsy bear prepares for hibernation. Fat accumulation

In order to successfully overwinter, you need to solve two questions:

• accumulate energy reserves;
• prepare a room for wintering - a lair.

Energy reserves are fat. To accumulate it, the bear spends the whole summer in active search food. He loves sweet forest berries, especially raspberries and strawberries, but he is picky in food and eats roots, ants, fish, and small mammals. The underskin layer of fat in bears closer to cold weather reaches a thickness of 7-9 cm. Females gain weight up to 150 kg or more, males - up to 300 kg, with 1/3 of the total mass falling on fat.

A few days before leaving for the winter, they stop eating and actively empty their intestines. After all, when bears go into hibernation, they do not eat for six months, do not drink water and do not defecate.

Preparing the lair for wintering

The second thing is to prepare a shelter - warm enough to shelter from the frost, and safe enough not to become easy prey for the enemy.

The bear chooses a place for a future den very carefully. Depending on the species, this may be a depression between tree roots, a cave or a rocky niche, an abandoned anthill, a tree hollow. Sometimes bears dig dugouts, strengthening the walls with boughs, very rarely they build riding dens - a structure made of branches on the ground, resembling a large bird's nest.

The bottom of the rooming house is covered with spruce branches, peat, moss, dry leaves, hay, and when bears go to sleep, they are warm and comfortable in their bed.

The dimensions of the den are not much larger than the body of the animal. Toptygin always leaves a hole through which air enters his shelter. Surprisingly, the snow, completely falling asleep in the den, never falls asleep in the "window", so successfully the bear knows how to choose a place for it.

What month does a bear hibernate?

Scientists have long been studying this natural phenomenon like hibernation. Much attention is paid to physiological processes such as metabolism and changes in metabolic reactions. Scientists are also interested in when bears hibernate. In Siberia and in Europe this happens at different times. The following factors matter:

• gender, age and physiological state of the animal;
• yield of bear feed;
• natural area;
• weather.

Pregnant females and mothers with cubs are the first to leave for the winter in early November. Barren she-bears and males at the end of November, and in the southern regions they can last until mid-December.

In years with a particularly large harvest of nuts, acorns, these dates are shifted by a few more weeks closer to winter.

If for some reason the bear did not have time to work up fat for the winter or arrange a dwelling for himself, then he does not hibernate. Such animals are called rods. They are very dangerous because they behave aggressively and viciously.

Now the reader knows what time the bear goes to sleep and how he prepares for it. It remains to be clarified that Toptygin leaves the lair in the south already at the end of February, in the middle latitudes - in March, in the north - in April. Thus, wintering can last from 2.5 to 6 months.

For those who have wings, it's good - they flew away and that's it. well and brown bear through bowls and wild forest do not get to places where the climate is warmer.

And he finds a pretty practical solution. In the summer, the bear eats off, then to hibernate until the very spring. But not everything is as simple as it might seem at first glance. Imagine what you would look like if you didn’t drink and eat for six months. Let's get acquainted with some of the amazing processes that occur in the body of a bear during hibernation.

busy summer

To prepare for the semi-annual "fasting", the she-bear needs to make energy reserves. So she doesn't worry about her figure. Its main goal is to accumulate more subcutaneous fat (in some places its thickness reaches eight centimeters). Although she likes sweet berries most of all, she is not a picky eater. She eats everything: roots, small mammals, fish and ants. By autumn, she can gain weight up to 130-160 kilograms, a third of which is fat. (The weight of a male can reach up to 300 kilograms.) Before plunging into the world of dreams, she stops eating and frees her intestines. For the next six months, she does not eat anything, does not urinate or defecate.

Bears choose a place for a den in a cave, an abandoned anthill or a depression under the roots of trees. The main thing is that it was quiet there and no one disturbed the sweet dream. Bears collect spruce branches, moss, peat and other materials to make a warm and cozy bed. The lair is not much larger than the massive body of a bear. When winter will come, snow will cover the lair and only an attentive observer will be able to see the hole through which air enters there.

hibernation

Some small mammals, such as hedgehogs, the bats and dormouse, fall into the real hibernation, that is, they spend most of the winter in a state similar to death. Their body temperature is approaching the temperature environment. But the bear's body temperature drops only 5 degrees Celsius, so his sleep is not that deep. "You can't say that a bear 'sleeps without its hind legs'. A bear raises its head and rolls from side to side almost every day," says Raimo Hissa, a professor at the University of Oulu in Finland, who has devoted many years to studying bear hibernation. Yet the bear rarely goes out from her lair in the middle of winter. During hibernation, the animal's body works "in economy mode. The heart rate drops to 10 beats per minute, and the metabolic process slows down. When the bear sleeps sweetly, fats begin to be burned in her body. Fatty tissues are broken down by enzymes and supply the animal's body with the calories and water it needs.Even though the life-sustaining processes in the body are slowing down, a certain amount of waste is produced as a result of metabolism.How can a bear get rid of them and still keep her den clean?Instead of removing waste the body processes them!

Professor Hissa explains: "Urea from the kidneys and bladder is reabsorbed into the bloodstream and transported by the circulatory system to the intestines, where it is hydrolyzed by bacteria into ammonia." Even more surprising is that this ammonia goes back to the liver, where it is involved in the formation of new amino acids that form the basis of proteins. By converting waste products into building materials, the bear's body feeds itself during the long hibernation period!

In the old days, people hunted bears sleeping in dens. Sleepy Toptygin became easy prey. First, hunters on skis found a lair, then surrounded it. After that, the bear was awakened and killed. Today, winter bear hunting is considered cruel and banned in most of Europe.

Studying hibernation of bears

The department of zoology at the University of Oulu has been researching the physiological processes by which animals adapt to the cold for several years. Brown bears began to be studied in 1988, and a total of 20 individuals were observed over the years. A special lair was created for them in the zoological garden of the university. To measure body temperature, study metabolism, vital activity, as well as changes that occur during hibernation in the blood and hormones, scientists used computers, video cameras, and did laboratory tests. Biologists collaborated with specialists from other universities, even Japanese ones. They hope that the results of the research will be useful for solving problems related to human psychology.

New life

The bear sleeps all winter, turning from side to side, but an important event takes place in the life of the bear. Bears mate in early summer, but the fertilized cells inside the body of the expectant mother do not develop until the bear goes into hibernation. Then the embryos attach to the wall of the uterus and begin to grow. After only two months (in December or January), the body temperature of the expectant mother rises slightly, and she gives birth to two or three cubs. After that, her body temperature drops again, although it does not become as low as before childbirth. Daddy bear does not see how his children are born. But the sight of newborns would probably disappoint him. It would be difficult for a huge dad to recognize these tiny creatures weighing less than 350 grams as his offspring.

The mother bear feeds her cubs with nutritious milk, this depletes her already weakened vitality. The cubs grow quickly, by spring they become fluffy and already weigh about five kilograms. And this means that in the small "apartment" of the she-bear there is a revival.

Spring

March. Cold winter has passed, the snow is melting, the birds are returning from the south. At the end of the month, male bears crawl out of their lairs. But the female bears remain in their hiding place for several more weeks, perhaps because the cubs take a lot of strength from them.

After a long hibernation, a well-fed bear leaves skin and bones. The snow melted, and her fat melted with it. For all that, the she-bear is surprisingly mobile - no bedsores, cramps or osteoporosis. Some time after leaving the lair, she cleans the intestines. Bears usually start eating only two or three weeks after waking up, as the body does not immediately get used to the new conditions. But then they wake up remarkable appetite. But since nature itself has recently awakened from its winter sleep, at first there is not much food in the forest. Bears chew grubs and bugs, eat old corpses, and sometimes even hunt reindeer.

The care of raising cubs falls on the shoulders of the she-bear, and she protects her cubs like the apple of her eye. An ancient proverb says: “It is better for a man to meet a she-bear without children than a fool with his foolishness” (Proverbs 17:12). In other words, it is better not to meet with either one or the other. “A mother bear has a lot to worry about. If a male bear approaches, she immediately forces the cubs to climb the tree. The point is that the male can harm them even if he is their father,” Hissa explains.

The cubs spend another winter in the den with their mother. Well, next year they have to look for their own lair, as the she-bear will have new tiny babies.

We already know a lot about the complex and unusual phenomenon of hibernation in bears, but much remains a mystery. For example, why does a bear get sleepy in autumn and why does he lose his appetite? Why doesn't he get osteoporosis? Revealing bearish secrets is not easy, and understandably so. Everyone has their own secrets!

Next of kin brown bear. They originated from common ancestors, who lived only 150 thousand years ago (for the evolution of species, this is quite recent). The brown bear perfectly hibernates in the winter, and can the polar bear sleep in the den in the summer?

And in general, if the dens polar bear?

Surprisingly, almost no sleep! That is, they sleep normally, just like in summer (only in summer they usually sleep more). But they do not fall into winter sleep. (“Hibernation” of bears is more correctly called winter sleep; bears do not have real hibernation, since their body temperature almost does not drop, and at any moment they can wake up.) Only pregnant and nursing females fall into winter sleep. The rest of the polar bears, if they lie in dens, then not for long and not every year.

The main food of polar bears is seals. These are such seals. They are hunted by polar bears on the ice. They either snatch the seal with their paw from the hole in the ice through which the seal breathes, or lie in wait and grab the seals that have climbed out onto the ice to rest. In many areas of the Arctic where polar bears live, the ice almost completely melts by the end of summer. They can no longer hunt seals. On land, most arctic animals are able to run away from a polar bear, and in the sea they can swim away from it. It is good if you manage to find the carcass of a dead whale or walrus on the shore. And if not, then at the end of summer and autumn, bears sometimes go hungry for several months. So in winter they do not sleep, but start hunting again as soon as the ice appears.

But the females have nowhere to go - they have to lie in dens. After all, polar bear cubs, like other bears, are born small (their mass is less than a kilogram) and blind; they are covered only with short down. Usually females arrange a lair on the shore, sometimes 50 km from the seashore. As a rule, a she-bear makes a lair in a snow dune, but if there is little snow, she can also dig a hole in frozen ground. The female lies in the den just when the ice melts and it becomes difficult to hunt. Bear cubs are usually born in November-January, and remain in the den until February-March. Before the birth of the cubs, the mother bear does mostly sleep, but during the birth she wakes up, and after the birth she has to sleep less. However, she is still in a state of winter sleep before leaving the den: she does not eat, drink, pee or poop.

How does the female manage to accumulate nutrients for a long sleep and for feeding cubs (and there are usually two of them)? It turns out that polar bears mate in the spring - in April-May. Immediately after mating, pregnant females begin to eat so intensely that by autumn they become 200 kg heavier - their weight sometimes almost doubles! At the same time, the development of embryos in the abdomen of a bear in the spring stops at early stage and continues only in autumn; before that, they are at rest (scientifically called embryonic diapause). Apparently, this allows female bears to "adjust" the beginning of embryo development to the time of entry into the den; after all, this time depends greatly on the conditions in a given area and even on the weather in a given year.

It is not very clear why all the polar bears should not eat too much. But for some reason they don't.

It is interesting that, apparently, at any time of the year, during prolonged starvation, polar bears seem to “sleep on the go.” In their blood, the concentration of urea drops sharply, which is typical for other types of bears during hibernation. Bears are able to use urea for the synthesis of amino acids and proteins of the plasma (liquid part) of the blood. (Plasma protein concentrations should be kept as constant as possible, otherwise there are various problems with fluid transport and metabolism in the body.) In addition, the lower the urea content, the less it needs to be excreted in the urine, which means less need to drink. Although water in the form of snow is usually readily available in the Arctic, drinking (or rather, eating) it is energetically unprofitable - a lot of energy is wasted on warming it.

If a brown bear's urea concentration has dropped, it becomes lethargic, no longer wants to eat, and falls asleep. But the polar bear, in the presence of food, begins to eat again and raises the concentration of urea to a normal level.

Interestingly, during the period of winter sleep, the polar bear somehow manages to almost not lose bone and muscle mass. Usually, in humans and other animals, their mass decreases sharply with prolonged immobility, even when there is food; the mass of bones and muscles also decreases in other species of bears during sleep. But the polar bear consumes almost only fat. It turns out that in some respects, polar bears are more adapted to winter sleep.

sources

On average, a bear's hibernation takes about five months (or 150 days), but the duration can vary. Bears wake up when their fat reserves are depleted or the climate changes - the sun is actively warming, and the snow is melting. In some regions, animals can sleep much less - only three months. And in the Caucasus, they do not hibernate at all, since there all year round the available food does not run out. The longest wintering is observed in Alaska. Here bears can sleep for seven months in a row.

What conditions are needed for sleep

In the spring and summer, clubfoot actively fatten up fat so that their body, which is in sleep mode, receives the necessary nutrients. In autumn, the bear finds a comfortable place and equips it, warming it with grass and moss. The lair can be located under big tree or in the bed of an empty anthill. After that, the beast settles down comfortably and switches to sleep mode.

The place for wintering should be dry and comfortable for lying, otherwise the bear may wake up without waiting for the end winter period. In nature, there are cases when a bear got up and began to look for another den, more comfortable. If you can't find appropriate place, the poor guy is just wandering around the neighborhood, half asleep. From this came the name of the connecting rod bear.

Bear dream - sensitive

Scientists believe that a bear's dream cannot be called a full-fledged hibernation. These animals sleep quite sensitively in order to be able to protect themselves from possible attacks. It has been noted that there is no uninterrupted sleep in clubfoot. They can periodically get out of the den to check if everything is calm.

Physiologically, this period proceeds a little differently than in other hibernating animals. Life processes in the body of a bear do not slow down significantly, but only slightly decrease. Temperature regime changes by only five degrees. For comparison, gophers sleep soundly for eight months, and their body temperature drops as much as -2 degrees. Therefore, bears are sensitive to sounds and can easily wake up.

A mother bear takes care of her cubs during hibernation. She periodically turns over, warming and protecting the kids. In a sleepy state, even the process of feeding takes place. Thus, the offspring are reliably protected and fed until the very awakening of the mother. By spring, the bear's resources are severely depleted. Therefore, after waking up, she immediately begins to replenish her fat reserves.

Did the kids ask you the question - Why do bears hibernate?

🙄They are probably very interested in why the bear sleeps in his lair all winter? Here is your answer...

👉This type of mammal belongs to animals with large dimensions. To feed themselves, they need a lot of food. These predators are omnivorous, but some people prefer animal food, some - vegetable food🌱🍓 In the cold season, it becomes difficult to get a second one🌱🍓, and it is difficult for bears to survive for a long time only on eating other living creatures. The inability to eat properly leads to the fact that they hibernate😴

From a scientific point of view, a bear's hibernation is not a complete sleep. When an animal lies in a den, its metabolic processes slow down. At the slightest danger, the animal quickly wakes up. The bear's body temperature drops by only a few degrees - from 38 to 31-34. The state of sleep is preceded by the appearance of lethargy, slowing down of movement, and apathy in predators. This, on an instinctive level, makes you look for a place to build a lair.

👉 During hibernation, the bear does not defecate or urinate: waste products are processed into proteins, so necessary for its existence. The body is completely rebuilt to a new mode.