Medieval firearms. Bladed weapons of medieval Europe
It's no secret that Siberian winter- a difficult test for many animals, and bears are no exception.
In common parlance they say that a bear hibernates; biologists say that it goes into winter sleep. Details about this most interesting process A little. main reason lies in the difficulty of collecting data.
The brown bear is found everywhere in the reserve, both in all types of forests and in the mountain-tundra belt. On the territory of the reserve it makes seasonal movements from forests to the high mountain zone and back, often using trails and country roads for migrations.
What does a bear eat before hibernation?
Before going into a den, the owner of the taiga needs to accumulate nutrients. The bear is an omnivore, but most his diet in Kuznetsk Alatau, as in many other places, consists of feed plant origin: berries, herbaceous plants, acorns, nuts.
Cedar cones- one of the favorite delicacies of bears and one of the best fattening foods. Young animals can climb trees behind them and break off branches. But mostly they collect fallen cones from the ground. To get to the nuts, the bear collects the pine cones in a pile and crushes them with its paws, from where it then, lying on the ground, picks out the nuts along with the shell with its tongue. The shells are partially discarded during the meal and partially eaten.
Often the attention of bears is attracted by the stocks of nuts made by chipmunks. By digging up the animals' burrows, bears get to the nuts and eat them, often together with the owner. They do not miss the opportunity to feast on ant larvae, bird eggs or fish; they also hunt small rodents and ungulates. A brown bear rarely kills wild ungulates itself; it mainly devours them as carrion or takes the prey of other predators (wolves, lynxes, wolverines).
There are known facts of predators eating such species of wild ungulates as elk, deer, and roe deer. He covers the prey or found carrion with brushwood and stays nearby until he finishes the carcass completely. If the animal is not very hungry, it often waits several days until the meat becomes softer.
It is very important how productive the year was for fattening feed. Lean years can greatly delay the time for bears to go to dens, and animals can continue to feed even in twenty-degree frosts and almost half a meter of snow cover, digging out cones from under the snow, trying to gain the fat reserves necessary for wintering. In years favorable for food, adult bears accumulate a layer of subcutaneous fat up to 8-12 cm, and the weight of fat reserves reaches 40% of the total weight of the animal. It is this fat accumulated over the summer and autumn that the bear’s body feeds on in the winter, surviving the harsh winter period with the least deprivation.
Hungry years lead to the appearance of connecting rod bears
These are animals that have not had time to gain sufficient fat reserves, which is why they cannot hibernate. Connecting rods, as a rule, are doomed to death from hunger and frost or from a hunter. But not every bear encountered in the forest in winter will be a crank. During “after-hours,” bears appear in the forest, whose sleep in their den is disturbed. A normally well-fed bear, but torn out of hibernation, is forced to look for a new, quieter place to sleep. Animal sleep is often interrupted by human disturbance.
Bear's den
Before heading to the den, the bear diligently confuses its tracks: it meanders, walks through windbreaks, and even walks backwards along its own tracks. For dens, they usually choose remote and reliable places. They are often located at the edges impassable swamps, along the banks of forest lakes and rivers, in windbreaks and in logging areas. The brown bear makes its winter home in depressions under uprooted roots or tree trunks, sometimes on a pile of brushwood or near an old woodpile. Less often he chooses a cave for his home or digs deep earthen burrows- ground dens. The main condition is that the home should be dry, quiet and isolated from the presence of unexpected guests. One of the signs of the proximity of a den is large bald spots in the moss, gnawed or broken trees. The animal insulates its shelter with branches and lines the bedding with layers of moss. Sometimes the layer of litter reaches half a meter. It happens that several generations of bears use the same den.
At the beginning of winter, female bears give birth to offspring
From one to four cubs are born, but more often two. Babies are born blind, without fur and teeth. They weigh only half a kilogram and barely reach 25 cm in length. It is interesting that the nipples of female bears are not located along the line of the abdomen, as in most animals, but in the very warm places: in the armpits and inguinal cavities. The cubs feed on 20 percent fat milk from their still sleeping mother and grow quickly. Within a few months of such feeding, the cubs are completely transformed, and they emerge from the den already shaggy and nimble. True, they are still very dependent.
How a bear sleeps in a den
In the den, in warmth and safety, bears sleep throughout the long and cold winter. Often the bear sleeps on its side, curled up in a ball, sometimes on its back, less often it sits with its head lowered between its paws. If an animal is disturbed while sleeping, it easily awakens. Often the bear itself leaves the den during prolonged thaws, returning to it at the slightest cold snap.
Animals hibernating (for example, hedgehogs, chipmunks, etc.) become numb, their body temperature drops sharply, and, although vital activity continues, its signs are almost invisible. In a bear, the body temperature decreases slightly, by only 3-5 degrees and fluctuates between 29 and 34 degrees. The heart beats rhythmically, although slower than usual, and breathing becomes somewhat less frequent. The animal does not urinate or defecate. Any other animal in this case would have experienced fatal poisoning, and the bears begin a unique process for recycling waste products into useful proteins. A dense plug forms in the rectum, which some people call a “plug.” The predator loses it as soon as it leaves the den. The cork consists of tightly compressed dry grass, the fur of the bear itself, ants, pieces of resin and pine needles.
Brown bears They sleep alone, and only females who have young yearlings sleep together with their cubs. The duration of hibernation depends on weather conditions, health and age of the animal. But usually this is the period from the second half of November to the first half of April.
Why does a bear suck its paw?
There is a funny opinion that a bear sucks its paw during hibernation. But in fact, in January, February it happens change of hard skin on the paw pads, wherein old leather bursts, peels, and itches very much, and in order to somehow reduce these unpleasant sensations animal licks its paws.
It took more than one thousand years natural selection so that such a a complex system adaptations as a result of which bears acquired the ability to survive in areas with harsh climatic conditions. One can only marvel at the diversity and wisdom of nature.
Previously on the topic Bears:
Do polar bears hibernate? April 14th, 2018
And what - the closest relative of the brown bear. They descended from common ancestors who lived only 150 thousand years ago (this is very recent for the evolution of species). A brown bear hibernates well in winter, but can a polar bear sleep in a den in the summer?
And in general, if there are dens polar bear?
Surprisingly, they barely sleep! That is, they sleep normally, just like in the summer (only in the 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 hardly drops, and they can wake up at any moment.) Only females who are pregnant and nursing newborn cubs fall into winter sleep. The rest of the polar bears, if they lie in dens, do so only for a short time and not every year.
The main food of polar bears is seals. These are such seals. Polar bears hunt them on the ice. They either snatch the seal with their paw from a hole in the ice through which the seal is breathing, or they lie in wait and grab 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 outrun a polar bear, and in the sea, they can swim away from it. It's good if you can find the carcass dead whale or a walrus on the shore. And if not, then at the end of summer and autumn the bears sometimes starve for several months. So in winter they do not sleep, but start hunting again as soon as ice appears.
But the females have nowhere to go - they have to lie down in dens. After all, polar bear cubs, like other bears, are born small (their weight is less than a kilogram) and blind; they are covered only with short fluff. Usually females make a den on the shore, sometimes 50 km from the seashore. As a rule, a bear makes a den in a snow dune, but if there is not enough snow, she can dig a hole in frozen ground. The female lies down in a den just when the ice melts and hunting becomes difficult. Cubs are usually born in November-January, and remain in the den until February-March. Before the birth of the cubs, the mother bear actually sleeps mostly, but during childbirth she wakes up, and after giving birth she has to sleep less. However, before leaving the den, she is still in a state of winter sleep: she does not eat, does not drink, does not pee or poop.
How does the female manage to accumulate nutrients for a long sleep and for feeding her 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 feed 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 female bear’s abdomen stops at an early stage in the spring and continues only in the fall; Before this, they are in a state of rest (this is scientifically called embryonic diapause). Apparently, this allows female bears to “adjust” the onset of embryo development to the time they enter the den; after all, this time greatly depends on the conditions in a given area and even on the weather in a given year.
It’s not very clear why all polar bears shouldn’t eat their fill in the same way. But for some reason they don't do this.
It is interesting that, apparently, at any time of the year, during prolonged fasting, polar bears seem to “sleep on the move.” The concentration of urea in their blood drops sharply, which is typical for other species of bears during hibernation. Bears are able to use urea to synthesize amino acids and proteins in the plasma (liquid part) of the blood. (The concentration of proteins in plasma should be as constant as possible, otherwise various problems with fluid transport and metabolism in the body arise.) In addition, the lower the urea content, the less it needs to be excreted in the urine, which means the less you 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 lost to warm it.
If a brown bear's urea concentration has decreased, it becomes lethargic, no longer wants to eat, and falls asleep. But if food is available, the polar bear begins to eat again and raises the urea concentration to normal levels.
It is interesting that during the period of winter sleep, the polar bear somehow manages to lose almost no mass of bones and muscles. Usually in humans and other animals their weight 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 uses almost only fat. It turns out that in some respects polar bears are better adapted to winter sleep.
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It’s good for those who have wings - they flew away and that’s it. well and brown bear through the thickets and wild forest can’t get to places where the climate is warmer.
And he finds a rather practical solution. In the summer, the bear eats its food and then goes into hibernation until spring. But not everything is as simple as it might seem at first glance. Imagine what you would be like if you didn’t drink or eat for six months. Let's get acquainted with some amazing processes that occur in the body of a bear during hibernation.
Busy summer
To prepare for the six-month “fast,” the she-bear needs to make energy reserves.” So she doesn't worry about her figure. Her main goal is to accumulate more subcutaneous fat(in some places its thickness reaches eight centimeters). Although she likes sweet berries best, she is not picky about food. 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 male can weigh up to 300 kilograms.) Before plunging into the world of dreams, she stops eating and emptys 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 is quiet there and no one disturbs your sweet sleep. Bears collect spruce branches, moss, peat and other materials to make a warm and cozy bed. The den is not much larger than the massive body of the bear. When winter comes, snow will cover the den 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 sleepyheads fall into the present hibernation, that is, they spend most of the winter in a state similar to death. Their body temperature approaches the temperature environment. But a bear's body temperature only drops by 5 degrees Celsius, so its sleep is not that deep. “It cannot be said that the bear “sleeps without hind legs"The bear raises its head and turns from side to side almost every day," says Raimo Hissa, a professor at the University of Oulu in Finland, who has spent many years studying bear hibernation. Yet the bear rarely leaves its den in the middle of winter. During hibernation, the body The animal works “in economy mode.” The heart rate decreases to 10 per minute, and the metabolic process slows down. When the bear sleeps, fats begin to be burned in her body. Adipose tissue are broken down by enzymes and supply the animal’s body with the necessary calories and water. Even though the processes that support life in the body slow down, a certain amount of waste is produced as a result of metabolism. How can a mother bear get rid of them and at the same time keep her den clean? Instead of removing waste, the body processes it!
Professor Hissa explains: “Urea from the kidneys and Bladder reabsorbed into the blood and transported circulatory system into the intestines, where it is hydrolyzed by bacteria into ammonia.” Even more surprising is that this ammonia goes back to the liver, where it participates in the formation of new amino acids that form the basis of proteins. Converting waste products into Construction Materials, the bear's body feeds itself during a long period of hibernation!
In the old days, people hunted bears sleeping in dens. Sleepy Toptygin became easy prey. First, hunters on skis found a den, then surrounded it. After this, the bear was woken up and killed. Today winter hunting Bear hunting is considered a cruel activity and is banned almost throughout Europe.
Studying bear hibernation
The Department of Zoology at the University of Oulu has been conducting research for several years on the physiological processes by which animals adapt to cold. Brown bears began to be studied in 1988, and a total of 20 individuals were observed over these years. A special den was created for them in zoological garden university. For measuring body temperature, studying 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 research results will be useful for solving problems related to human psychology.
New life
The bear sleeps all winter, turning over from side to side, but what happens in the life of the bear is an important event. Bears mate in early summer, but the fertilized cells inside the expectant mother's body do not develop until the mother hibernates. The embryos then attach to the wall of the uterus and begin to grow. After just two months (in December or January), the body temperature is expectant mother rises a little, and she gives birth to two or three cubs. After this, her body temperature drops again, although it does not become as low as before childbirth. Papa Bear does not see his children being 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 she-bear feeds the 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. This means that the bear’s small “apartment” is full of excitement.
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 emerge from their dens. But the mother bears remain in their shelter for several more weeks, perhaps because the babies take a lot of their energy.
After a long hibernation, all that remains of a well-fed bear is skin and bones. The snow melted, and with it her fat melted. With all this, the bear is surprisingly mobile - no bedsores, seizures or osteoporosis. Some time after leaving the den, she cleanses the intestines. Typically, bears begin to eat only two or three weeks after waking up, since the body does not immediately get used to the new conditions. But then they develop a remarkable appetite. But since nature itself has recently awakened from winter sleep, at first there is not much food in the forest. Bears chew larvae and beetles, eat old carcasses, and sometimes even hunt reindeer.
The care of raising cubs falls on the shoulders of the mother 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 mother bear without children than a fool with his foolishness” (Proverbs 17:12). In other words, it is better not to date either one or the other. “Mama bear has a lot on her plate. If a male bear approaches, she immediately forces the cubs to climb a 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, on next year they have to look for their own den, since the mother bear will have new tiny cubs.
We already know a lot about the complex and unusual phenomenon of bear hibernation, but much still remains a mystery. For example, why does a bear become sleepy in the fall and why does it lose its appetite? Why doesn't he have osteoporosis? Uncovering a bear's secrets is not easy, and that's understandable. Everyone has their own secrets!
Some animals such as bears, hedgehogs, frogs, badgers, moles, reptiles in winter time years old need a lot of sleep. This kind of sleep is called hibernation, and it can last for several months. . So why do bears and other animals hibernate in winter?
Sleep is protection from the cold, long winter . Having fallen into hibernation, the animal’s body is completely rebuilt. Breathing and heartbeat slow down, body temperature drops.
Animals that hibernate do not make any reserves for the winter, unlike squirrels or hamsters. The bear is a large animal, but it eats mainly berries, mushrooms, and fish. That is, everything that disappears with the onset of winter.
During the summer, bears feed intensively, accumulating subcutaneous fat. The thickness of the subcutaneous fat is on average 15 centimeters; this layer is enough so that the bear does not starve during hibernation and is not bothered by frost. Brown bears, unlike their counterparts, set up their homes for the winter. They use different branches and twigs for their dens.
But bears need sleep in winter not only as a means of fighting hunger. A pregnant female polar bear also hibernates. But she does not, does not arrange her den, but sleeps in a snowy hole.
This is how the bear hibernates in winter.
When winter ends and spring is already in full swing in the warmer air, bears wake up. The heart begins to beat more and more often, returning to its normal rhythm, breathing also quickens, and body temperature rises. The bears leave the den and return to their normal lives.
Nature uses many mechanisms to protect plants and animals from harmful effects external factors and dangers. Speed, strength, sharp teeth, poison is all of it active agents survival. Camouflage, symbiosis and suspended animation are passive methods that help to survive. The article will tell you about the winter hibernation of bears, answer questions about how clubfoot prepare for winter, when bears go into hibernation, 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: a decrease in body temperature by several degrees, breathing becomes rare, a slowdown in 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. The condition can last from a few days to many months.
What animals can hibernate?
Since childhood, everyone knows that in winter it goes into hibernation, during which it sucks its paw, and awakens only in the spring. And the answer to the question of when bears go into hibernation is known even to children - in late autumn.
In fact, bears do not go into real hibernation, which is essentially suspended animation of the body. They only fall into a shallow sleep, waking up easily if disturbed. During this sleep, the bears’ body temperature drops to 31 °C, despite the fact that normal temperature beast is approximately 38 °C. For comparison: the body temperature of the American ground squirrel, which is active state equal to 38 °C, during hibernation it drops to zero! Still, Toptygin’s body works in economy mode, the number of heart beats decreases to ten per minute, and metabolic processes slow down several times.
How a clubfoot bear prepares for hibernation. Fat accumulation
In order to successfully overwinter, two issues need to be resolved:
- accumulate energy reserves;
- prepare a room for wintering - a den.
Energy reserves are fat. To accumulate it, the bear spends the entire summer actively searching for food. He loves sweet wild berries, especially raspberries and strawberries, but he is not picky about food and eats roots, ants, fish, and small mammals. Closer to cold weather, the underskin layer of fat in bears 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 being 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, drink water or defecate for six months.
Preparing the den for wintering
The second thing is to prepare a shelter - warm enough so that you can hide in it from the frost, and safe so as not to become easy prey for the enemy.
The bear chooses the place for the future den very carefully. Depending on the species, this may be a depression between tree roots, a cave or rock niche, an abandoned anthill, or a hollow tree. Sometimes bears dig dugouts, strengthening the walls with branches; very rarely they build high dens - a structure made of branches on the ground, reminiscent of a large bird's nest.
The bottom of the shelter is covered with spruce branches, peat, moss, dry leaves, hay, and when the bears go into hibernation, 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, while completely filling the den, never covers the “window”, so well does the bear know how to choose a place for it.
In what month does a bear go into hibernation?
Scientists have long been closely studying this natural phenomenon, How 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 Europe this happens in different time. The following factors matter:
- gender, age and physiological state of the animal;
- yield of bear food;
- natural area;
- weather.
The first to leave for the winter in early November are pregnant females and mothers with cubs. Barn bears and males at the end of November, and at southern regions may last until mid-December.
In years with a particularly large harvest of nuts and acorns, these dates are shifted a few more weeks closer to winter.
If for some reason a bear did not have time to gain fat for the winter or arrange a home for itself, then it does not hibernate. Such animals are called connecting rods. They are very dangerous because they behave aggressively and viciously.
Now the reader knows at what time the bear goes into hibernation and how he prepares for it. It remains to be clarified that Toptygin emerges from the den 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.