What is polar bear behavior

 





ANATOMY

The polar bear is one of the largest land predators on earth. The males of this bear species are up to 3 m long and reach a shoulder height of about 1.50 m. The weight of the males often reaches more than 650 kg, a single male weighed over 1000 kg! The females are significantly smaller and lighter.

Compared to other bears, polar bears have a relatively long, narrow head with a flat forehead. Your teeth are very strong. It has 42 teeth and has the typical shape of a predator's teeth. The eyes are brown and look forward. The polar bear has a protective membrane over its eyes, which probably protects against UV radiation. The polar bear can close its ears and nostrils while diving.

The polar bear fur is very dense, under the skin the polar bear has a thick layer of fat that protects it from the cold. Its white to cream-colored fur is an excellent camouflage in its polar environment when the bear is hunting its prey. The impression of white fur is created solely by light reflection: the fur is not colored white. It covers the entire body except for the muzzle and eyes and the soles of the feet. The polar bear changes its entire coat in May or June; this process can take several weeks. Its fur is oily and water-repellent; a polar bear emerging from the water can easily shake off all moisture before it freezes.

The outer fur hair of the polar bear is hollow on the inside. More recently it has therefore been assumed that the hair acted as a light guide that conducts the sun's energy from the outside to the inside, where it is absorbed by the bear's black skin, similar to glass fibers. However, recent studies have shown that hair is not a good light guide. However, the hollow hair ensures excellent thermal insulation, and the dark to black skin of the polar bear actually absorbs a lot of heat from the outside. In addition, the hair, together with the layer of fat, increase buoyancy when swimming.

The polar beard paws are fifteen. There is a strong, curved, non-retractable claw on each toe. The front paws are rounded, the back slightly elongated. The claws and long hair between paws and toes create friction on the ice. The front paws, which are up to 30 cm in diameter, are widened like a row and are partially webbed. Polar bears can skillfully move objects with their front paws. The balls of the feet are thermally insulated; Polar bears walk all over the sole of their feet, similar to humans.

Overall, polar bears are so well insulated against heat loss that they have to work actively against overheating, e.g. by swimming in cold water after long exertion, or by usually relatively slow, steady movement.

 

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LIVING SPACE AND MOVEMENT

Polar bears live in the Arctic ice regions, usually on the sea ice, near coastlines or islands. Except during the mating season and apart from mothers with their offspring, polar bears are loners. Only very rarely do two or more, mostly well-nourished males make "play friendships".

The bears go on long hikes and are quite good swimmers. In the north, individual polar bears have been spotted almost up to the pole. Polar bears do not mark or defend their territories! In the polar summer they are often found far inland on the continental mainland.

The average air temperatures in regions of perpetual ice are around 0 degrees C (summer) and -35 degrees C (winter), the water temperatures at -1.5 degrees C (summer) and -2 degrees C (winter). Thanks to the dense fur and the subcutaneous fat layer, such temperatures are not a major problem for a fully-grown polar bear.

A polar bear moves at an average of 5.5 km / h, but can briefly reach up to 40 km / h. Such an effort can quickly become tiring. Some polar bears have been seen swimming more than 100 km! You can also dive, about 4 m deep and for a period of a few minutes. Climbing steep ice cliffs is not a big problem. When descending snow slopes, polar bears assume an upward sloping position and use their front paws as brakes, or they simply slide down on their stomach. Polar bears move cautiously and backwards when they step into the water, or they jump into it upside down. When you get out of the water, especially when hunting seals, you develop amazing speed: you can jump up to 2 m high!

 

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NUTRITION

Polar bears are almost exclusively carnivores. They feed mostly on seals, mostly ringed seals. The polar bear often lies in wait for a seal at one of its breathing holes in the ice; he pushes her onto the ice with one swipe of his paw when she appears and kills her with bites in the head and neck. Polar bears can also surprisingly attack seals lying near a breathing hole by diving under the ice and through the breathing hole themselves, or sneaking up on a seal on the ice and suddenly attacking it from a short distance. With its extremely touch-sensitive paws, the polar bear recognizes whether and when a seal is approaching the breathing hole under the ice. But the seal can feel even the slightest vibrations, so that the polar bear has to be very calm.

It is also often observed that polar bears feed on fish, young walruses or stranded whale carcasses. Little polar bears learn the hunting technique - like other living things - from their mother.

The polar bear usually loses most of its weight in summer: when the ice melt drives it to the mainland, only a number of small mammals and birds are on its menu, far too few for an animal of this size. That's why they often eat grass, moss and berries.

 

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SENSE ORGANS

Polar bears can smell seals and whale carcasses over a distance of more than 50 km and use their noses to find animals buried in the snow.

The eyes remain open during dives. Visual acuity under water is apparently very good: Polar bears can target fish (especially flatfish) and graze on algae while diving.

 

 

 

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REPRODUCTION, GROWTH AND AGE

Polar bears are sexually mature at the earliest at 4 (W) or 6 years (M). They prefer to mate in April. However, germ development rests until about October. This ensures that the mother and offspring survive the winter: if the female could not take in enough food over the summer, the embryo will not develop any further.

Unlike other bears, polar bears do not hibernate. At the end of autumn, pregnant female polar bears alone dig a snow cave in which they winter and give birth to their young around January. Snow does not conduct heat and therefore insulates well. The cave is mostly located on the south-facing slope of a snow hill and measures a maximum of 2.5 meters. Polar bears usually give birth to 2 cubs. At birth, the cubs are the size of a rat and blind and weigh around 600 grams. Polar bear milk has a very high fat content of around 33%. Polar bear babies are suckled for about one and three quarters of a year after they are born. A female polar bear only has offspring every 3 years. During the entire period of rearing the young, the mother is always ready to defend the young with all her strength - if necessary at the risk of her own life. Before the mother becomes pregnant again, the young are chased away by herself or by the next male willing to mate. Siblings often stay together for a while.

The eyes of the little bears open within the first month of life. After about 2 months the cubs can run around in the cave. They then already have a thick, white fur and milk teeth. The young leave the cave for the first time in late March to mid-April; they are then already 10 to 15 kg. They stay in the cave for up to 12 days, where they usually stay during the day and at night to sleep. During this time, the mother forcefully forces them to expose themselves to the cold, which is not so easy for little polar bears to endure. Her locomotor muscles also develop in this transition phase before the mother finally leads her to the sea ice. During the hike to the pack ice, there are frequent breaks during which the young are suckled. The young are carried by their mother through deep snow and water. The young are already eating the first prey that the mother hunts after their winter rest; they are then 3 to 4 months old. Breast milk and seal fat ensure rapid growth: after 8 months, a polar bear weighs almost 50 kg. The little polar bears soon start trying to hunt, but in the first few months they are quite clumsy and mostly unsuccessful.

Polar bears live for up to 20 to 30 years; however, only a few live to be older than 15 to 18 years. The oldest known Arctic polar bear lived 32 years, the oldest polar bear in captivity 41 years. The age of a polar bear can be determined from the annual rings in its teeth.

 

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POLAR BEARS AND HUMANS

Polar bears are now a protected species after having been hunted for decades. Only the Inuit are allowed to hunt polar bears. The only natural enemy of the polar bear (other than the polar bear itself) is humans. For the Arctic Inuit, the polar bear is an important source of meat, fat and fur, along with seals and walruses.

With the increasing spread of human settlements in arctic regions, for example through the oil production in Alaska and Siberia, there are more unplanned encounters between polar bears and humans. Such encounters are often fatal for humans. The bears are also not afraid to look for human settlements in search of food and feed on waste or food supplies: polar bears, like all bears, are extremely curious. It is on such occasions that people are still surprised by polar bears today. For these and other reasons there is great interest in research, e.g. in the migration routes and habitats of polar bears.

 

 

 


LITERATURE AND OTHER LINKS


task:

Find out about the life of polar bears and gather information on the following aspects:

How is the polar bear able to survive in the cold?


 

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