Dying out, but not giving up. How polar bears evolve to survive

Dying out, but not giving up. How polar bears evolve to survive

International Polar Bear Day is celebrated annually on February 27. The main purpose of this day is to spread information about polar bears and draw public attention to the protection of the largest land-based predator on the planet. After all, this one can become the first victim of global warming.

 

Polar bears have shrunk in size

 

According to rough estimates of scientists, today there are about 20-25 thousand polar bears in the world. An interesting fact is that the brown bear was the ancestor of the polar bear. The polar bear has perfectly adapted to life in the Far North, among the sea ice. They live on arctic sea ice. Here they hunt, live, breed and even equip dens. Polar bears live in Canada, the USA (in Alaska), Russia, Norway (on the island of Spitsbergen) and Denmark (in Greenland). Canada is home to the majority of polar bears, about a third of the total. And polar bears do NOT live in Antarctica near the South Pole. Penguins live there.

Polar bears are now in danger from climate change and global warming. The Arctic ice is melting, and the habitat of these animals is getting smaller. They depend on sea ice, which now forms later, melts earlier, and this limits feeding time. In summer, bears increasingly come out to people and spend more time on land, where there is much less food than in the ice. Due to the lack of food, the bears have become smaller. Studies have been conducted since the 80s of the last century and now scientists argue that although polar bears can still boast of impressive size, their weight has decreased by an average of 30-40 kilograms. This was especially true for females, who need to accumulate fat reserves in order to bear and feed their young. Bears have begun to give birth less often and fewer babies.

Ian Sterling of the University of Alberta said that when he studied a group of bears in the Hudson Bay area last November, he counted 107 individuals, but only two females with calves. Usually, during the breeding season, the number of females with babies reached 20-25 pieces.

In addition, these animals suffer from the pollution of the world’s oceans. Exploration for oil and gas sites is also threatening polar bears. There is a potential risk of habitat destruction, and contact of these animals with oil spills reduces the insulating effect of bears’ fur: they need to expend more energy to keep warm. In addition, swallowing oil while hunting – animals can be poisoned. Despite their more than impressive size, bears are very vulnerable: close contact with people and their garbage (yes, bears often rummage in landfills) can poison them, cause irreparable harm to the body, and affect the ability to reproduce.

The largest predator

The polar bear is still the largest land-based predator. Individual specimens can weigh 800 kilograms, females weigh half as much. If an adult male stands on his hind legs, then his growth can reach three meters.

The polar bear is at the highest point of the Arctic evolved way of life. They are only threatened by humans and other polar bears. Earlier it was believed that killer whales hunt bears, but scientists do not confirm this.

Iceberg rider

 

The polar bear has many names: the Vikings called the polar bear “the deer of the white sea”, “the storm of seals”, “rider of icebergs” and “sailor of ice floes”. They believed that a polar bear has the strength of 12 men and a mind of 11. The Sami called the polar bear “an old man in a fur coat” and never a “bear”, fearing to offend and inadvertently summon him. The Inuit called him Nanuk (a respected animal) and Pihokahak (the ever-wandering). In Norway and Denmark – “ice bear”, in Eastern Greenland – Tornassuk (Master helping spirits).

Polar bears are actually black. Polar bear fur is essentially colorless and looks white only because it reflects visible light. Beneath all this thick fur, their skin is almost black.

White Walkers

 

Polar bears are some of the best travelers in the world. A bear can walk three thousand kilometers in a month. Their paws the size of a plate can reach 30 centimeters in diameter. Tufts of fur between the toes keep warmth, and on the soles there are special black pads, called papillae, that keep the bear even on the slippery ice. The polar bear is the perfect swimmer. The front legs act like big oars, and the rear legs he steers. Polar bears can be on the high seas for several days. Bears swim from one piece of ice to another in search of prey. Their wide front legs are excellent for swimming, and they use the hind legs as a rudder. The record recorded bearish swim was 685 km. The bear swam this distance over the Beaufort Sea, sailing from Alaska to the drifting perennial ice. The swim lasted nine days, during which time her one-year-old cub died, and the bear herself lost 20% of her body weight. Scientists tracked her using a GPS beacon.

Polar bears are classified as marine mammals. They spend most of their lives on the sea ice of the Arctic Ocean and in the ocean itself, so polar bears are the only species of bears that can be considered marine mammals.

 

On the hunt

 

Despite their impressive size and amazing endurance, polar bears cannot be called successful hunters. They can smell a seal a kilometer away, wait for hours at the hole until it appears on the surface, but often the hunt is not crowned with success. Sometimes bears overturn an ice floe with seals. But they can handle walruses only on land. Bears do not disdain carrion, eat birds, ruin their nests and eat up frail vegetation that has managed to grow in the Far North. But if the hunt was still successful, then polar bears hide part of the prey. True, this is not typical for everyone. Scientists have found that only 19 out of a thousand bears are thrifty. Going out to people, polar bears ravage the warehouses of Arctic expeditions and feed on garbage dumps.

Polar bears are the most carnivorous of all bear species. The main source of calories for them is the fat of marine animals. They don’t digest protein as well as their brown cousins. It is seal fat that supports them for most of the year and during long fasts. So with a successful seal hunt, the bears first of all eat the skin and fat, and leave the carcass to the Arctic foxes. They can also share their meal. Scientists have witnessed how 14 polar bears were feeding at once near one walrus carcass. Moreover, the weaker ask permission from the strong, circling around and touching their noses with their nose.

 

Have you ever had a grizzly bear?

 

In 2006, scientists confirmed that polar bears and grizzly bears can interbreed with each other. Such hybrids are called “grolar bears” or “pizzly bears”. Outwardly, such cubs resemble an intermediate link between their parents, possessing the external characteristics of both, but most often they are born from female polar bears, so that they grow and behave like ordinary polar bears. Their ability to interbreed is not surprising if we remember that polar bears evolved from brown bears more than 150 thousand years ago.

Childhood

 

The female raises cubs in dens under the snow. She digs them in the fall, and the bears have favorite places – on Wrangel Island or on Franz Josef Land. Cubs are born in the middle or late arctic winter. The entire gestation period is 250 days. Babies are born tiny and helpless, but by April, when the female comes out of hibernation, they are already gaining weight and together with their mother go on the first hunt in their life. During her life, the bear brings 10-15 cubs. Kids stay with her for up to one and a half years. All this time, the female feeds them with milk – the fattest in the world (31% fat at the time of birth of cubs). This provides enough calories for the cubs to grow rapidly.

 

Survival odds

 

The number of polar bears is projected to decline by 30% by 2050. This is the first species to be threatened by global warming. But humans can help polar bears and other animals survive by reducing harmful emissions and switching to alternative energy sources.

 

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