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Polar Bear Facts
About Polar Bears
Some general polar bear facts: The habitat of polar bears is largly within the artctic circle, which includes the Arctic Ocean, it's surrounding seas and surrounding land masses. It is the largest land carnivore in the world, and also the largest bear together with the omnivores Kodiak Bear. An adult male weighs about 350-680 kg, while a female weighs about half that size. The polar bear is closely related to the brown bear, but has evolved to cover a small ecological niche. Its body has evolved to cope with freezing temperatures, to move across snow, ice and open water, and for hunting seals which makes up their main diet. Although polar bears are born on land, they spend most of their time at sea.
Polar bears are classified as a vulnerable species, so not quite endangered yet, but 8 of the 19 sub populations is in decline. For decades there was concern about the survival of the species because they were hunted without restriction, but populations have rebounded after quotas and controls began to take effect.
Global warming is now listed as the most significant threat to polar bears, mostly because the melting of the ice caps prevent them from finding sufficient food. According to the IUCN, polar bears will be extinct within 100 years if climate trends continue.
Polar Bear PicturesClick thumbnail to view full-size
Polar Bears and Global Warming
The IUCN, Arctic Climate Impact Assessment, United States Geological Survey and many leading bear biologists have expressed great concern about the effects of global warming and the fact that that it threatens the survival of the polar bear.
The main problem with global warming is the loss of habitat that it causes and therefore malnutrition and starvation of the polar bear. They hunt seals from a platform of ice, and global warming causes this ice to melt earlier, driving the bears to shore before they have built up sufficient fat reserves to survive the late summer and fall when food is scarce. Depletion of see ice also causes the polar bear to have to swim longer distances which causes further depletion of energy and causes drowning occasionally. Thin sea ice also deforms more easily, which seems to make it harder for polar bears to access seals. Improper nutrition leads to lower birth rates in adult females and lower survival rates of polar bear cubs and juvenile bears, as well as poorer body condition in bears of all ages.
In addition to these problems, global warming also makes it harder for pregnant females to build suitable dens due to the changes in sea ice. They also have to swim longer distances between the pack ice and land which is favoured for building dens, as the distance between pack ice and coast increases. Disease causing parasites and bacteria would flourish more in a warmer climate.
Increased interaction with humans, including fatal attacks are also more likely to occur, as the ice melts and bears start looking for food on land. Therefore it is important for us to be aware of these polar bear facts.
Other factors such as pollution and oil and gas development has also had a negative effect on the survival of polar bears. Due to their position at the top of the food chain, with a diet of blubber that contains halocarbons concentrate, their bodies are among the most contaminated of Arctic mammals. Oil spills on the other hand can cause oil to get onto the fur of polar bears, which in turn can affect its insulation and cause the bear to die from hypothermia. They also try to lick the oil from their fur which causes kidney failure.
Polar Bear Habitat
Polar bears are often referred to as a marine mammal because it spends so many months a year at sea. The preferred polar bear habitat is the sea ice covering the waters over the continental shelf and the Arctic inner-island cluster of islands. Know as the 'Arctic ring of life', these areas have high biological productivity compared to the deep waters of the high Arctic. Polar Bears tend to be found where water meets ice, to hunt the seals that makes up most of its diet. The polar bear is therefore found along the perimeter of the polar ice pack, rather than further up north where the density of seals are much lower.
Annual ice contains water that appear and disappear as the weather changes, which means that polar bears must follow their prey as they migrate according to these changes. In some areas the ice melts completely, forcing the polar bear to go on land until the next freeze-up. In other areas, polar bears retreats north where the ice remains frozen year round.
Polar Bear CubsClick thumbnail to view full-size
Polar Bear Behaviour
Polar bears are not territorial like grizzly bears. Although stereotyped as aggressive, they are cautious and would often choose the escape route rather than risk a confrontation. Adult polar bears are solitary, but have often been seen playing for hours and even sleeping in a warm embrace. In 1992 a photographer near Churchill took pictures of a polar bear, known as the Churchill polar bear now, playing with a Canadian Eskimo Dog a tenth of its size. It continued for ten days, for no apparent reason. This is uncommon though as polar bears are usually aggressive towards dogs.
Biology and Diet
A polar bear is the biggest land carnivore, more than twice the size of a Serbian Tiger. The largest polar bear ever found reportedly weighed 1,002 kg. Compared to it's closest relative, the brown bear, polar bears have a longer body build and longer neck and skull. The feet are very large to help with walking on the ice and swimming.
Polar bears are very well insulated by up to 10 cm of blubber, their hide and their fur. They overheat at temperatures above 10 °C. The polar bear has an extremely well-developed sense of smell, being able to detect seals a mile away and under 3 feet of snow. They are excellent swimmers, and have been seen as far as 200 miles from land.
The polar bear is the most carnivores of the bear family, and its diet consist mainly of ringed and bearded seals.The polar bear's most used hunting method is called still-hunting, where it waits at the a breathing hole until a seal surfaces and after smelling its breath when it exhales, it reaches in a paw and pulls it out. It then kills the seal by crushing its skull with its jaws. It also stalks seals that are resting on the snow, and uses the immense strength of its front legs to break through the ice where female seals have created birth lairs.
Mature bears only eat the calorie rich blubber, while younger bears eat the protein rich red meat. A polar bear is an immensely powerful predator, and sometimes hunt walruses which is twice it's size. They have also been known to hunt beluga whales at breathing holes, which is about the same size as a walrus. Polar bears can fast for several months when food is not available, and have also been known to eat other wild foods such as muskox, reindeer, birds, eggs, rodents, shellfish, crabs, and other polar bears. They may also eat plants, but it doesn't make up any significant part of their diet.
I hope you enjoyed these polar bear facts and that you have learned something new about polar bears :)