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The polar bear (Ursus maritimus) is a bear native to the Arctic Ocean and its surrounding seas.The world's largest predator found on land,an adult male weighs around 400–680 kg (880–1,500 lb),while an adult female is about half that size.Although it is closely related to the brown bear,it has evolved to occupy a narrow ecological niche,with many body characteristics adapted for cold temperatures,for moving across snow,ice,and open water,and for hunting the seals which make up most of its diet.As it can hunt consistently only from sea ice,the polar bear spends much of the year on the frozen sea,although most polar bears are born on land.
The polar bear is classified as a vulnerable species.Of the 19 recognized polar bear subpopulations,5 are declining,5 are stable,2 are increasing,and 7 have insufficient data.For decades,unrestricted hunting raised international concern for the future of the species; populations have rebounded after controls and quotas began to take effect.For thousands of years,the polar bear has been a key figure in the material,spiritual,and cultural life of Arctic indigenous peoples,and the hunting of polar bears remains important in their cultures.
The IUCN now lists global warming as the most significant threat to the polar bear,primarily because the melting of its sea ice habitat reduces its ability to find sufficient food.Sea ice melting will also cause changes in their mating,and traveling patterns.The IUCN states,"If climatic trends continue polar bears may become extirpated from most of their range within 100 years." On May 14,2008,the United States Department of the Interior listed the polar bear as a threatened species under the Endangered Species Act.
