Polar bears are protected under the Marine Mammal Protection Act, which prohibits the take (i.e., harass, hunt, capture, or kill) of all marine mammals. Please click the link provided after "For more information" to access the Services Marine Mammals Management Polar Bear website. Throughout the Arctic, polar bears are known by a variety of common names, including nanook, nanuq, ice bear, sea bear, isbjorn, white bears, and beliy medved. Genetic research has confirmed that polar bears evolved from grizzly (brown) bears (Ursus arctos) 250 to 300 thousand years ago (Cronin et al. 1991, p. 2990; Talbot and Shields 1996a, p. 574). Only in portions of northern Canada and northern Alaska do the ranges of polar bears and grizzly bears overlap. Polar bears are the largest of the living bear species. Polar bears are carnivorous and an upper level predator of the Arctic marine ecosystem. Polar bears prey heavily throughout their range on ringed seals (Phoca hispida) and, to a lesser extent, bearded seals (Erignathus barbatus) and in some locales, other seal species. Polar bears are characterized by a late age at sexual maturity, small litter sizes, and extended parental investment in raising young, factors that combine to contribute to a very low reproductive rate. Reproduction in the female polar bear is similar to that in other ursids (bears). Females generally mature and breed for the first time at 4 or 5 years and give birth at 5 or 6 years of age. Litters of two cubs are most common, but litters of three cubs are seen sporadically across the Arctic.
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