Three bear species can be found in Alaska: polar bears, brown bears, and black bears. Both brown and black bears are found in the temperate rainforests of Southeast Alaska. Brown bears are distinguished from black bears by their large size, distinctive shoulder hump and long, straight claws (both adaptations for digging roots and small mammals), and dish-shaped face. Color is not a useful identifying trait while traveling Alaska, as both brown and black bears come in a variety of colors.
Brown and grizzly bears are of the same species, Ursus arctos, causing confusion. The term "grizzly" should be reserved for the smaller brown bears of the interior and Arctic. The brown bears of Southeast Alaska seen on our Alaska cruise are best called coastal brown bears. Males reach over 1,000 pounds and stand nine feet on their hind legs. We believe that the coastal bears are larger because of the abundance of protein-rich salmon in their diet. The greatest density of coastal brown bears occurs on Admiralty Island, where there may be one bear per square mile. This is exceptional.
Both male and female brown bears spend the winter sleeping in a den in the mountains of coastal Alaska where the snowpack is dependable. It is not a deep hibernation, and a sleeping bear can be aroused. Females give birth to one to four (most commonly two) small, hairless cubs in the winter den, and then convert their body fat into milk for the cubs until they leave the den in spring. (She could do neither of these while in deep hibernation.) Cubs stay with their mothers for at least two years, and longer where food is scarce. After the female has separated from her cubs, she may mate again (May - July) to produce the next litter. The only stable social unit is the female and her cubs; otherwise, brown bears are solitary, and males may pose a risk to cubs.
Brown bears consume a wide variety of food. During spring we see them foraging in coastal meadows eating sedges and digging for roots. They may prey upon newborn deer, but probably most deer are taken as carrion. As berries ripen these become important in the diet. However, brown bears are best known for their relationship to spawning salmon. Bears aggregate at spawning streams. The biggest males claim the preferred fishing spots, but when the salmon run is at its peak there is usually enough for all. The adult bears often take only the fat-rich tissues - brains and gonads - to deposit the fat that they will need to fuel their winter sleep. The fish and fish parts that are not eaten by the bears may be eaten by bald eagles, river otters, mink, and other predators. Eventually the fish decompose and their nutrients enter the streamside vegetation.
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