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Brown browns and grizzly bears are classified as the same species even though there are notable differences between them. Kodiak bears are classified as a distinct subspecies from those on the mainland because they have been isolated from other bears since the last ice age about 12,000 years ago. “Brown bears” typically live along the southern coast of the state where they have access to seasonally abundant spawning salmon, a rich array of vegetation and milder climate. This allows them to grow larger and live in higher densities than the “grizzly” cousins in the northern and interior parts of the state.
Brown Bear or Black Bear?
Brown bears are larger than black bears, have a more prominent shoulder hump, less prominent ears, and longer, straighter claws. They also have a concave appearance to their forehead in profile, versus a straight or roman nose profile of a black bear. Color is not a reliable key in differentiating these bears because black and brown bears have many color phases.
Brown bear individuals may be active at any time of the day, but generally forage in the morning and evening and rest in dense cover by day. They may excavate shallow depressions to lay in. Home ranges can be as large as 1,000 square miles, but are on average between 30 and 160 square miles, with male ranges nearly seven times greater than female ranges. Although generally solitary, they occur in large groups in concentrated feeding areas such as salmon spawning streams, sedge flats, open garbage dumps or on whale carcasses. Because of this, they have developed a complex language and social structure to express their feelings and minimize fights. In winter when food is unavailable or scarce, bears enter a state of torpor where body temperatures, heart rate and other metabolic rates are drastically reduced (although not reduced to the level of a true hibernator, like marmots). While in the den, they do not eat, drink, urinate or defecate. Pregnant females are usually the first to enter dens in the fall and, with their newborn cubs, are the last to exit dens in the spring. Brown bears have an exceptionally acute sense of smell, exceeding that of dogs. Their eyesight and hearing are comparable to humans. They can run in short bursts up to 40 miles per hour and are excellent swimmers.
Brown bears are omnivores. They are very adaptable and consume a wide variety of foods. Common food includes salmon, berries, grasses, sedges, ground squirrels, cow parsnip, carrion and roots. In many parts of Alaska, they are capable predators of moose and caribou, especially calves.
Brown bears are considered monogamous, having one mate at a time. Mating season is May to July and cubs are born in the den during January and February. Twins are most common. When cubs emerge in June, they may weigh up to fifteen pounds. Families stay together for two or three years, and after separation, female cubs tend to stay near where they are raised while males disperse farther. Most brown bears are sexually mature at five years of age.
Population Status, Threats & Conservation
Alaska has over 98% of the Unites States population of brown bears and more than 70% of the North American population. Brown bear populations in Alaska are healthy and productive. Densities vary depending on the quality of the environment and, in areas abundant with salmon, densities are as high as one bear per square mile. The Alaska Department of Fish and Game is responsible for maintaining healthy populations of brown bears throughout Alaska, conserving bear habitat, preventing overharvest and conducting studies necessary to understand population requirements and how bears and people can co-exist.
The Alaska Zoo is part of the Anchorage Bear Committee, a partner group formed under the management of Alaska Department of Fish and Game to raise awareness of how to coexist and recreate safely in bear country. Click here to learn how you can be Bear Aware!
Notebook series, ADFG
Dewey, T. and L. Ballenger. 2002. "Ursus arctos" (On-line), Animal Diversity Web