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Behavior, Biochemistry, and Hibernation in Black, Grizzly, and Polar Bears

Ralph A. Nelson, G. Edgar Folk, Jr., Egbert W. Pfeiffer, John J. Craighead, Charles J. Jonkel and Dianne L. Steiger
Bears: Their Biology and Management
Vol. 5, A Selection of Papers from the Fifth International Conference on Bear Research and Management, Madison, Wisconsin, USA, February 1980 (1983), pp. 284-290
DOI: 10.2307/3872551
Stable URL: http://www.jstor.org/stable/3872551
Page Count: 7
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Behavior, Biochemistry, and Hibernation in Black, Grizzly, and Polar Bears
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Abstract

Annual behavioral and biochemical patterns of black bears (Ursus americanus), grizzly bears (Ursus arctos horribilis), and polar bears (Ursus maritimus) were reviewed. We propose that black and grizzly bears show 4 annual physiological stages: Stage I -- hibernation, in which lean body mass is preserved and body fat supplies energy; Stage II -- walking hibernation, in which the biochemistry of hibernation is integrated with physical activity, but food and water intake are minimal; Stage III -- normal activity, in which patterns are consistent with those of nonhibernating mammals; and Stage IV -- hyperphagia, which increases fat reserves for hibernation. For polar bears, using published reports and recently collected data, we propose that all 4 stages are possible and that polar bears appear able to shift between Stages I and II in both summer and winter, which permits successful adaptation to the arctic environment.

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