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.
- Volume 5
- Issue
- Pages 284-290
- Publication Date 1 January 1983
- DOI 10.2307/3872551
- File Size 279.28 KB
- Download