Black bears (Ursus americanus) in the Sierra Nevada range of California do not reliably exhibit the classic pattern of compulsory winter dormancy generally reported for this species. Pregnant females and most other adults hibernate for approximately 3.5 months, but only 37% of males are winter dormant. Winter-active bears tend to use lower elevations where snow cover is sporadic, growth after autumn rains provides herbaceous foods, and acorns may remain on the ground. Warmer temperatures at these lower elevations also reduce energy costs for active bears. The absence of a single environmental or physiological factor that discriminates between winter-active and winter-dormant bears, however, suggests that a complex suite of factors affects a bear's decision to remain active or den.
- Volume 8
- Issue
- Pages 269-272
- Publication Date 1 January 1990
- DOI 10.2307/3872928
- File Size 219.69 KB
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