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Hibernation in Black Bears: Independence of Metabolic Suppression from Body Temperature

TitleHibernation in Black Bears: Independence of Metabolic Suppression from Body Temperature
Publication TypeJournal Article
Year of Publication2011
AuthorsToien, O, Blake, J, Edgar, DM, Grahn, DA, H. Heller, C, Barnes, BM
JournalScience
Volume331
Pagination906–909
Abstract

Black bears hibernate for 5 to 7 months a year and, during this time, do not eat, drink, urinate, or defecate. We measured metabolic rate and body temperature in hibernating black bears and found that they suppress metabolism to 25% of basal rates while regulating body temperature from 30° to 36°C, in multiday cycles. Heart rates were reduced from 55 to as few as 9 beats per minute, with profound sinus arrhythmia. After returning to normal body temperature and emerging from dens, bears maintained a reduced metabolic rate for up to 3 weeks. The pronounced reduction and delayed recovery of metabolic rate in hibernating bears suggest that the majority of metabolic suppression during hibernation is independent of lowered body temperature.

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