Hibernation and seasonal fasting in bears: the energetic costs and consequences for polar bears
TL;DR
Bears lose 15-30% of pre-hibernation body mass during hibernation
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This paper quantified the energetic costs of bear hibernation and the fitness consequences of different reserve levels. The finding that bears lose 15-30% of pre-hibernation body mass provides the empirical basis for reserve calculations. The emergence energy surge calculation (15-20% additional) comes from analyzing this data.
Key Findings from Robbins et al. (2012)
- Bears lose 15-30% of pre-hibernation body mass during hibernation
- Hyperphagia involves consuming up to 20,000 calories daily (10x normal)
- Minimum entry weight thresholds determine survival probability
- Emergence requires significant additional energy beyond dormancy burn
- Bears gain 3-4 pounds per day during hyperphagia
- Total weight gain of 150-200 pounds over 8-10 weeks
- 15-25% of consumed calories lost as heat during fat synthesis
- Hibernation requires approximately 525,000 calories of stored fat
Used in 2 chapters
See how this research informs the book's frameworks:
Quantified energetic costs of bear hibernation - 15-30% mass loss plus 15-20% emergence surge provides empirical basis for reserve calculations.
See energetic requirements →Quantifies fat accumulation rates during hyperphagia and consumption rates during dormancy - 150-200 pound weight gain over 8-10 weeks.
See storage economics →Cited in 9 pages
Mechanism Hyperphagia Mechanism Hibernation & Reserve Strategy Mechanism Fat Storage Organism Grizzly Bear Citation Tracking the seasons: the internal calendars of vertebrates Citation Hibernation in black bears: independence of metabolic suppression from body temperature Citation Body mass, metabolic rate, heart rate, and respiratory quotient during hibernation in black bears Book Chapter Hibernation Reserve Strategy Book Chapter Storage vs Immediate Use