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- Title
SEASONAL METABOLIC ACCLIMATIZATION IN A NORTHERN POPULATION OF FREE-RANGING SNOWSHOE HARES, LEPUS AMERICANUS.
- Authors
SHERIFF, MICHAEL J.; KUCHEL, LOUISE; BOUTIN, STAN; HUMPHRIES, MURRAY M.
- Abstract
Seasonal acclimatization in high-latitude endotherms may involve increases or reductions in body size and metabolic rate to, respectively, augment thermoregulatory capacity or reduce energy requirements. We investigated seasonal acclimatization in a northern population of wild snowshoe hares (Lepus americanus) that is exposed to low food availability and extremely cold temperatures in winter. Snowshoe hares were livetrapped and transported to a nearby mobile laboratory. Hares were placed in a metabolic chamber and oxygen consumption was measured for 55 min at each of the following temperatures: 10°C, 0°C, -10°C, -15°C, and -20°C. Hair length and density were measured on a sample of collected hares. Snowshoe hares maintained similar body mass and body temperature between the seasons, but average resting metabolic rate and thermal conductance were, respectively, 20% and 32% lower in winter than in autumn. The lower critical temperature was -10°C to -15°C in winter and 0°C to -10°C in autumn. Guard hairs were 36% longer and 148% denser in winter than autumn, whereas downy hairs were the same length but 128% denser in winter than autumn. Collectively, these results suggest that resource constraints associated with a herbivorous diet in regions and seasons of poor forage quality favors an energetically conservative approach to winter acclimatization.
- Subjects
SNOWSHOE rabbit; LAGOMORPHA; INDIRECT calorimetry; THERMAL conductivity; ACCLIMATIZATION; BODY temperature
- Publication
Journal of Mammalogy, 2009, Vol 90, Issue 3, p761
- ISSN
0022-2372
- Publication type
Article
- DOI
10.1644/08-MAMM-A-247R.1