Thermal energetics and thermoregulatory costs of small arctic mammals

Chappell, Mark

Thermal energetics for shrews, weasels, and lemmings from arctic environments were evaluated by using physical and physiological energy exchange data in an energy budget equation. This approach allowed quantification of the effects of different temperature and radiative and convective regimes on metabolic heat production requirements. Tests of the predictive accuracy of the technique were carried out by placing fur-covered, internally heated metal casts of the animals in natural settings and comparing predicted with actual power input requirements. Test results were good, confirming the accuracy of the energy budget model. Thermoregulatory energy requirements were computed for small mammals in several microclimate regimes typical of the Alaskan North Slope region. Estimations were also made of daily and yearly metabolic expenditures by integrating energy budget information with climatic data and the behavior patterns of the animals. The energy requirements of these animals are high throughout the year, but differ significantly between the various available microhabitats. Maintenance of a positive energy balance depends heavily on efficient foraging strategies, selection of the most energetically favorable microhabitats, and the use of winter nests.

Thermal energetics and thermoregulatory costs of small arctic mammals

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