Thermoregulation in winter-acclimatized common eiders (Somateria mollissima) in air and water

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Abstract
Metabolic heat production, body temperature, and skin temperatures of the back and breast were measured and the thermal conductance, and thus insulation, estimated in winter-acclimatized common eiders (Somateria mollissima) exposed to air and water. When exposed to low air temperatures, the plumage was responsible for most of the insulation. When exposed to water, the insulation in the plumage was reduced. This decrease was, however, compensated through increased peripheral vasoconstriction. A low total thermal conductance lowers the energetic costs of existence in cold environments. This reduces the nutritional demands, and may be an adaptation to living in polar and subpolar regions where temperatures are low and where the short day length during winter may reduce the time available for feeding.