BODY INSULATION OF SOME ARCTIC AND TROPICAL MAMMALS AND BIRDS

Insulation measurements on raw skins from 16 arctic and 16 tropical mammals are given. There is, as would be expected, a good correlation between the thickness of the fur and the insulation. The smaller arctic mammals (weasels, lemmings) have much less insulation than the larger and overlap many of the tropical forms. From the size of a fox to the size of a moose there is no correlation between insulation and body size, they all have about the same insulation per surface area. When submerged in ice water, seal blubber retains about the same good insulation, as compared with measurements taken in 0° C. air. In the polar bear, heat transfer through the fur increases 25-50 times when submerged, because of complete wetting of the skin surface and absence of blubber. The beaver is slightly better off when submerged, as it retains an insulating layer of air in the fur next to the skin.