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Cooling and Thermal Conductivity in Three Small Alaskan Mammals

Peter R. Morrison, William J. Tietz
DOI: http://dx.doi.org/10.2307/1376478 78-86 First published online: 25 February 1957

Mammals are able to maintain their body temperatures in the face of cold stress through the insulation provided by their fur. In this study we explore a method for evaluating this insulating layer in dead animals and measure the modification of its effectiveness by changes in extent, thickness or air movement.

These studies were supported in part under contract between the University of Wisconsin and the Alaskan Air Command, Arctic Aeromedical Laboratory, Ladd Air Force Base, Alaska, and by a research grant from the Wisconsin Alumni Research Foundation.

Materials and Methods

Tundra redback voles (Clethrionomys rutilus dawsoni), tundra voles (Microtus economis macfarlani), and long-tail shrews (Sorex cinereus hollisteri) were trapped near Fairbanks, Alaska, in February and March of 1952. Bodies were obtained either from animals found frozen in live traps or from animals which died as a result of exposure or other laboratory tests. The temperature of the area from which the animals were taken varied from 0 to −43°C. and occasionally as low as −56°C., but the microclimate under the snow is much milder (Johnson, 1951).

The five Sorex, thirteen Clethrionomys and nine Microtus studied had average weights of 2.3, 14.3 and 20.4 gm., respectively. All animals were handled as little as possible and then only by feet or tail to prevent soiling by oils, moisture, or dirt which might cause clumping and breaking of the fur. It was difficult to keep the fur clean and even the fur of live animals in captivity seemed to have an affinity for foreign material.

Two methods were used to determine the rate of heat loss through the fur: (1) measuring the change in temperature of an animal body held at a constant ambient temperature; and (2) recording similar data from a fur-covered, metal cast of an animal's body. The temperatures of the …

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