Winter Activity of Red Squirrels in Interior Alaska

The mammals that inhabit the subarctic spruce forest or taiga may be classified into two groups on the basis of their winter activity—those that live above the snow and are therefore subjected to the vicissitudes of weather, and those that live or retreat beneath the snow in a warmer and more stable environment (see Pruitt; Arctic, 10: 131–138, 1957). Those that weigh upwards of 200–250 grams usually live above the snow—hare, lynx, fox, wolf, moose, caribou. Those that weigh less than about 200 grams usually live or retreat beneath the snow—weasels, voles, shrews (Formosov, Materials for Fauna and Flora USSR, Moscow (N.S.), Zoology 5: 152 pp., 1946). The red squirrel (Tamiasciurus hudsonicus) is just on the borderline between these two groups. Moreover, the red squirrel is one of the most obvious mammals in the taiga. It is one of the mammals adapted to the taiga and may be considered characteristic of it. There are, however, conflicting reports in the literature regarding its winter activity. Dice (Jour. Mamm., 2: 20–28, 1921) stated that it was seldom noted when the air temperature fell below −30°F. in interior Alaska, while Murie (Jour. Mamm., 8: 37−40, 1927) implied that it was active all winter long.