A Comparison of Some Seasonal and Temperature-Induced Changes in Peromyscus: Cold Resistance, Metabolism, and Pelage Insulation

The cold resistance of deer mice captured during the winter was greater than that of summer mice and was accompanied by a greater pelage insulation and a lower oxygen consumption at 1–2 °C. On the other hand, the enhanced cold resistance of deer mice previously acclimated to cold was not accompanied by differences in pelage insulation. Moreover, in white-footed mice previously acclimated to different temperatures, oxygen consumption was similar at 1–2 °C. These data indicate that the seasonal changes observed in Peromyscus are not identical to changes produced by acclimation in the laboratory. Environmental factors responsible for these differences are discussed.