Metabolism of Varying Hare in Winter

It is of practical and theoretical interest to define the degree of cold at which warm-blooded animals must add to their basal rate of heat production. Scholander et al. (Biol. Bull., 99: 225–258, 1950) have described the procedure to be used in this definition and its basis. They have shown the temperatures causing the elevation of metabolism as a critical temperature in the metabolism of a number of arctic birds and mammals. The accumulation of information concerning metabolism and climate improves our comparative views of the adaptations by which animal heat production is suited to various climates. Accordingly we take the opportunity to record measurements indicative of the metabolism and critical temperature of an American varying hare, Lepus americanus macfarlani Merriam, captured near Anchorage, Alaska, in January, 1952. The experiments were conducted on five alternate days. Thirteen days after its capture the hare died from unknown causes. Its condition during the experiments and the metabolic measurements were so regular that they appear normal.