The duration of the period of hibernation of three species of vespertilionid bats. II. Laboratory studies

Abstract

Variation in the duration of the period of hibernation of three species of vespertilionid bats under laboratory conditions was great. Durations of the period of hibernation of the big brown bat (Eptesicus fuscus) ranged from less than a day to 908 h (37.8 days) at 5 °C and to 1227 h (51.1 days) at 2 °C. Those for the little brown bat (Myotis lucifugus) ranged from less than a day to 1398 h (58.2 days) at 5 °C and to 1827 h (76.1 days) at 2 °C. Those for Pipistrellus subjlavus (eastern pipistrelle) ranged from less than a day to 649 h (27.0 days) at 5 °C and to 864 h (36.0 days) at 2 °C. It is proposed that the tendency toward great variation is an inherent characteristic of the bats and is not a laboratory-induced artifact. Despite great variation, a temperature dependency of the frequency of arousal was demonstrated for E. fuscus, P. subjlavus, and M. lucifugus. Slopes of regression for E. fuscus, P. subflavus, and M. lucifugus derived from semilogarithmic plots of durations of the period of hibernation versus temperature are similar to each other and to those of hibernating ground squirrels. The regulating effect of temperature upon hibernation suggests that the frequency of arousal is controlled metabolically.