Frequency of Spontaneous Arousal from Hibernation in Bats

Abstract

ALL species of mammalian hibernators ‘spontaneously’ raise their body temperatures to or near the normal homeothermic level at intervals during a winter's hibernation. The frequency with which such arousals occur is in part at least a species-specific characteristic ranging from an arousal every 2–7 days in hamsters¹ to maximal periods of 12–20 days in various species of the genus Citellus, and 20–33 days in Glis glis². Folk³ has reported that 4 bats (^{Eptesicus fuscus}) remained without movement for 64–66 days in the dark at ambient temperatures of 4°–8° C. However, reliable information about the maximal duration of continuous hibernation (or conversely the frequency of spontaneous arousal) is available for only a few species. Reports of long periods of continuous hibernation based on daily visual observations of the postures of hibernating animals must be interpreted with great caution as there is no well-documented correlation between postural adjustment and change in body temperature in many species of hibernators.