Responses of Captive Common Vampires to Cold and Warm Environments

Abstract

When exposed to a cold environment (3°–5°C) common vampires quickly respond by increasing their food consumption and muscular activity. Both functions return promptly to normal levels when the ambient temperature is again raised. During relatively brief periods of cold exposure the animals remain normally alert and responsive, showing no evidence of induced torpor. They die, however, from within a few hours to three days when they are continuously exposed to temperatures of 3°–5°C. The great individual variation in the tolerance of cold observed among the experimental animals may indicate a capacity for physiological acclimation in captive specimens; nevertheless, the vampire's inability to withstand prolonged periods of cold exposure undoubtedly places a physiological limitation on its capacity to extend its range into more temperate latitudes. Collectively the observations suggest that the vampire bat is homeothermic. It raises its heat production by increasing metabolism and muscular activity when exposed to cold. Incidental observations upon vampires in warm environments indicate that the upper critical environmental temperature lies in the range of 27°–30°C.