Impact of Climatic Variation on the Hibernation Physiology of Muscardinus avellanarius

Abstract

Climate change will not only directly affect climatic parameters, such as temperature and precipitation, but ultimately also ecological and physiological parameters of animal species. Our study investigates the effects of variation in climatic conditions, as experienced by climate change, on hibernation physiology and energy balance of a small hibernating mammal, the hazel dormouse (Muscardinus avellanarius). To understand whether ambient conditions indeed impact thermoregulatory patterns (frequency of arousals) and energy budgets during hibernation, we measured skin temperature and metabolic rate of M. avellanarius under natural conditions during two winters of different strengths. Our results show that environmental conditions did significantly alter hibernation parameters in M. avellanarius at different levels. M. avellanarius did not compensate for changes in ambient temperature, but body temperature followed ambient temperature for most of the hibernation season (with skin temperature down to −2.9°C). Arousals occurred more frequently during warmer months, also after seasonal effects were eliminated, causing substantial additional energy expenditure. We conclude that hibernating small mammals such as M. avellanarius are more likely to deplete fat reserves before the end of hibernation when temperatures increase, due to generally increased body temperature (and thus energy expenditure) during hibernation, and an increase in arousal frequency.