No energetic benefits from sociality in tropical hibernation

Mammals generally profit from social thermoregulation, and the primary benefit of sociality during hibernation is thought to be the reduction of metabolic demands during periodic arousals. It has even been postulated that the energetic advantages during hibernation might have been the driver for the evolution of sociality in some mammal species. As the necessity to show arousals and the concurring energetic costs depend on the temperature regime in the hibernacula, we tested whether this is also a plausible scenario in tropical hibernators such as the Malagasy lemur Cheirogaleus medius, with comparatively high and often fluctuating temperature regimes in their hibernacula. To this end, we studied group composition and energy budgets (skin temperature patterns, metabolic rate) over three hibernation and activity seasons in a total of 53 free-ranging C. medius. Our results show that C. medius mostly occupied tree hollows solitarily during hibernation, contrary to the active season, and th...