Pilot Study of Hibernation Patterns in Noctule Bats (Nyctalus noctula): Influence of Group Size

This study investigated the influence of group size on the hibernation patterns of adult males of Nyctalus noctula during hibernation. Bats were divided into three categories (solitary, groups of six, and groups of sixteen) and nine experimental groups comprising one individual with temperature logger per group (iButton). Skin temperature (Ts) was monitored every five minutes. The results showed that bats in larger groups (the group of sixteen) entered longer and more stable torpor, with no instances of full arousal (Ts >20°C). In contrast, solitary bats exhibited more frequent arousals. All bats entered deep torpor after the first nine days. No significant differences in body mass loss were found between the groups. The findings highlight the importance of group size in reducing arousals during hibernation, and the role of social thermoregulation in conserving energy.