ABSTRACT
Marmots (Marmota, 14 species) typically live at high altitude or latitude and hibernate in extended family groups. Winter is a major cause of mortality in marmots. In this chapter, the author provides data for winter mass loss and mortality in highly social alpine marmots. He investigates the alpine marmot's thermoregulatory response to low temperature and the influence of group members on individual thermoregulatory behavior using data from a telemetry study of hibernation in the natural habitat. The most remarkable feature of group hibernation in alpine marmots is the synchrony of arousal episodes among group members. In such groups DML of subordinate individuals decreased with increasing group size. This implies a reduction in individual energy expediture, most likely achieved by decreased thermal conductance due to huddling of group members. Several lines of evidence suggested that juveniles were warmed by huddling group members.
