Mechanisms of social thermoregulation in hibernating Alpine marmots (Marmota marmota)

Group-hibernating Alpine marmots maintain close body contact to other group members during both deep torpor and euthermic intervals. Analyzing telemet rically recorded body temperature (T-b) profiles of 64 free-living marmots we found that rates of hear loss were independent of individual body mass. Serial correlation coefficients for pairwise comparisons of T-b patterns in dicated that the time course of changes between torpor and periodic arousal s was generally well synchronized within groups, with territorials arousing significantly earlier than other group members. Thr degree of group synchr ony was the most important factor influencing winter mass-loss. However, gr oup synchrony was impaired in the presence of juveniles. Juveniles frequent ly displayed delayed warm-ups and appeared to passively gain heat from clos e body contact to warmer adults. While reduced group synchrony is disadvant ageous for adults, it can be calculated that juveniles have a net energetic al benefit.