Bioenergetic benefits of huddling by deer mice (Peromyscus maniculatus).

Both short photoperiod and communal social living conserve metabolic energy by deer mice held in thermal neutral ambient temperatures. Initial socialization was energetically more costly than solitary living, but huddling behaviors reduced thermal conductance and mass specific metabolic rate by 30% within 5 days. While short photoperiod reduced metabolic energy expenditure by decreasing thermoregulatory demand, huddling mediated behavioral conservation was achieved with hyperthermic core temperatures.