Fig. 1.
Body temperature (Tb) of a laboratory-housed 13-lined ground squirrel (Ictidomys tridecemlineatus) over ∼8 mo. The hibernation label identifies the winter heterothermic period and the annual cycle of this species is completed by a spring-fall active period. The physiological state at sampling (n = 8) over the year are indicated by the abbreviations. SA, summer active; Ent, entering torpor; ET, early torpor; LT, late torpor; Ar, early arousing; LAr, late arousing; IBA, interbout aroused, SD, spring dark.