show Abstracthide AbstractThe Arctic ground squirrel (Urocitellus parryii, formerly Spermophilus parryii) is a diurnal, hibernating ground squirrel that is native to the Arctic. Adult females hibernate over winter from early August to late April, and adult males from late September to early April, at which time they can reduce their metabolism by 98% and the core body temperature from 37 °C to -2.9 °C. Torpor bouts during hibernation, like in other small hibernators, is periodically interrupted by spontaneous arousal episodes when animals raise their metabolism and body temperature returns to euthermic levels (>30 °C) for <24 hours.