In well-insulated tree holes, which lemur keeps a fairly constant body temperature during hibernation?

The fat-tailed dwarf lemur keeps a fairly constant body temperature during hibernation when it shelters in a well-insulated tree hole.

The species, Cheirogaleus medius, is native to Madagascar and is famous for being the first tropical mammal—and the only primate—shown to undergo extended hibernation. Its dormancy is linked less to freezing winter temperatures than to Madagascar’s dry season, when food and water become difficult to obtain.

Before dormancy, the lemur stores large energy reserves in its tail. That fat supports months of torpor, which may last up to seven months. The tree hole is crucial: in a well-insulated cavity, the animal can maintain a comparatively stable body temperature, but in a poorly insulated hole its temperature fluctuates with the surrounding air.

This is an easy species to confuse with other lemurs. Indris, aye-ayes, and ring-tailed lemurs have distinctive adaptations of their own, but the fat-tailed dwarf lemur is the standout example of prolonged primate hibernation. It may also experience REM sleep during torpor, an unusual feature among hibernators.