Which primate is known to hibernate during the winter?

The primate known to hibernate during the winter is the fat-tailed dwarf lemur, Cheirogaleus medius. This small nocturnal lemur lives in Madagascar, where it enters prolonged dormancy during the dry season—roughly the ecological equivalent of winter, even though Madagascar is tropical.

Before hibernation, the lemur stores large energy reserves in its tail. Those reserves fuel it while it remains inactive in a tree hole, sometimes for as long as seven months. The strategy helps the animal survive a period when food and water are scarce, so its hibernation is driven more by drought than by freezing temperatures.

This fact is often confused with ordinary torpor. Some mouse lemurs and other dwarf lemurs can enter shorter periods of dormancy, but the fat-tailed dwarf lemur is the classic example of extended hibernation in a primate. Another unusual feature is that its body temperature may fluctuate with the surrounding tree-hole temperature instead of staying steadily low, unlike many temperate-zone hibernators.