Think hibernation and you almost inevitably think bears in a snowy cave or squirrels tucked away in tree holes for a loing winter. But what about a primate? In a tropical forest? A few different types of lemur, turns out, go through seasonal hibernation, sometimes in strange places.

While it had previously been known that the western fat-tailed dwarf lemur spends seven months of the year hibernating in tree holes, until recently there was no evidence for any other primate undertaking significant hibernation periods.

A recent paper in Nature's open access journal, Scientific Reports, however, presents brand-new evidence of hibernation in two other species, the Sibree's dwarf lemur and the Crossley's dwarf lemur, both of which occur in east-central Madagascar's high altitude forests. While it may not seem as though primates would need to hibernate on a tropical island, Madagascar's mountainous regions can indeed experience temperatures that dip below freezing—a significant thermoregulatory challenge for a squirrel-sized primate. 

What's more, some of these guys do their hibernating underground, despite living the rest of their lives in the treetops. [Endless Forms]