aye-aye is a lemur, a strepsirrhine primate native to Madagascar that combines rodent-like teeth and a special thin middle finger to fill the same ecological niche as a woodpecker. It is the world's largest nocturnal primate, and is characterized by its unusual method of finding food; it taps on trees to find grubs, then gnaws holes in the wood and inserts its narrow middle finger to pull the grubs out. The only other animal species known to find food in this way is the striped possum. It usually sticks to foraging in its own personal home range, or territory. The home ranges of males often overlap, and the males can be very social with each other. Female home ranges never overlap, though a male's home range often overlaps that of several females. The male aye-ayes live in large areas up to 80 acres (320,000 m2), while females have smaller living spaces that goes up to 20 acres (81,000 m2). Regular scent marking with their cheeks and neck is how aye-ayes let others know of their presence and repel intruders from their territory. The monkey-like body of the aye-aye enables it to move vertically with ease. It climbs trees by making successive vertical leaps, much like a squirrel. Horizontal movement is more difficult, but the aye-aye rarely descends to jump to another tree, and can often cross up to 4 km (2.5 mi) a night.
Infants are fully dextrous within a month of birth.
aye-aye lives primarily on the east coast of Madagascar. Its natural habitat is rainforest or deciduous forest, but many live in cultivated areas due to deforesting. Rainforest aye-ayes, the most common, dwell in canopy areas, and are usually sighted upwards of 700 meters altitude.