Mammals
Aye-Aye
Daubentonia madagascariensis · also called aye aye
The aye-aye is the strangest primate alive — a shaggy, saucer-eyed, bat-eared lemur that hunts insect grubs the way a woodpecker does, by tapping wood and listening, then hooking them out with a witch’s-finger middle digit. In much of Madagascar it is feared as a harbinger of death.
Overview
Aye-ayes are found across Madagascar — rainforest, dry deciduous forest, mangroves, and even secondary growth and plantations — but always at low density, with individuals ranging over large territories. They are nocturnal, the largest nocturnal primate, and mostly solitary and arboreal, building a fresh spherical nest of leaves and twigs high in a tree each day to sleep in. They are quiet, cryptic, and rarely seen.
Percussive foraging
The aye-aye occupies a niche that woodpeckers fill on other continents — extracting wood-boring insect larvae from inside branches — and it does it with a unique toolkit:
- A skeletal third finger on a ball-and-socket joint. The aye-aye taps it along a branch several times a second and listens with its enormous ears for the hollow resonance of a grub tunnel.
- Rodent-like incisors that never stop growing, used to gnaw open the wood.
- The finger then goes in, bending at the joint, and hooks out the grub.
It uses the same finger to gouge open eggs, dig flesh from coconuts and ramy nuts, and lap nectar and water.
An evolutionary loner
The aye-aye is the only living member of its family, and the earliest-diverging branch of the lemur family tree, distinct for around 60 million years. Its ever-growing teeth so resembled a squirrel’s that eighteenth-century naturalists classified it as a rodent before its primate features were recognised.
Reproduction
Aye-ayes breed exceptionally slowly, producing a single infant every two to three years after about five months’ gestation. The infant is weaned at seven months but may stay with its mother for two years, and females do not breed until around three. This is the slowest reproductive rate of any lemur, and it leaves the species highly vulnerable to added mortality.
Threats and conservation
The aye-aye is Endangered and declining. Deforestation across Madagascar is the underlying driver, but the aye-aye is hit especially hard by direct killing: in many communities it is regarded as an omen of death and killed on sight, and it is also killed as a crop pest (it raids coconut, lychee, and sugarcane) and hunted for meat. Conservation efforts include forest protection, captive breeding (the Duke Lemur Center maintains a breeding colony), and, difficult but essential, work to change the cultural beliefs that lead people to kill it.
Aye-Aye: common questions
What is the aye-aye's long middle finger for?
It is a specialised feeding tool. The aye-aye taps rapidly along a branch with the thin third finger and listens, with its huge ears, for the change in sound that reveals a hollow tunnel bored by a wood-boring beetle larva. It then gnaws a hole in the wood with its chisel-like front teeth, inserts the finger — which bends at a ball-and-socket joint like a shoulder — and hooks the grub out. It uses the same finger to scoop flesh from eggs and coconuts and to drink by flicking it in and out of its mouth several times a second.
Is the aye-aye a lemur, a monkey, or a rodent?
It is a lemur — a primate — endemic to Madagascar, and it is the sole living member of its family. But its resemblances have confused people for centuries — its continuously growing incisors led early naturalists to file it with squirrels and rodents, and its odd hands and nocturnal habits set it apart from other lemurs. Genetically it is the most ancient branch of the lemur family tree, having split from the others around 60 million years ago.
Why do people in Madagascar kill aye-ayes?
In many parts of Madagascar the aye-aye is regarded as an evil omen. Its eerie appearance — glowing eyes, bat-like ears, skeletal finger — and its nocturnal habits have made it a fokon-taboo animal in local belief, and in some traditions an aye-aye pointing its middle finger at a person, or simply appearing near a village, is thought to foretell a death, so the animal is killed and sometimes displayed to ward off bad luck. This superstition, combined with its role as a crop raider, drives a lot of the killing.
Why is the aye-aye endangered?
Several pressures act together. Madagascar's forests are being cleared for farming, charcoal, and logging faster than almost anywhere on Earth, shrinking and fragmenting aye-aye habitat. The animal is killed as a bad omen and as a raider of coconut, lychee, mango, and sugarcane crops, and it is hunted for bushmeat in some regions. Its extremely slow reproduction — one infant every two to three years — means populations recover very slowly from any of these losses.