Aye-aye: the bizarre life of the world’s largest nocturnal primate

Each Wednesday, One Earth’s “Species of the Week” series highlights a relatively unknown and fascinating species to showcase the beauty, diversity, and remarkable characteristics of our shared planet Earth.

Only after the sun has set on the island of Madagascar and the jungle is covered in the cloak of night, can you spot one of the most peculiar of our hominid cousins. With rounded ears like a bat, bulging eyes of an owl, teeth of a rat, dexterous fingers of a raccoon, and a black, bushy tail similar to a squirrel’s — although much larger — the aye-aye is quite the product of evolution. A member of the lemur family, it is the world’s largest nocturnal primate and its features highlight it’s nocturnal life. 

Most primates, including humans, are highly vision-oriented which is why any ordinary member of our family species would hunt and gather for food during the day. Aye-ayes are much more equipped to sense by sound, touch, and scent. This is characterized by their unusual method of finding food. Using their overexaggerated ears and middle finger, which is even lankier than their other fingers, they tap on branches to find hollow areas where grub might lie — much like the woodpecker. They then use their slanted, rodent-like incisors, which never stop growing in their lifetime, to gnaw into the bark and punch a hole. Through this hole, they stick their specialized and muscular fourth finger to pull out their dinner with it’s pointed claw. This is called percussive foraging and the other only known animal to do this is the striped possum.

Aye-ayes are relatively small, measuring only up to a meter long including their tail which makes up half their body length. They spend their lives in the trees and avoid coming down to the forest floor except on very rare occasions. Their days are spent curled up in a ball in their nests of leaves and vines that appear as closed circles with single entry holes, nestled between the forks of rainforest branches. Generally solitary, the aye-aye marks its territory with scent, but males can seemingly tolerate each other as their territories overlap and they are often spotted in the same area, of course, until they hear the call of a female. Females are the dominant sex in aye-ayes as the males are unable to leave until copulation has been completed. Mating takes about an hour and one female has a single baby every two to three years. 

Throughout the island, a variety of other lemurs can be found. There’s the red-ruffed lemur, known for its colored fur, or the ring-tailed lemur, known for its infamous coat pattern. Where then does the aye-aye derived its name from, as the “long-fingered lemur" coined by English zoologist George Shaw in 1800 did not stick?  “I don’t know,” that is what "heh heh" translates to in English from Malagasy. However, the Malagasy people say "heh heh" not only because of the animal’s unique features and lifestyle, but also to avoid saying the name of the creature they view with superstition.

Many people native to Madagascar consider the aye-aye a bad omen and often kill them on sight. Superstition, along with how infrequent aye-ayes reproduce, are two causes of their dwindling numbers. Habitat destruction due to land development across the island has further exasperated the problem. The aye-aye population is at-risk. Fifty percent of the island's population has been eliminated in the last thirty years and that figure is set to increase by another 50% in the next one to two decades. Today, they are protected by law, and furthering the education of the species can aid in the conservation of this unique animal.