Aye-aye (Daubentonia madagascariensis): size, diet and habitat

The aye-aye, Daubentonia madagascariensis, is a nocturnal lemur endemic to Madagascar¹, where it has been recorded along the western region and central to the eastern coast, at a population density the New England Primate Conservancy calls surprisingly low. It is the only living member of its family, Daubentoniidae, and is best known for large incisors that grow continuously, similar to a rodent’s², and an extremely thin third finger³ it uses to dig out seeds and insect larvae.

What does an aye-aye look like?

Males weigh about 2.62 kg and females about 2.57 kg, and Animal Diversity Web gives a head-body length of 36 to 44 cm¹, with a bushy tail of 44 to 53 cm, longer than its body. The coat is dark brown or black, with hairs tipped in white⁴, and the chest, throat and face are paler than the body. It has a short snout, a prominent pink nose and large ears², and yellow-orange or sandy-brown eyes surrounded by dark rings³.

An aye-aye has only 18 teeth in total, where a typical lemur has 30 to 36, and its large, curved, chisel-like incisors grow continually throughout life, which the San Diego Zoo Wildlife Alliance calls uncommon in primates. The third finger is extremely thin and skeletal in appearance, with a ball-and-socket joint and 360° of movement³.

Where do aye-ayes live?

Aye-ayes live in primary and secondary rainforest, deciduous forest and cultivated plantations, and occasionally in dry scrub forest and mangrove forest, and spend most of their time in the upper two levels of the canopy¹. The New England Primate Conservancy notes they need high canopies of 10 to 15 m where they can build nests, and hardwood trees that provide enough fruit and insects for food. Some aye-ayes live in or near plantations, where they may subsist on coconuts².

Home ranges differ sharply by sex: females hold 30 to 40 hectares against 125 to 215 hectares for males, whose ranges overlap each other by 40 to 75 percent¹.

What do aye-ayes eat?

The aye-aye is omnivorous. Animal Diversity Web lists wood-boring insect larvae, especially cerambycid beetle larvae, as an important part of the diet, alongside favoured plant foods such as breadfruit, banana, coconut and ramy nuts¹, while bamboo, traveller’s-tree nectar, lychees and mangoes may also be eaten. The San Diego Zoo Wildlife Alliance puts seeds, nectar, cankers and insect larvae at 90% of the diet⁴.

To find larvae, an aye-aye taps on branches with its long third finger and listens for vibrations that indicate cavities or moving grubs, then breaks through the bark with its teeth and hands and digs the prey out with its long fingers. Young aye-ayes learn this technique by watching their mothers² and then practising through trial and error. In the wild an aye-aye eats roughly 240 to 342 kilocalories a day¹.

How do aye-ayes live?

Aye-ayes are nocturnal and solitary, though they may forage in parties of two or three. Activity begins half an hour before sunset and continues to 3 hours after sunset¹, and by day animals sleep in bowl-shaped nests built from small tree branches and vines, more than 9 m from the ground; they frequently move from one location to another and may build many nests. They travel quadrupedally and climb horizontal branches and vertical tree trunks² with their long, clawed fingers, but hesitate to jump across gaps of more than 2 m⁵.

Male ranges overlap, while there is no overlap in female ranges, and males regularly visit the ranges of females; brief encounters between males are often agonistic, ending in chases, fights or one animal displacing the other. Calls include a distinctive scream indicating aggression and a brief descending whimper heard in competition over food, along with screeches, pleas, sneezes and snorts; animals also deposit urine around the nest, on the ground or on oblique branches⁵. Little is known about predation: aye-ayes may be prey for fossas¹, and snakes and raptors may prey on infants and young⁴.

How do aye-ayes reproduce and how long do they live?

The San Diego Zoo Wildlife Alliance describes reproduction as non-seasonal, while Animal Diversity Web gives a mating period from October to February¹, with infants typically born between February and September. Males cluster around a female, females mate with multiple partners, and intromission lasts nearly an hour, 55 to 65 minutes. Gestation runs 158 to 172 days, with a mean of 167, and a female gives birth to one infant weighing 90 to 140 g⁴. The father does not assist with infant care; the infant stays in or near the nest for 2 to 3 months after birth, and in managed care infants were weaned by about 6 to 7 months. Sexual maturity comes between 8 and 36 months of age, and in the wild the interval between births is 2 to 3 years⁶.

Lifespan in the wild is unclear², but aye-ayes can live in captivity for more than 20 years, and a captive female lived to 23.3 years¹.

Is the aye-aye endangered?

The IUCN lists the aye-aye as Endangered, under Red List version 2022.2⁷. Little is known about its population size: the New England Primate Conservancy estimates between 1,000 and 10,000 individuals left in the wild, and the San Diego Zoo Wildlife Alliance says the species is thought to occur at low densities, with sharp population declines since the 1980s. Loss of habitat is one of the main threats: trees are harvested for construction, among them Intsia bjuga and Canarium madagascariensis, whose seeds are dietary staples for the species⁸. Some locals also kill aye-ayes as pests that destroy agricultural trees, and in local lore an aye-aye is said to bring ill fortune to those who see it².

The species is listed on CITES Appendix I and occurs in 13 national parks, 7 nature reserves and 13 special reserves, though population sizes in these areas are unknown. A population was established on Nosy Mangabe island in 1966/1967 from 9 founding individuals⁸, in an attempt to help preserve the species, and another on Ile Roger.

Similar species

• Ring-tailed lemur (Lemur catta): a lemur that lives in troops of 15 to 20 animals, told apart from the solitary aye-aye by its tail with black and white rings from stem to tip and its gray-to-brown coat with, typically, a white face mask, with black outlining the eyes and nose⁹.
• Indri (Indri indri): a diurnal lemur much larger than the aye-aye, at 7 to 10 kg, head-body length 60 to 90 cm, with a tail only 5 to 6 cm long¹⁰ against the aye-aye’s bushy tail of 44 to 53 cm³.