AYE-AYE

Characteristics

Bizarre? Ugly? Freaky? No! But unique, definitely unique. The aye-aye is the world’s largest nocturnal primate and the most unusual of the lemurs. Some of its outstanding physical characteristics include incisors that grow continually, which is unique among primates; extremely large ears and extraordinary hearing; and a fluffy tail that is longer than their body. They have thick, dark fur overlaid with long, coarse, white hairs called guard hairs. When aye-ayes get excited or agitated, these guard hairs stand on end and give them the appearance of an animal twice its size. This adaptation may have evolved as a strategy to make the aye-aye look more threatening to predators, but they also use it when they are not being threatened. Perhaps their most striking feature is their fingers, which are long, thin, and flexible—and the middle finger is more like a stick than a digit, yet it is sensitive and used to find larvae under tree bark. See below for more about that fascinating adaptation!

Foods and Feeding

Insect larvae that dwell in dead trees or under the bark of live ones make up the majority of the aye-aye’s diet, along with some fruits, nuts, and seeds. And aye-ayes have evolved a specialized method to find the larvae: it’s called tap foraging. While walking along a branch, an aye-aye continuously and rapidly taps it with that amazing middle finger. Cupping its huge ears forward, it listens intently to the echoing coming from the tapping, searching for sounds that indicate a hollow space or tunnel where a grub is hiding. When it finds one, it tears off chunks of the outer bark with its tough, sharp teeth. Then the aye-aye inserts its highly flexible third finger into the hole, hooks the grub with the tip of the finger, and pulls it out to eat it.

Behavior

Aye-ayes are nocturnal, solitary foragers that spend most of the night feeding and traveling through the forest canopy. The majority of their time is spent in the trees, but traveling on the ground is fairly common. During the day, aye-ayes sleep in spherical nests they make with leaves and branches. They may use a nest for multiple days in a row or leave it and return later while they make new nests elsewhere. Most nests are occupied by only one adult or a mother and her young.

Males have large home ranges, between 250 to 500 acres (100 and 200 ha), while the home ranges of females are much smaller, usually between 75 to 130 acres (30 and 50 ha). A male’s territory can overlap that of several different males. Although encounters between neighboring males are rare, they may lead to fights. Female ranges do not overlap with those of other females, but they always overlap that of at least one male.

Aye-ayes have a few vocalizations. One is a long “creee” scream call they make in situations of alarm or agitation. A quieter “gnnoff” sound is a peaceful call when aye-ayes come together, particularly during feeding. Other sounds include sneezes, snorts, and whimpers. Aye-ayes also use olfactory signals, such as depositing urine around their nests and feeding branches to let other aye-ayes know they’re around.

Reproduction and Life Cycle

Aye-aye females reach sexual maturity at around two years old, and, unlike other lemurs, aye-ayes may breed at any time of year. A female will mate only when she is ready to accept a male, however. She will attack an approaching male if she is not receptive. If she is interested, they touch noses and lick each other’s mouths, and they may chase each other along the canopy. Infants are born with dark fur but have green instead of yellow eyes and soft, floppy ears. Young aye-ayes spend most of their time in their mother’s nest, and she tends to stay nearby, feeding on fruits and insects that are close. She will even open nuts for her youngster to eat in the nest.  

The learning process of young aye-ayes is a vital part of their development. They learn many skills and behaviors by observing and mimicking their mother. They also have to learn the specialized tapping hunting technique, which takes some time to master. The adult teeth come in when they are four months old, and they then stop depending on their mother’s milk for food but still stick close to her for protection. By the time aye-ayes are nine months old, they can travel without their mother, but they may still stay with her if she doesn’t have a new offspring.  

Conservation and Threats

Once considered one of the most endangered mammals in the world, the aye-aye has been shown to be more widely distributed than originally thought. Findings indicate that the aye-aye is distributed along the east coast and in the northwestern forests of Madagascar, but the population is spread out, so seeing one in the wild remains a rare event.

The aye-aye’s main threats are loss of habitat and hunting by humans. Unlike many lemur species that are hunted for food, aye-ayes are sometimes killed as perceived pests in agricultural areas. Traditionally, villagers have seen the aye-aye as an evil omen, or “fady,” to be killed on sight to avoid bringing bad luck. Fortunately, this perception is now changing. Currently, aye-ayes are found in at least 16 protected areas, and several of these appear to have healthy populations. Protection, understanding, and awareness are key to ensuring that these extraordinary lemurs continue to climb, tap, and nest in Madagascar’s forests.