Aye-aye

The aye-aye (, Daubentonia madagascariensis) is a long-fingered lemur, a strepsirrhine primate native to Madagascar with rodent-like teeth that perpetually grow and a special thin middle finger that they can use to catch grubs and larvae out of tree trunks. It is the world's largest nocturnal primate. It is characterized by its unusual method of finding food: It taps on trees and listens for echoes that signal hollows inside them, which are often infested by grubs, then gnaws holes into the wood using its forward-slanting incisors to create a small hole into which it inserts its narrow middle finger to pull the grubs out. This foraging method is called percussive foraging, and takes up 5–...

The aye-aye lives primarily on the east coast of Madagascar. Its natural habitat is rainforest or dry deciduous forest, but many live in cultivated areas due to deforestation. Rainforest aye-ayes, the most common, dwell in canopy areas, and are usually sighted above 70 meters altitude. They sleep during the day in nests built from interwoven twigs and dead leaves up in the canopy among the vines and branches.

Madagascar

The aye-aye is an omnivore and commonly eats seeds, nuts, fruits, nectar, plant exudates and fungi, but also xylophagous, or wood boring, insect larvae (especially cerambycid beetle larvae) and honey. Aye-ayes tap on the trunks and branches of trees at a rate of up to eight times per second, and listen to the echo produced to find hollow chambers. Studies have suggested that the acoustic properties associated with the foraging cavity have no effect on excavation behavior. Once a chamber is found, they chew a hole into the wood and get grubs out of that hole with their highly adapted narrow and bony middle fingers. The aye-aye begins foraging between 30 minutes before and three hours after sunset. Up to 80% of the night is spent foraging in the canopy, separated by occasional rest periods. 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 travel up to 4 km (2+1⁄2 mi) a night. Though foraging is usually solitary, they occasionally forage in groups. Individual movements within the group are coordinated using both vocalisations and scent signals. Throughout the wet season, the aye-aye is known to spend up to 20% of its time feeding on the nectar of Ravenala madagascariensis. Other than Homininae, it is the only known primate to possess the (A294V) mutation on the encoding gene for alcohol dehydrogenase class IV enzyme, which is known to drastically improve the enzyme's efficiency. A 2016 study showed that the aye-aye is able to differentiate between different alcohol concentrations in nectar and showed a clear preference towards the higher concentrations. This suggests that in the wild, it is able and likely to consume fermented nectar and that its ability to metabolize alcohol might have been an evolutionary advantage.

The aye-aye is a nocturnal and arboreal animal meaning that it spends most of its life high in the trees. Although they are known to come down to the ground on occasion, aye-ayes sleep, eat, travel and mate in the trees and are most commonly found close to the canopy where there is plenty of cover from the dense foliage. During the day, aye-ayes sleep in spherical nests in the forks of tree branches that are constructed out of leaves, branches and vines before emerging after dark to begin their hunt for food. Aye-aye are solitary animals that mark their large home range with scent. The smaller territories of females often overlap those of at least a couple of males. Male aye-ayes tend to share their territories with other males and are even known to share the same nests (although not at the same time), and can seemingly tolerate each other until they hear the call of a female that is looking for a mate. Mating season extends throughout the year, with females typically starting to breed at the age of three or four. They give birth to one offspring every two to three years. During the period of parenting, a female becomes the dominant figure over males, likely to secure better access to food while caring for her young. The infant remains in a nest for up to two months before venturing out, but it takes another seven months before the young aye-aye can maneuver the canopy as skillfully as an adult.

longest observed 32.3 years.

The conservation of this species has been aided by captive breeding, primarily at the Duke Lemur Center in Durham, North Carolina. This center has been influential in keeping, researching and breeding aye-ayes and other lemurs, including how they develop through infancy. They have also revolutionized the understanding of the aye-aye diet. Jersey Zoo also plays a big role in the conservation of the species. After importing six aye-ayes from the wild in 1990, they achieved the world's first captive breeding in 1992. They also keep the international studbook of the species and manage the European breeding programmme.

A full-grown aye-aye is typically about 60 centimetres (2 feet) long with a tail longer than its body. The species has an average head and body length of 36–43 cm (14–17 in) plus a tail of 56–61 cm (22–24 in), and weighs around 2 kilograms (4 pounds). Young aye-ayes typically are silver colored on their front and have a stripe down their back. However, as the aye-ayes begin to reach maturity, their bodies will be completely covered in thick fur and are typically not one solid color. On the head and back, the ends of the hair are typically tipped with white while the rest of the body will ordinarily be a yellow and/or brown color. Among the aye-aye's signature traits are its fingers. The third finger, which is much thinner than the others, is used for extracting grubs and insects out of trees, using the hooked nail. The finger is unique in the animal kingdom in that it possesses a ball-and-socket metacarpophalangeal joint, which can reach the throat through a nostril and is used for picking one's nose and eating mucus (mucophagy) harvested from inside the nose. The aye-aye has also evolved a sixth digit, a pseudothumb, to aid in gripping. The complex geometry of ridges on the inner surface of aye-aye ears helps it to accurately focus not only echolocation signals by tapping its finger, but also to passively listen for other sounds produced by prey. These ridges can be regarded as the acoustic equivalent of a Fresnel lens, and can be seen in a large variety of unrelated animals, such as lesser galago, bat-eared fox, mouse lemur, and others. Females have two nipples located in the region of the groin. The male's genitalia are similar to those of canids, with a large prostate and long baculum.

The aye-aye was thought to be extinct in 1933, but was rediscovered in 1957. In 1966, nine individuals were transported to Nosy Mangabe, an island near Maroantsetra off eastern Madagascar. Recent research shows the aye-aye is more widespread than was previously thought, but its conservation status was changed to endangered in 2014. This is for four main reasons: the aye-aye is considered evil by local cultures, and is killed as such. The forests of Madagascar are declining in range due to deforestation. Local farmers will kill aye-ayes to protect their crops; aye-aye poaching is another major issue. However, there is no direct evidence to suggest aye-ayes pose any legitimate threat to crops and therefore are killed based on superstition. As many as 50 aye-ayes are in zoological facilities worldwide.

The genus Daubentonia was named after the French naturalist Louis-Jean-Marie Daubenton by his student, Étienne Geoffroy Saint-Hilaire, in 1795. Initially, Geoffroy considered using the Greek name Scolecophagus ("worm-eater") in reference to its eating habits, but he decided against it because he was uncertain about the aye-aye's habits and whether other related species might eventually be discovered. In 1863, British zoologist John Edward Gray coined the family name Daubentoniidae. The French naturalist Pierre Sonnerat was the first to use the vernacular name "aye-aye" in 1782 when he described and illustrated the lemur, though it was also called the "long-fingered lemur" by English zoologist George Shaw in 1800—a name that did not stick. According to Sonnerat, the name "aye-aye" was a "cri d'exclamation & d'étonnement" (cry of exclamation and astonishment). However, American paleoanthropologist Ian Tattersall noted in 1982 that the name resembles the Malagasy name "hai hai" or "hay hay", (also ahay, aiay, haihay) which refers to the animal and is used around the island. According to Dunkel et al. (2012), the widespread use of the Malagasy name indicates that the name could not have come from Sonnerat. Another hypothesis proposed by Simons and Meyers (2001) is that it derives from "heh heh", which is Malagasy for "I don't know". If correct, then the name might have originated from Malagasy people saying "heh heh" to avoid saying the name of a feared, magical animal.