Aye-aye  (Daubentonia madagascariensis)

The aye-aye is classified as Near Threatened (NT) on the IUCN Red List (1), and listed on Appendix I of CITES (3).

The bizarre aye-aye (Daubentonia madagascariensis) is one of the most unusual primates on the planet, so much so that it was originally classified as a rodent (2). The thick coat of the aye-aye is slate grey to brown with white flecks from the long guard hairs, which are lighter at the tip (2). The face is paler than the rest of the body with large, leathery ears and striking, yellowish-orange eyes (2). The hands of the aye-aye are also highly distinctive, having elongated, thin fingers, which bear curved, claw-like nails (4). In particular, the third digit is so extremely thin that it appears to be little more than skin and bone (2). The aye-aye is the largest nocturnal primate and has a long, bushy tail (4).

Endemic to Madagascar, the aye-aye is now known to be more wide-ranging than was previously thought, occurring in dry forests in the northwest and west of the island as well as the rainforest of the east coast (4). Introduced populations also occur on the islands of Nosy Mangabe and Aye-Aye, which is located above Mananara Nord (1). However, in all localities this species appears only at very low densities (8).

The aye-aye is found in a range of habitats from primary rainforest to dry deciduous forest (5).

The aye-aye is a nocturnal and solitary creature (5). The day is spent within a nest constructed from twigs, often located high in the crown of tall trees. Different nests are utilized on consecutive days and by different individuals (5). Male aye-ayes have large overlapping home ranges, of between 100 and 200 hectares, which encompass those of several females. Individuals scent mark their home range by rubbing parts of their neck, cheeks and rump regions onto branches (2). There is no fixed breeding season and female aye-ayes advertise their readiness to mate through distinctive calls (2). A single offspring is born after a gestation period of 160 to 170 days (2) (6) and remains within the nest for around two months before emerging (5). It is thought that females may have intervals of up to three years between births (2).

The extraordinary morphology of the aye-aye's hands are adaptations for foraging. The extended middle digit is used for a number of purposes, such as scooping the pulp out of fruit,s such as coconuts and ramy nuts (Canarium madagascariensis) (2). However, the aye-aye is probably best known for its technique of finding the insects and larvae that make up the majority of its diet. Tthe middle finger is used to tap at branches and the sound produced reveals cavities where insects might be found (5). In this respect, this primate occupies a niche that is filled by woodpeckers elsewhere (4). Once prey is located, the aye-aye tears through the wood with its strong upper incisors and then removes the prize with its long finger (5).

The aye-aye is at risk from the widespread deforestation that is threatening all of Madagascar's primates, as forests are cleared to make way for agriculture and development (2). This species exists at low densities and therefore requires large areas of suitable habitat for a viable population to exist (2). This bizarre-looking animal is the subject of many beliefs in Madagascar and in some regions is seen as an ill omen and is persecuted as a result (2). The aye-aye will feed on plantation crops such as coconuts and lychees and may therefore be treated as pests in some areas (2).

A number of protected areas within Madagascar are known to hold populations of the aye-aye (6), including Ankarana Reserve, Ranomafana National Park, Andasibe-Mantadia National Park and Nosy Mangabe Special Reserve (8). Captive breeding colonies exist at the Duke Primate Centre, North Carolina (6), at the Durrell Wildlife Conservation Trust, Jersey (7) and at London Zoo (8). Due to the elusive nature of the aye-aye, population estimates are extremely difficult, but the species is believed to be in decline (2). These concerted conservation efforts will be vital in securing the future of this intriguing and unique mammal.

To learn more about the conservation of the aye-aye visit: 

• Duke Lemur Centre – Aye-aye:
  http://lemur.duke.edu/category/nocturnal-lemurs/aye-aye
• Durrell Wildlife Conservation Trust – Aye-aye:
  http://www.durrell.org/Animals/Mammals/Ayeaye
• EDGE of Existence – Aye-aye:
  http://www.edgeofexistence.org/mammals/species_info.php?id=16