Aye-aye  (Daubentonia madagascariensis)

The bizarre aye-aye 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 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 prominent, yellowish-orange eyes (2). The hands are the most striking feature of this animal; the elongated, thin fingers have curved, claw-like nails (4) and the third digit is extremely thin so 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). However, in all localities it appears only at very low densities (8).

Found in a range of habitats from primary rainforest to dry deciduous forest (5).

Aye-ayes are nocturnal and solitary creatures (5). The day is spent within a nest constructed from twigs and often located high in the crown of tall trees; different nests are utilized on consecutive days and by different individuals (5). Males 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 females 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 fruits 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; the middle finger is used to tap at branches and the sound produced reveals cavities where insects might be found (5). In this respect, these primates occupy a niche that is filled by woodpeckers elsewhere (4). Once prey is located, aye-ayes tear through the wood with their strong upper incisors and then remove the prize with their long finger (5).

Aye-ayes are 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). These bizarre-looking animals are the subject of many beliefs in Madagascar and in some regions are seen as ill omens and are persecuted as a result (2). Aye-ayes will feed on plantation crops such as coconuts and lychees and may therefore be treated as pests in some areas (2).

Aye-ayes have been recorded from a number of protected areas within Madagascar (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 Jersey Wildlife Preservation Trust (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.

For more information on the aye-aye see:

• Primate Info Net:
  http://www.primate.wisc.edu/pin/factsheets/daubentonia_madagascariensis.html
• Garbutt, N. (1999) Mammals of Madagascar. Pica Press, Sussex
• Duke University Lemur Centre:
  http://lemur.duke.edu/animals/ayeaye/print.php

Authenticated (2/7/03) by Nick Garbutt.