Welcome back to 2023’s Month of Horror and this week’s Zoopedia which simultaneously looks demonic and cute: the aye-aye. In its native Madagascar it is sometimes seen as a harbinger of death, but this is far from the actual biology of this strange primate.
Taxonomy and Evolution
Despite its appearance the aye-aye is one of around 99 species of lemur, but the aye-aye is the only member of its specific family still alive today. Aye-ayes have the scientific name Daubentonia madagascariensis, and it did share this genus with another species known as the ‘giant aye-aye’. Known for only a few pieces of jaw and tibia the giant aye-aye was around twice the size of the living aye-aye and went extinct around a 1,000 years ago. A 2018 paper hypothesised that the ancestors of aye-ayes evolved on mainland Africa like other lemurs. Their name also has an interesting theory. One of the most recent ones suggest it comes from the Malagasy for ‘I don’t know’, which was a way to get around saying the lemur’s name as they were seen as evil beings.
Biology and Behaviour
With scraggly fur, bat-ears, giant eyes, bushy tail, and long strangly fingers it is hard to picture anything like an aye-aye. Discounting the tail they reach around 360 to 440 mm (14 to 17 inches), where the tail can be double the length of the rest of the body – something they share with many other lemurs. The tail measures around 56 to 61 cm (22 to 24 inches) which helps aye-ayes balance as they traverse through the trees. Not entirely black, adult aye-ayes are a mixture of black, brown, grey, and white fur, whereas the young are a silvery colour. Aye-ayes are not sexually dimorphic, but very interestingly their nipples are on the groin. As you can tell from the dark fur and giant eyes they are nocturnal, in fact they are one of the only nocturnal primates and are the largest nocturnal primate.
I normally discuss the diet of an animal in a different section, but I will have to discuss their diet here as it is key to understanding why aye-ayes have those spindly fingers. Actually on a ball-and-socket joint, unique in the animal kingdom, the middle fingers are especially long and ends in claws. The fingers, alongside the aye-aye’s bat-like ears, allow them to use echolocation – specifically they tap tree trunks and branches searching for beetle grubs. Aye-ayes fill a similar ecological niche as woodpeckers do, except that they build their own nests instead of carving one out of a tree.
Aye-ayes are solitary but sociable. While having their own home territories aye-aye territories will often overlap, especially if those territories are held by a male and female. These territories, which can range from 40 to 215 ha, are often demarcated by scents, and fights over territory only happens between males during the breeding season. Hisses begin a fight and generally involves the teeth as damage to the fingers could prevent them from foraging. Other than that aye-ayes are shy lemurs although they sometimes do form small foraging parties. Due to their habitat and how rare they are the lifespan of an aye-aye in the wild is not entirely known, but in captivity they can live for over twenty years.
Diet and Predators
As mentioned above, aye-ayes eat the larvae of beetles that burrow in the branches and trunks of trees, using their clawed fingers to tap out the location of a grub. Using their sharp teeth they will bite into the bark to get at the grub or to bite open a hole where their finger comes in useful once again. Being on a ball-and-socket joint they can put their finger into the hole and hook a larvae with the claw on the end of the finger. They are also known for doing this with a different hole – their nose hole. Aye-ayes have been seen sticking the entirety of their spindly long finger into their nose and eating the mucus they dig out. Insect larvae are not the only thing they ever eat – fruits, bamboos, leaves, and honey also make a significant part of the lemur’s diet. Aye-ayes do not have many natural predators due to their lifestyle in the tops of trees and being nocturnal. The only major predator they have is the fossa, a member of a Malagasy carnivoran family distantly related to mongeese and cats.
Distribution and Habitat
Aye-ayes are only found on the island of Madagascar, mainly the east and north with a small population in the northwest also existing. Madagascar’s isolation from other continents for millions of years allowed it to develop a unique and strange number of plants and animals, including the aye-aye. They are found in forests with them rarely coming down from the trees, with them only leaving the treetops to go for fallen fruit or to move into a different tree. With their fragile fingers aye-ayes avoid jumping to a different tree if they can so are willing to climb down and move to a new tree.
Conservation and Threats
Aye-ayes have always been rare – from 1933 to 1957 they were believed to actually be extinct. Sadly these oddities were classified by the IUCN as being ‘Endangered’ with their numbers dropping. A common reason for why they are endangered is due to them being seen as a demonic being by several cultures in Madagascar with their presence in a village spelling doom and death. Stories range from being able to kill by pointing their finger at someone and even sneaking into people’s homes to stab them in the aorta. A very interesting paper from 2021 looked at this and found that 53% of interviewed people in 11 different villages had either a neutral or positive view of aye-ayes, and found negative perceptions on aye-ayes were held by those who had less contact with the lemur. While local people killing aye-ayes do present an issue, the paper suggests local co-operation will actually offer a way to preserve aye-ayes. Instead, habitat destruction is far more threatening to aye-ayes than local superstition. Large parts of Madagascar’s forests are being depleted to make room for intensive farming to feed demands in the global north, or for timber. Having large territories this restricts where they can live and has been the main reason for aye-aye numbers to shrink so much. It is a shame that this misunderstood animal could vanish to accomodate the desire for products.
Bibliography:
- ‘Aye-Aye’, National Geographic, [Accessed 05/10/2023]
- Louis, E.E., Sefczek, T.M., Randimbiharinirina, D.R., Raharivololona, B., Rakotondrazandry, J.N., Manjary, D., Aylward, M. & Ravelomandrato, F., ‘Aye-aye’, IUCN Red List, (07/05/2018), [Accessed 05/10/2023]
- Elizabeth Boucher, ‘Aye-aye’, Animal Diversity Web, (2007), [Accessed 05/10/2023]
- Animalogic, ‘Aye Aye: The Harbinger of Death’, YouTube.com, (15/09/2018), [Accessed 05/10/2023]
- Ben G Thomas, ‘The Aye-Aye – Animal of the Week’, YouTube.com, (25/02/2019), [Accessed 05/10/2023]
- Roger Doménico Randimbiharinirina, Torsten Richter, Brigitte M. Raharivololona, Jonah H. Ratsimbazafy, and Dominik Schüßler, ‘To tell a different story: Unexpected diversity in local attitudes towards Endangered Aye-ayes Daubentonia madagascariensis offers new opportunities for conservation’, People and Nature, 3:2, (2021), 484-498
- A.-C. Fabre, R. Portela Miguez, C. E. Wall, L. R. Peckre, E. Ehmke, and R. Boistel, ‘A review of nose picking in primates with new evidence of its occurrence in Daubentonia madagascariensis‘, Journal of Zoology, 319:2, (2022), 91-98
- Gregg F. Gunnell, Doug M. Boyer, Anthony R. Friscia, Steven Heritage, Fredrick Kyalo Manthi, Ellen R. Miller, Hesham M. Sallam, Nancy B. Simmons, Nancy J. Stevens, and Erik R. Seiffert, ‘Fossil lemurs from Egypt and Kenya suggest an African origin for Madagascar’s aye-aye’, Nature Communications, 9:3193, (2018), 1-12
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