Aye-aye: the strangest primate

With a peculiar appearance and way to find food, the aye-aye is perhaps the rarest primate that exists. It is also rare for its distribution and specimens: it is endemic to Madagascar and it is in risk of extinction. Find out in this post why the aye-aye is special.

THE AYE-AYE IS A PROSIMIAN

The aye-aye is the only species of the Daubentoniidae Family. It was believed to have been extinct until its rediscovery in 1957. Although it is hard to believe, the aye-aye is a primate like us. Some authors consider it a type of lemur.

Aiye-aye (Daubentonia madagascariensis). Photo: Frans Lanting

Its strange name is believed to come from the Malgasy expression “heh heh“, which means “I do not know”, to avoid naming it as it is considered as an animal that represents evil according to some traditions.  “Hai hai” or “hay hay” is also a common name on the island of Madagascar that could have given the animal its name.

Because it is a prosimian, the oldest group of primates, it has particular carachteristics. The prosimians are characterized by:

  • Claws instead of nails (they have at least one nail)
  • Long snout with moist nose. They are the primates with the greater sense of the smell
  • Bigger lateral orientation of the eyes than other primates. These are large and have good night vision
  • Mobile hearing pavilions
  • They have the lower cerebral proportion of primates

If you want to know more about classification and characteristics of primates, you can visit the post Who are the hominids?

APPEREANCE AND BEHAVIOR

The aye-aye has a black-brown coarsed fur covered by white hairs as  a protection. It has a leafy tail as long as its own body. They measure up to 40 cm and weigh up 2.5 to 3 kg, making them the largest nocturnal primates.

Its eyes and auditory pavilions are large and its fingers are slender, with claws in all of them, which allows them to hang from the branches. It is therefore exclusively arboreal. To climb it performs small vertical jumps like squirrels do, and it avoids treading the ground of the rainforest in which it lives, in the North and East of Madagascar.

Front view of aye-aye and its claws. Photo: Dani Jeske

They have nocturnal and solitary habits and they spend the day resting between the junction of the branches or in a kind of nest made of branches and leaves. These nests have the appearance of spheres with an entrance hole, they are located between the branches of large trees and are occupied by successive aye-ayes, they are never shared.

DIET

The aye-aye feed mainly on seeds of Canarium spp, a tree, which determines its distribution. It also eats fruits, including coconut pulp, other seeds and fungi.

But they are also attracted to insect larvae, and their way of finding them is almost exclusive: it gives small strokes on the bark of the trees with their thin third finger (up to 8 times/second), and then it listens the presence of larvae inside the hollow chambers, in a way similar to echolocation  (it is the only primate that uses echolocation).

 Detail of lmano del Aye-aye, with the thin third finger and the long fourth finger. Photo by Mark Carwardine
Aye-aye hand detail, with the slender third finger and the long fourth finger Photo: Mark Carwardine

Like the woodpecker, which also feeds on larvae from within the trees, the aye-aye uses the frontal teeth to chew the bark. Its frontal teeth are always growing as rodent teeth do, and with the third or fourth finger, which is the longest and with a double joint, extracts the larvae. Here’s how aye-aye’s do it in this short video:

This method of finding food is known as percussive foraging. The only other animal known to use this strategy is the stripped possum  (Dactylopsila trivirgata), an Australian marsupial.

Stripped possum. Photo: Peter Bray
Stripped possum. Photo: Peter Bray

REPRODUCTION

Although they are solitary, there is evidence that aye-ayes also feed on tandem and exhibit different relationships between animals of the same sex (Sterling and Richard 1995). The territories of different males can overlap each other, as well as the terriotories of several females. These territories are marked with scents.

Females are fertile at 3-4 years old and can give birth every 2-3 years (Petter and Peyrieras 1970). There is no season of mating and after gestation a single young is born.

Aye-aye de un día de vida siendo pesado dentro de un programa de cría en cautividad. Foto: David Haring
One year old aye-aye being weighed within a captive breeding program. Photo: David Haring

THREATS AND CONSERVATION

Aye-aye is considered by the IUCN Red List as endangered. The trend of the population is decreasing, and in the last 30 years more than half of it has disappeared. The main cause is the decline and degradation of their habitat, as well as the exploitation of the forest through unsustainable ways of hunting. These causes have not ceased and they are not easily reversible, so it is estimated that in 10-20 years more than 50% of the population will disappear. If you want to know more about the threats to Madagascar, visit Madagascar, a paradise in danger.

Distribución del Aye-aye en Madagascar, África. Fuente
Distribution of aye-aye in Madagascar, África. Source

In addition to habitat destruction and its hunting as food, it is also killed in some areas as a bad omen, an evil incarnation or a pest for crops (eg coconut).

Aye-aye cazado y colgado para que los viajeros se lleven su espíritu maligno, según algunas tradiciones malgasias. Foto: Thomas Althaus
Aye-aye hunted and hung for travelers to take away their evil spirit, according to some Malagasy traditions. Photo: Thomas Althaus

Some populations are in protected areas within National Parks and reserves. There are also captivity breeding programs to study the aye-aye and its subsequent reintroduction of the species in their habitat, which began in the 60s, since their populations are fragmented and with low density of individuals. Even so, the second generation has not succeeded in reproducing in captivity.

It is difficult to establish the number of individuals, which have evasive and nocturnal habits. Their presence is assumed by the marks that they leave in the trees, although a single individual can leave several marks. It is suspected that the aye-aye has the least genetic diversity of all lemurs. More research and census of aye-aye are needed to understand more about its population dynamics and biology.

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY

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