Daubentonia madagascariensis
aye-aye

Daubentonia madagascariensis, commonly known as the aye-aye, is endemic to Madagascar. Aye-ayes can be found widely distributed across the island. (Quinn and Wilson, 2004)

Daubentonia madagascariensis can be found in a wide variety of environments including primary and secondary rainforest, deciduous forest, cultivated plantations, and occasionally dry scrub forest and mangrove forest. They spend most of their time in the upper two levels of the canopy. (Ancrenaz, Lackamancrenaz, and Mundy, 1994; Quinn and Wilson, 2004)

Aye-ayes have a head-body length from 360 to 440 mm and a long bushy tail. The coat is long, coarse, and either dark brown or black in color, with scattered white guard hairs. The face and throat are pale gray and facial features include yellow-orange or sandy brown eyes surrounded by dark markings, large triangular ears, a short snout, and a pink nose. There is no significant sexual dimorphism between males and females. (Feistner, Sterling, and Dodo, 1995; Quinn and Wilson, 2004; Soligo, 2005)

Aye-ayes have highly specialized digits. The third digit of the hand is slender, elongated, and flexible, and is especially important in feeding behaviors. Aye-ayes have a dental formula of I:1/1, C:0/0, PM:1/0, M:3/3. The incisors are large and ever-growing, with enamel coating only the anterior surface. There is a large diastema present in both the upper and lower jaws. (Feistner, Sterling, and Dodo, 1995; Quinn and Wilson, 2004; Soligo, 2005)

A captive female lived to an age of 23.3 years. (de Magalhães, 2007)

Aye-ayes are nocturnal and solitary. Most of the daytime is spent sleeping in an ovular nest located in the upper two levels of the canopy. Individuals tend to sleep singly, but may share a nest on occasion, and nests can be occupied by different individuals at different times. Activity begins half an hour before sunset and continues to 3 hours after sunset. Males usually become active before females. During the night, aye-ayes spend their time alternately foraging, feeding, and grooming. Aye-ayes may assemble in foraging parties of 2-3 individuals. Aye-ayes often cling upside down on branches and can rest vertically or horizontally. (Ancrenaz, Lackamancrenaz, and Mundy, 1994; Krauker, Lemlin, and Schmidt, 2002; Quinn and Wilson, 2004)

Aye-ayes are able to make use of a wide range of locomotor methods including arboreal quadrupedalism, leaping, and head-first descent. The forces of locomotion can be potentially harmful to the long, slender digits of the aye-aye, so individuals may curl their fingers or shift their bodies to carry more weight caudally. These techniques help prevent damage to their delicate fingers. The powerful, opposable big toe, robust shoulder girdle, and strong humerus are features that help enable head-first descent. Aye-ayes are able to use wide and narrow, as well as vertical, horizontal, and oblique branches as supports in locomotion. (Ancrenaz, Lackamancrenaz, and Mundy, 1994; Krauker, Lemlin, and Schmidt, 2002; Quinn and Wilson, 2004)

Home Range

Individuals have their own ranges, which are scent marked and possibly marked by distinctive tooth impressions made by powerfully biting into tree bark. Male ranges are larger than female ranges, and each male range overlaps with at least one female range. Furthermore, male ranges overlap between 40 and 75 percent, and these shared spaces may be occupied by numerous individuals simultaneously. Female home ranges are from 30 to 40 hectares in area, while male home ranges are from 125 to 215 hectares. (Ancrenaz, Lackamancrenaz, and Mundy, 1994; Mittermeier et al., 2006; Quinn and Wilson, 2004)

Aye-ayes communicate using a number of vocalizations. A distinctive scream indicates aggression, and a closed mouth version of this scream can indicate protest. A brief descending whimper is heard in connection with competition over food resources. A “tiss” sound serves as a response to the appearance of humans or lemurs, and a “hai-hai” vocalization can be heard during attempts to flee from captors. (Quinn and Wilson, 2004)

To fulfill basic needs for growth and maintenance, aye-ayes require a diet rich in fats and proteins. In the wild roughly 240 to 342 kilocalories are consumed daily and the calorie intake is steady throughout the year, although it is slightly lower in the cold season relative to the hot, wet, and dry seasons. Aye-ayes have a varied diet consisting of fruits, nuts, and plant exudates. Breadfruit, banana, coconuts, and ramy nuts are among the favored foods, but bamboo, nectar from the traveler’s tree, lychees, and mangoes may also be consumed. Aye-ayes use their specialized third digit to pierce the outer skin of fruits and scoop out the contents. (Dierenfeld, Ashbourne, and Feistner, 1994; Erickson et al., 1998; Erickson, 1995; Kaufman, Ahrens, and Laidlaw, 2005; Quinn and Wilson, 2004)

Xylophagous, or wood boring, insect larvae make up another important component of the aye-aye diet, especially cerambycid beetle larvae. Aye-ayes have several derived features and a unique percussive foraging method to detect the presence of these larvae in trees. The specialized third digit is used to tap on wood in search of hollow spaces below the surface of the bark. There are conflicting views on whether aye-ayes can detect the sound of reverberations in these cavities or whether they can detect breaks in the integrity of the wood. Once a cavity is found, the aye-aye uses its large, procumbent incisors to gnaw through the bark and extracts the larvae with its long and slender third digit. There are several other features that may be related to foraging behaviors. These include an enlarged frontal cortex and an increased volume of the olfactory lobe, as well as large, naked ears, which enhance hearing. (Dierenfeld, Ashbourne, and Feistner, 1994; Erickson et al., 1998; Erickson, 1995; Kaufman, Ahrens, and Laidlaw, 2005; Quinn and Wilson, 2004)

Aye-ayes may be prey for fossas, Cryptoprocta ferox, one of Madagascar’s largest carnivores. However, little is known about predation on aye-ayes. Their nocturnal and arboreal habits may protect them from much predation. (Quinn and Wilson, 2004)

Aye-ayes may help to disperse fruiting tree seeds through their frugivory. They are also important predators of wood-boring beetle larvae.

Aye-ayes may inhabit cultivated areas and farmlands, including coconut and lychee plantations. As a result, they are sometimes considered crop pests. (Quinn and Wilson, 2004)

Aye-ayes are fascinating animals that are important members of native Malagasy ecosystems.

Daubentonia madagascariensis has been listed as an endangered species since the 1970s. In 1992 the IUCN estimated the total population to be between 1,000 and 10,000 individuals. The rapid loss of their natural habitat due to encroachment by humans is the main threat to this species. In addition, aye-ayes are hunted or killed on the spot by native Malagasy who see them as crop pests or bad omens. Currently, aye-ayes can be found in at least 16 protected areas across Madagascar. There is an effort to develop breeding colonies of captive aye-ayes. (Quinn and Wilson, 2004)

Daubentonia madagascariensis is the only extant member of the family Daubentoniidae. Fossils of a late Holocene species known as Daubentonia robusta have been recovered, which was about 30 percent larger than aye-ayes.

The common name "aye-aye" may be derived from the “hai-hai” vocalization they make while fleeing from their nests. (Quinn and Wilson, 2004)