Daubentonia madagascariensis

Geographic Range

Daubentonia madagascariensis , commonly known as the aye-aye, is endemic to Madagascar. Aye-ayes can be found widely distributed across the island.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

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.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• rainforest rainforest

Physical Description

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.

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

During each mating cycle females typically mate with more than one male, representing a multi-male, multi-female mating system.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Aye-ayes have an extended mating season. Observations in the wild showed a five month period from October to February when individuals were mating, or there were visible signs of females in estrus. Female estrous cycles range from 21 to 65 days and are characterized by changes in the vulva, which is usually small and gray, and becomes large and red during these cycles.

There is a gestation period of 152 to 172 days, and infants are typically born between February and September. There is a 2 to 3 year interval between births. This long interbirth interval may be due to the relatively slow development of young and high levels of parental investment.

Aye-ayes have an average neonatal weight of 90 to 140g and will grow to be roughly 2615 g for males and 2570 g for females. Infants have a coat that is similar in color to adults, but they are distinguished in appearance by their green eyes and floppy ears. Infants also have a deciduous dental formula of: I:1-2/1-2, C1/1, PM:2/2. This deciduous dentition is shed at 20 weeks.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Aye-ayes have a relatively slow rate of development, compared to other Strepsirrhini . Observations of this species in the first year of development showed that young first left the nest at 8 weeks. They began feeding on solid food regularly at 20 weeks, the same time that the deciduous dentition is lost, and were still food begging and making attempts to suckle at one year old. This extended period of dependence is probably related to their highly specialized feeding behaviors. Young aye-ayes typically achieve adult proficiency in locomotion by 9 months and reach sexual maturity by 2.5 years.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female
• extended period of juvenile learning

Lifespan/Longevity

A captive female lived to an age of 23.3 years.

Behavior

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.

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.

• Key Behaviors
• arboreal arboreal
• scansorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary

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.

Communication and Perception

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.

• Communication Channels
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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.

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.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
• herbivore herbivore
  • frugivore frugivore

• Animal Foods
• insects

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit
• nectar
• sap or other plant fluids

Predation

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.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

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

Economic Importance for Humans: Positive

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

Economic Importance for Humans: Negative

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

• Negative Impacts
• crop pest

Conservation Status

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.

Other Comments

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.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Elizabeth Boucher (author), Yale University, Eric Sargis (editor, instructor), Yale University.

References

Ancrenaz, M., I. Lackamancrenaz, N. Mundy. 1994. Field Observations of Aye-Ayes. Folia Primatologica , vol. 62 issue 1-3: 22-36.

AnkelSimons, F. 1996. Deciduous Dentition of the Aye-Aye. American Journal of Primatology , vol. 39 issue 2: 87-97.

Dierenfeld, E., C. Ashbourne, A. Feistner. 1994. Dietary-intake, Food Composition and Nutrient Intake in Wild and Captive Aye-Ayes. Folia Primatologica , vol. 62 issue 1-3: 115-124.

Erickson, C., S. Nowiki, L. Dollar, N. Goehring. 1998. Precursive Foraging: Stimuli for Prey Location by Aye-Ayes. International Journal of Primatology , vol. 19 issue 1: 111-122.

Erickson, C. 1995. Feeding Sites for Extractive Foragaing by the Aye-Aye. American Journal of Primatology , vol. 35 issue 3: 235-240.

Feistner, A., C. Ashbourne. 1994. Infant Development in a Captive Bred Aye-Aye. Folia Primatologica , vol. 62 issue 1-3: 74-92.

Feistner, A., E. Sterling, Dodo. 1995. Body Mass and Sexual Dimoorphism in the Aye-Aye. Journal of the Wildlife Preservation Trusts , vol. 31: 73-76.

Kaufman, J., E. Ahrens, D. Laidlaw. 2005. Anatomical Analysis of an Aye-Aye Brain Combining History, Structural Magnetic Resonance Imanging and Diffusion-Tensor Imaging. Anatomical Record , vol. 287A issue 1: 1026-1037.

Krauker, J., P. Lemlin, D. Schmidt. 2002. Hand and Body Position During Locomotor Behavior in the Aye-Aye. American Journal of Primatology , vol. 57 issue 3: 105-118.

Mittermeier, R., W. Konstant, F. Hawkins, E. Louis, O. Langrand, J. Ratsimbazafy, R. Rasoloarison, J. Ganzhorn, S. Rajaobelina, I. Tattersall, D. Meyers. 2006. Lemurs of Madagascar . Colombia: Conservation International, Tropical Field Guide Series.

Quinn, A., D. Wilson. 2004. Daubentonia madagascariensis. Mammalian Species , vol. 710: 1-6.

Soligo, C. 2005. Anatomy of the Hand and Arm in Daubentonia Madagascariensis. Folia Primatologica , vol. 76 issue 5: 262-300.

de Magalhães, J. 2007. "Daubentonia madagascariensis" (On-line). AnAge: The Animal Ageing Resource. Accessed December 18, 2007 at ttp://www.genomics.senescence.info/species/entry.php?species=Daubentonia_madagascariensis .