The aye-aye is the largest nocturnal primate in the world and the only living member of the family Daubentoniidae, a lineage that diverged early in lemur evolution and has no close living relatives [NEPC 2023][Sterling 1994]. Endemic to Madagascar, it is among the most morphologically distinctive of all primates, combining ever-growing incisors, large mobile ears, and an extraordinarily elongated middle finger used to locate and extract wood-boring insect larvae [ADW 2020]. For much of its history the species was thought to be exceptionally rare, in part because it is solitary, active only at night, and difficult to survey; recent whole-genome work now indicates the global population is small and has been declining over recent decades [Terbot et al. 2025].
Because it is so unlike any other animal, the aye-aye has long occupied a singular place in Malagasy culture and in the scientific record. It is also one of Madagascar's most imperiled primates, facing pressures that are both ecological and cultural [IUCN 2020].
Biology and Identification
The aye-aye weighs roughly 2.57–2.62 kg and measures about 360–440 mm in head-and-body length, with a long, bushy tail that exceeds the body in length [ADW 2020]. Its dentition is unusual among primates: the incisors are large and continuously growing, separated from the cheek teeth by a pronounced gap (diastema), a convergence on the rodent condition [ADW 2020]. The most diagnostic feature is the slender, highly mobile third digit of each hand.
The aye-aye uses this finger for percussive foraging: it taps rapidly on wood and listens for the resonance of hollow cavities, then gnaws an opening and inserts the thin digit to extract beetle larvae [Sterling 1994][ADW 2020]. This tap-foraging strategy, combined with sensitive ears, lets it exploit a food source that few other animals can reach [Sterling 1994]. Its diet also includes seeds, fruits, nuts, nectar, and plant exudates [ADW 2020]. The species is nocturnal and largely solitary, sleeping by day in spherical nests built in the canopy [ADW 2020][NEPC 2023].
Habitat and Range
The aye-aye is endemic to Madagascar and has one of the broadest distributions of any lemur, recorded across much of the island in eastern rainforest, western dry deciduous forest, and some degraded and secondary habitats [IUCN 2020]. This wide range can give a misleading impression of abundance: the species occurs at consistently low densities, and its nocturnal, elusive habits make reliable population counts difficult [IUCN 2020][SDZWA 2021].
Genomic analysis indicates the species is structured into at least two distinct populations, broadly a northern group and a non-northern group, rather than a single panmictic population [Terbot et al. 2025]. In keeping with sensitive-species protocols, NRWL does not publish precise locality, nest, or den information; range is described here only at the level of island, biome, and broad region.
Conservation Status
The aye-aye is assessed as Endangered on the IUCN Red List, in the assessment published in 2020 [IUCN 2020]. The listing is based on a suspected population decline of at least 50% over a period of approximately 36 years (three generations), driven primarily by continuing decline in the area, extent, and quality of its forest habitat, together with unsustainable levels of hunting and killing [IUCN 2020].
Recent whole-genome work is consistent with this trajectory. Researchers inferred two reductions in population size: an ancient bottleneck roughly 5,500 years before present, coinciding with the estimated arrival of humans on Madagascar, and a second, more recent reduction over the past few decades linked to habitat loss; their analyses place the total effective population size below about 2,000 individuals [Terbot et al. 2025]. The IUCN population trend is recorded as decreasing [IUCN 2020].
Threats
Habitat loss is the leading threat across the aye-aye's range. Forest is cleared for agriculture, charcoal, and timber, and certain trees that supply important foods are felled preferentially for construction and other uses [IUCN 2020][SDZWA 2021]. Because the species depends on mature wood for both foraging and nesting, habitat degradation reduces resources even where some forest cover remains [SDZWA 2021].
The aye-aye also faces direct persecution. It is hunted for food in some areas and killed as a perceived crop pest, and in parts of Madagascar a cultural belief treats the animal as an omen of misfortune, leading people to kill individuals on sight [IUCN 2020][NEPC 2023]. This combination of habitat loss and targeted killing is unusual in its intensity and makes the species' outlook difficult to improve through habitat protection alone [IUCN 2020].
What Is Being Done
The aye-aye is protected under Malagasy law and is listed on CITES Appendix I, which restricts international commercial trade [IUCN 2020][CITES 2020]. It occurs in a number of protected areas across the island, and dedicated lemur conservation programs work on forest protection, community engagement, and research into the species' ecology and genetics [IUCN 2020][SDZWA 2021]. Insurance populations are maintained in a small number of accredited institutions, supported by studbook coordination, which helps preserve genetic diversity and supports research into the species' specialized biology [SDZWA 2021]. Recent genomic studies provide a clearer baseline of population structure and size, information that can inform where conservation effort is most needed [Terbot et al. 2025].
How You Can Help
Members of the public can support the aye-aye by learning about Madagascar's forests and sharing accurate information, since cultural misunderstanding contributes directly to the killing of individuals [NEPC 2023]. Supporting established conservation organizations and accredited zoological institutions that fund habitat protection and field research in Madagascar contributes to long-term efforts [SDZWA 2021]. Choosing responsibly sourced products that reduce pressure on tropical forests, and supporting credible reforestation and community-conservation initiatives, also helps protect the habitats the species depends on [IUCN 2020].
References
[IUCN 2020] Louis, E.E., Sefczek, T.M., Randimbiharinirina, D.R., Raharivololona, B., Rakotondrazandry, J.N., Manjary, D., Aylward, M. & Ravelomandrato, F. (2020). Daubentonia madagascariensis (Aye-aye). The IUCN Red List of Threatened Species 2020: e.T6302A115560793. https://www.iucnredlist.org/species/6302/16114609
[Terbot et al. 2025] Terbot, J.W. II, Soni, V., Versoza, C.J., Pfeifer, S.P. & Jensen, J.D. (2025). Inferring the Demographic History of Aye-Ayes (Daubentonia madagascariensis) from High-Quality, Whole-Genome, Population-Level Data. Genome Biology and Evolution, 17(1): evae281. https://doi.org/10.1093/gbe/evae281
[ADW 2020] Animal Diversity Web. Daubentonia madagascariensis (aye-aye). University of Michigan Museum of Zoology. https://animaldiversity.org/accounts/Daubentonia_madagascariensis/
[Sterling 1994] Sterling, E.J. (1994). Aye-ayes: Specialists on structurally defended resources. Folia Primatologica, 62(1-3): 142–154. https://doi.org/10.1159/000156771
[SDZWA 2021] San Diego Zoo Wildlife Alliance. Aye-aye (Daubentonia madagascariensis) Fact Sheet: Population & Conservation Status. https://ielc.libguides.com/sdzg/factsheets/ayeaye/population
[CITES 2020] CITES. Appendices I, II and III — Daubentonia madagascariensis. Convention on International Trade in Endangered Species of Wild Fauna and Flora. https://cites.org/eng/app/appendices.php
[NEPC 2023] New England Primate Conservancy. Aye-Aye (Daubentonia madagascariensis). https://neprimateconservancy.org/aye-aye/