Adapted for foraging: The Aye-Aye

Daubentonia madagascariensis, commonly known as the Aye-Aye, is a rare lemur that is endemic to and only found on the island of Madagascar. They are a nocturnal species that spend their lives in the treetops, having adapted to various habitats including primary rainforest, deciduous forest, dry scrub areas, cultivated forest and mangrove swamps (IUCN, 2013). The IUCN Red List currently lists the Aye-Aye as Near Threatened, with a decreasing population size primarily due to declining area and quality of available habitat as well as ongoing persecution by locals due to the belief that it is a harbinger of evil.

Aye-Aye on a branch <http://www.arkive.org/aye-aye/daubentonia-madagascariensis/image-G130929.html>

The main thing that makes the Aye-Aye stand out from other lemurs, aside from its fuzzy cuteness (this is open to interpretation), is its technique for finding food. The Aye-Aye has an elongated middle finger, which is used for percussive foraging or tap-scanning (Dominy & Rasier, 2012).

Holes in tree from Aye-Aye feeding <http://www.arkive.org/aye-aye/daubentonia-madagascariensis/image-G6157.html>

Aye-Aye using thin elongated finger to find grubs in wood <http://www.arkive.org/aye-aye/daubentonia-madagascariensis/image-G113600.html>

As the Aye-Aye is searching for food it will use this middle finger to tap on the branches and trunks of trees, using changes in frequency to find insect hollows within the tree, as well as using these changing frequencies to detect the movement of the insect larvae that it feeds on. After locating insect larvae within a branch it then uses its teeth to create a hole in the branch, after which it will then again use its specially adapted middle finger. As well as being elongated, this finger is also highly mobile due to a specialized ball and socket joint, similar to those found in our own shoulders, allowing it to rotate around the hand enabling the Aye-Aye to effectively hook out insect larvae from deep within the hollows.

As an aside, here is a humorous summary of facts about the Aye-Aye

Zefrank1, 2013, 3rd May 2014 <https://www.youtube.com/watch?v=jHs5POy8-8Y>

References:

- Ramsier. M & Dominy. N., 2012, 'Receiver bias and the acoustic ecology of aye-ayes', Communicative & Integrative Biology, vol. 5, no. 6, pp. 1-4

- Myers, P, 2000. "Daubentoniidae", Animal Diversity Web, viewed 2nd May 2014 <http://animaldiversity.ummz.umich.edu/accounts/Daubentoniidae/>

- ARkive, 2013, viewed 3rd May 2014 <http://www.arkive.org/aye-aye/daubentonia-madagascariensis>

- Andrainarivo, C. et al, 2008. Daubentonia madagascariensis. In: IUCN 2013. IUCN Red List of Threatened Species. viewed 2nd May 2014 <http://www.iucnredlist.org/details/6302/0>.