An ecoethological study was undertaken on the activity rhythms, diet, ranging and social behavior of 3 aye-ayes. Preliminary information on reproduction and mother-infant relations are given. The study included research into the different habitat types in which the aye-aye was found within the Biosphere Reserve at Mananara-Nord. In addition, the impact of habitat degradation on aye-aye ecology was investigated. The aye-ayes spent the majority of time in locomotion; resting accounted for a surprisingly small amount of their activity cycles. Animals spent almost half of their time between 0 and 10 m above ground. Signs of aye-aye activity were never found in highly disturbed areas but were common in plantations, secondary littoral and primary forests.