Patterns and laterality of hand use in free-ranging aye-ayes (Daubentonia madagascariensis) and a comparison with captive studies

We observed hand use in free-ranging aye-ayes (Daubentonia madagascariensis) on an island in the Mananara River, eastern Madagascar. The results were compared with those of two conflicting studies on hand laterality in captive aye-ayes. We argue that patterns of hand preference in wild aye-ayes are comparable to those of captive animals and that discrepancies between studies are—at least partly—caused by different ways of collecting and processing data. Aye-ayes fit Level 2 of the categories of hand laterality described by McGrew and Marchant (Yearb Phys Anthropol 40:201–232, 1997), with some individuals showing significant hand preference, but with the proportion of right- to left-preferent animals being very close to 1:1. We observed hand preference to be consistent for two of the most frequent behaviors, tapping and probing with fingers. Reaching and holding objects in hands is rare in aye-ayes, and the patterns of hand use in aye-ayes are therefore not directly comparable with those of other prosimians in which laterality has been studied. We detected no effect of sex on hand preference and were unable to determine whether there is an effect of age. The posture adopted by the animals did not influence hand preference.