Positional behaviour in captive aye-ayes (Daubentonia madagascariensis).

The aye-aye shows numerous special features in its postcranial skeleton, partly in association with its unusual feeding habits and partly in association with locomotor specialisation connected with the possession of claws. This study examined the positional behaviour of 3 captive adult aye-ayes in order to throw light on these morphological specialisations. Locomotion was dominated by quadrupedal walking and climbing. Given the relatively large body size of aye-ayes, an unexpectedly high frequency of head-first descent was observed. This may provide an explanation for two characteristics of aye-ayes: robusticity of the shoulder girdle and high compressive and bending strengths of the humerus. Agile leaping was also observed, contrasting with previous reports that this species is characterised by slow, cautious movement. Specific morphological features that are shared with slow-moving lorisids may be attributable to a combination of frequent head-first descent and postural suspension.