Nocturnal Activity of a Captive Aye-aye (Daubentonia madagascariensis)

Abstract

This report aims to clarify the nocturnal activity of the aye-aye (Daubentonia madagascariensis) under captive conditions to compare it with that under natural conditions. The aye-aye was nocuturnal and showed activity at any time at night. However, from 02:00 hrs until just prior to dawn, it often rested. It frequently returned to the nest throughout this period to take long rests of more than half an hour. The aye-aye's activities were classified into four categories: feeding, moving, resting and other activities. The average proportions of these activities were 14.8%, 25.3%, 56.7% and 3.2%, respectively. The relative proportions of the activities showed seasonal changes. Rises in atmospheric temperature were highly correlated with increases in the proportion of moving (r=0.908). Generally speaking, the proportion of feeding was high in the early evening and gradually fell as night progressed. The four activities were sub-divided into several component acts. In terms of component acts, hanging was positively correlated with a rise in temperature (r=0.889), while sitting was negatively correlated (r=-0.862), suggesting that the activity of the aye-aye is generally enhanced with rises in atmospheric temperature. The aye-aye engaged in tapping and gnawing throughout the period. These acts consisted of along duration of gnawing at definite places on the window or the steel frame of the door. Since the proportion of feeding activity was virtually undetermined under natural conditions because of intermittent observations and fragmented data, we assumed that it would be similar to that seen in the captive condition. On average, the aye-aye engaged in feeding for 89 minutes during a night, and consumed 48.5 ramy fruits or ingested 212 kcal. The energy intake from this quantity of ramy fruits would be sufficient, considering the basal metabolic rate of prosimians. These analyses support a hard-nut adaptation hypothesis suggesting that ramy fruit is an important staple food of the aye-aye. During the period of study, the aye-aye was presented with 12 diet items such as coconuts, ramy nuts, bread, etc. The weight of food consumed during meals was measured over 16 nights to calculate the energy intake of the aye-aye, which was found on average 306.1 kcal per meal. The response of the aye-aye to light was markedly different from other nocturnal prosimians. The aye-aye was not apparently disturbed when exposed to intense light.