Resource preference of an adult female aye-aye (Daubentonia madagascariensis) in Madagascar's Ihofa Forest.

Abstract

Aye-ayes possess an unusual suite of morphological characteristics that are used to locate and extract xylophagous invertebrates. A growing body of evidence supports the long-held claim that xylophagous invertebrates comprise a significant portion of aye-aye diets; however, several aye-aye features are also used to harvest endosperm from seeds of Canarium spp., another important aye-aye resource. Using continuous focal animal sampling, we collected feeding data on a female aye-aye in Madagascar's Ihofa Forest from January 2016 to December 2017 to better elucidate resource preference. We used aye-aye feeding traces in woody substrates as a proxy for xylophagous invertebrate presence to estimate xylophagous invertebrate abundance along 20 transects (10 m × 100 m). During observational follows, we also counted each trace made during feeding. Using the same transects, we also estimated Canarium seed abundance based on fruit in the canopy and fruit on the ground. There were more aye-aye feeding traces in woody substrates for xylophagous invertebrates (3206) than for Canarium seeds (2153). A Wilcoxon signed-rank test found no significant difference in the number of xylophagous invertebrates and Canarium seeds consumed during this study ( p = 0.317); however, a two-item preference index indicated that xylophagous invertebrates were the preferred resource monthly and annually. Our results indicated that the aye-aye in this study preferentially consumed xylophagous invertebrates. This provides further evidence that the aye-aye's highly derived morphology is specifically adapted for extracting insect larvae from structurally defended substrates. The use of some of these morphological autapomorphies for Canarium seed feeding may be an example of an exaptation.