Energetic costs of feeding behaviors in the aye‐aye, Daubentonia madagascariensis (918.14)

The aye‐aye is a 2.5‐3kg lemur that has a specialized feeding apparatus featuring rodent‐like incisors which they use during extractive foraging on wood‐boring larvae and seeds. To evaluate these behaviors, we measured the energetic costs of feeding on whole seeds and wood gnawing in aye‐ayes (n=4) using open‐flow respirometry. Rates of oxygen consumption were measured during stable periods of rest and feeding for each experiment. The net feeding costs reported are the cost of feeding minus the energy expended during rest in Watts. The mean net feeding rate was 14.7W (SD 3.7) during wood gnawing and 5.6W (SD 2.5) during seed eating. Our results show that wood gnawing was significantly more costly (Wilcoxon, p<0.0001) than seed predation for aye‐ayes. These differences are partially caused by variation between material properties of food objects and wood, but may also be mediated by differences in feeding behavior; wood gnawing aye‐ayes likely recruit postcranial muscles to maintain tooth contact with a large, immobile surface while closing their jaws. While these data suggest that extracting larvae is a costly behavior, insect larvae are rich in protein and fat and are less seasonal than the seeds consumed by wild aye‐ayes. Specialization of the incisor teeth to maximize bite pressure and resist wear are likely adaptations to high cost, high reward foraging behaviors in the aye‐aye.