Kinetics and Energetics of Feeding Behaviors in Daubentonia madagascariensis
The primary aim of this thesis was to quantify the ways Daubentonia uses its specialized feeding apparatus during naturalistic feeding behaviors. This can be divided into two main objectives. The first objective was to better understand how these extreme specializations function in the extractive foraging niche of Daubentonia. The second objective was to use Daubentonia to test for previously unmeasured behavioral modifications of bite forces using the post-cranial musculature. To do this I carried out two experiments measuring the kinetics of wood gnawing and the energetics of feeding behaviors. The main results of these experiments were: 1) Daubentonia does not generate relatively high magnitude bite forces during wood gnawing compared to their maximal voluntary bite force, but wood gnawing is extremely energetically costly compared to other feeding behaviors. 2) Daubentonia recruits post-cranial musculature during wood gnawing, most frequently generating a neck-extending moment that increased the magnitude of bite forces on the mandibular incisor. 3) The energetic costs of feeding were positively correlated with the toughness of foods. 4) The rate of energetic costs (J/s) incurred during the processing and mastication of whole nuts is not significantly greater than the rate of costs to masticate small pieces of nut kernels, but the increased handling time increases the net cost per gram of food consumed (J/g). Taken together, these experiments inform the primary aim of this study. Daubentonia appears to possess a highly specialized toolkit for fracturing stress-limited foods. Their large jaw adducting musculature, rodent-like incisors, and relatively short mandible allow them to produce large bite pressures to rapidly fracture the shells of nuts. Furthermore, it was demonstrated that Daubentonia transfers some forces from the post-cranial musculature to its incisors during wood gnawing and that the energetic costs of this wood gnawing behavior approach what is expected for sustained locomotor costs. This work illuminates a new avenue for investigation in jaw biomechanics: the assistance and modification of bite forces using the post-cranial musculature.
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