In granivorous songbirds, feeding performance is a major driver in the evolution of beak morphology. This is illustrated by several classical works relating beak shape to feeding ecology (e.g., in Darwin's finches). However, beak shape alone fails to provide comprehensive explanations for functional trade-offs between specific aspects of feeding performance, in particular those involving beak movement to handle seeds. We lack quantitative data on how the cranial system generates controlled three-dimensional movement of the upper and lower beak during the processing of seeds. To achieve a better understanding of the mechanics of granivory, I will investigate the musculoskeletal mechanics of the cranium during grasping, positioning, and dehusking of seeds in three species of granivorous songbirds that vary in beak shape and bite strength. Both experimental and computational approaches will be used, including high speed imaging, biplanar x-ray videography, mechanical testing of muscle and ligament properties, and multi-body musculoskeletal modeling. This study will provide unprecedented insight into the kinematics and dynamics of the cranial system. My findings will help to bridge fundamental knowledge gaps on avian cranial function, and also provide the biomechanical basis for understanding the relations between beak movement performance and evolution in songbirds.