Movements of the skeleton of a starling in flight visualized with high speed X-ray film techniques provide 3-D insight on internal wing beat dynamics. The timing of electrical activities (EMGs) of the larger flight muscles in flight is presented in relation to the different phases of the wing beat cycle. The pectoralis is responsible for the downstroke of the wing and for forward rotation (pronation) of the humerus. Forces are measured directly at the insertion on the deltopectoral crest, allowing mechanical power estimates in flight at different speeds. The supracoracoideus muscle is not only involved in powering the upstroke, but also plays an important role in the backward rotation (supination) of the wings. The timing of EMG activity in tail muscles during walking and flight reveals complex kinematic patterns. The relationship with force production remains unclear. Measurements of pressure changes in the anterior air sacs reveal a complex relationship with respiration.
Keywords: dynamics, electromyogram, wing muscles, wing beat cycles, pectoralis, supracoracoideus, pronation, supination, tail muscles, respiration