Fig. 6. Pectoralis mass specific aerodynamic power estimated from the wing kinematics at mid-downstroke, stroke duration and wrist arc during downstroke, shown as the inter-individual mean ± s.d. Across all birds and wingbeats, power averaged 238.24±80.85 W kg^–1 (N=58). Note that data for wingbeat –3 were not available because a stroke duration, measured from mid-upstroke to mid-upstroke, was not available from 4 of the 6 birds.