Figure 4.

Average kinematics for three wing beats from four hummingbirds: (a) ϕ, humeral long-axis orientation, (b) long-axis rotation rate, (c) wing-tip speed and (d) γ, the angle between the humerus and the leading edge of the wing (figure 1). Downstroke is indicated by the vertical shaded regions, the blue shaded margins of the curves show ± 1 s.d. n = 4 birds. Wing beat frequency was 43 ± 5 Hz.