Fig. 16. Gait transition results obtained for dove 1 flying at 7 m s^-1 over several wingbeat cycles lasting 2 s. (A) The vertical (z direction) motions of the distal and proximal wing sections; (B) the mean vertical acceleration achieved during each complete wingbeat (not including acceleration to counteract gravity); (C) the mean distal wing circulation produced during the downstroke (squares and solid line) in relation to the mean proximal wing circulation produced during the subsequent upstroke (circles and dashed line). The lines plotted in B and C represent cubic spline fits to the data points. The shaded regions indicate wingbeats in which the bird employs a vortex-ring gait.