Meeting Abstract
Gusts and turbulence present serious challenges to flying birds. In windy conditions, gust magnitudes can be similar to avian flight speeds, with the potential to cause rapid attitude and flight path deviations. Birds appear to counter this by changes to the pose and shape of their wings and tail, which indicates either a strong gust mitigation strategy and/or rapid recovery movements. To understand the impact of gusts on birds in steady gliding flight, we flew two individuals, a barn owl (Tyto alba) and a goshawk (Accipiter gentilis), along a straight indoor corridor through an acute updraft. Each flight was recorded using an array of high-speed cameras positioned above and below the flight path. We used photogrammetric image-matching techniques to reconstruct 3D point-clouds of each bird’s dynamic surface geometry throughout the updraft event. Both birds altered their wing morphology and maintained a level flight trajectory with minor changes in attitude; by comparison, a stiff-winged model glider of similar scale experienced large vertical and pitch deviations. We investigate the initial rejection of the perturbation by the birds’ wings for multiple gust strengths, including the relative contributions of rigid-body motion and morphing shape-change. For both individuals, wing deflection appeared to result in body stabilization through aeroelastic mechanisms.
