Fig 4. Displacement of the crest in response to air vortices.

(A) Time series showing the change in flag position after a peacock crest (Crest 09) was impacted by a moving vortex of air. When peafowl crests were impacted by such air ring vortices, they deflected measurably, oscillating at their resonant frequency with an amplitude that decayed to a few percent of the initial value over the period of the peacock’s wing-shaking display. (B) Mean resonant frequencies (f_r) and mean vortex response frequencies (± 95% CI) for three crests in the vortex experiment.