Fig. 4. Deflection of lesser upper- and underwing coverts during a mid-flight gust response over a sea cliff. (A–D) Covert feather deployment and (E–H) covert feather retraction. Interval between images: 20 ms between rows; 320 ms between columns. The coverts remain in approximately the same deflected position between frames D and E. An animation of the complete sequence is provided in supplementary material Movie 4.