Fig. 5. Velocity fields in the wake of an adult chukar Alectoris chukar during ascending flight at 80°, revealed using DPIV. Backgrounds illustrate the bird (A) and vorticity, (B). Transparent red loops in A represent an assumed 3D shape of vortex ring as inferred from concentrations of about and . Effects of two downstrokes are shown, with starting and ending vortex cores evident as concentrations of ^– and ⁺, respectively, in B.