Figure 2.

Variation in body and wingbeat kinematics, and values for metabolic rates and aerodynamic parameters of Anna's hummingbirds flying in the wake of von Kármán vortex streets generated by three cylinders of different diameters (2 cm, small; 4 cm, medium; 9 cm, large), and in an undisturbed control airflow, at airspeeds of 3 m s⁻¹ (black), 6 m s⁻¹ (blue) and 9 m s⁻¹ (red): (a) average standard deviation of body yaw γ_b (circles) and tail yaw γ_t (squares); (b) average standard deviation of body pitch β_b (circles) and tail pitch β_t (squares); (c) average standard deviation of body roll ψ; (d) average standard deviation of wingbeat frequency n (left circles: left wing, right circles: right wing); (e) average standard deviation of wingbeat amplitude for each wing Φ (left circles: left wing, right circles: right wing); (f) average values for mass-specific rates of oxygen uptake. For details, see text and table 1. Error bars indicate 1 s.d.