Fig. 5. Wingbeat kinematics during free hovering and load-lifting in Peruvian hummingbirds. (A,B) Raw species data, (C,D) phylogenetically corrected independent contrast data. Solid lines, free flight; broken lines, load-lifting. Wingbeat frequency decreased with increasing body mass during both load-lifting and free hovering flight. Stroke amplitude increased with increasing elevation during free flight, but not with elevation during load-lifting, because all hummingbirds reached a maximum stroke amplitude of approximately 180° at the point of maximum lifting. See text for regression equations.