Figure 4.

Maximum speed attained by Anna's hummingbirds flying in a wind tunnel under five experimental treatments. Each line represents one hummingbird. The dashed lines represent birds that could match the tunnel's top speed. (a) The hummingbirds exhibited significantly lower maximum speeds in the long-tail treatment than they did when unmanipulated (control 1), or with a sham manipulation (control 2; repeated-measures ANOVA, p<0.0001, n=11 birds). (b) Maximum speed showed no change in the no-rectrix treatment, relative to the control values (n=10 birds, repeated-measures ANOVA, p=0.7). (c) The no-tail treatment exhibited a significant decrease in maximum speed relative to the controls (n=15 birds, repeated-measures ANOVA, p=0.02). The control values have been averaged in (b,c) because both controls were measured prior to these experimental manipulations.