Fig. 4. The difference in mean wing beat frequency (F_b) between pre- and post-manipulated birds (beats s^–1). The largest increase in F_b from pre-manipulated levels occurs between the birds that had 1.0 cmremoved from one wing. ^*Increase in F_b was significantly higher than in the pre-manipulated individuals. Values are means ± S.E.M. For N values, see Table 1.