Fig. 5. Difference in mean wing amplitude between pre- and post-manipulated birds. In manipulated birds, left or right wings were trimmed, by 0.25, 0.5 or 1.0 cm. Asterisks indicate where the resulting increase in wing beat frequency F_b was significantly higher than the pre-manipulated individuals. Values are means ± S.E.M. For N values, see Table 1.