Fig. 6. Comparison of the effective wingbeat frequency for radar-tracked hirundines with wind tunnel observations. (A) Barn swallows; (B) house martins. Medians (horizontal bars), 25-75% ranges (boxes) and range (whiskers) are given. Shaded boxes represent wind tunnel data, open boxes represent field data. Flight angles of radar-tracked hirundines were restricted to climbing (5±3°), horizontal flight (0±1.5°), descent at -5±1.5° and descent at -10±3° (means ± S.D.). Only one measurement per bird was included per flight angle. Numbers of individuals are given on the graph.