Figure 3

Mean probability of wing closure (A) and normalised mean duration of the up-stroke during passage (B) as a function of the difference between the gap width and the birds wingspan, averaged over all 7 birds and including SEM. The percentage probability of wing closure for each bird was computed as 100* (No. of observed wing closures/10), from the 10 flights that were analysed for each bird, for each condition. The grey area represents the conditions in which the gap was wider than the birds wingspan.