Figure 2

Examples of high-speed videography of the budgerigars flights while traversing the gap. Panel (A) shows a bird `projectiling through the gap with its wings almost completely tucked back. Bird shown is Drongo (wingspan 31cm), the gap width in the example is 28cm. Panel (B) shows a budgerigar traversing the gap with its wings held above its body for a prolonged time. Bird shown is One (wingspan 31cm), the gap width is 28cm. The individual frames display the birds posture at the end of each downstroke, before and after the gap and additionally the body-posture during traversal (full videos can be found in the Additional files 1 and 2).