Figure 7

Histogram and cumulative distribution function of all flights where birds did not close their wings. The blue bars depict a histogram of the frequency of occurrence of the last wing extension prior to passage through the gap, along a time scale (lower abscissa) and a distance scale (upper abscissa), assuming an average flight speed of 4m/s, as explained in the text. The blue curve shows the cumulative distribution function. The dashed horizontal lines show cumulative probability levels of 20% and 50%. The vertical arrow on the time scale represents the average duration of one uninterrupted wing beat cycle (60ms).