Figure 6

Wing beat frequency and dynamic body acceleration were correlated for both (a) murres (N = 10) and (b) kittiwakes (N = 10). Wing beat frequency increased with wind speed in the direction of travel for both (c) murres (N = 10) and (d) kittiwakes (N = 10). For murres, inbound and outbound wing beat frequency differed significantly, and so we show both groups. In (c) and (d), dynamic acceleration is calculated based on the regressions in (a) and (b) and airspeed is calculated based on regressions in Figure 4.