Fig. 3

During 2016–2019 fall migration in Norfolk County, Ontario, adults averaged a greater wind advantage during their flights across Lake Erie than juveniles (A). The advantage gained from tailwind was closely linked to flight speed, and adults were more likely to initiate migration on nights with favorable wind conditions (B). The tailwind metric ranges between about 10 and −10 and indicates the relative advantage the wind gives a bird during flight. Wind speed and direction are used to calculate the tailwind metric, with a direct and strong tailwind producing higher positive scores and a direct and strong headwind producing lower negative scores