Fig. 5

Shifted headings of birds when the wind direction is considered as 0° at CMDT before (a) and after sunset (b) and at YLE before (c) and after sunset (d). Each filled dot shows the direction of an individual bird. The average direction (α, arrow at the center of the circle), sample size (n), mean vector length (r, length of the arrow), p value of the Rayleigh test, and 95% confidence interval (lines beside the arrow) are presented. For confidence intervals, solid lines indicate a p value < 0.05, while dashed lines indicate a p value > 0.05. Note that wind direction (black bold arrow outside the circle) is the direction from which wind is blowing. In tests at YLE after sunset (d), the data were excluded from the analysis for four birds tested on the same day in the absence of wind