Figure 3 Comparisons of (a) female and (b) male bill and wing lengths of dunlins sampled in Jiangsu in the autumn migration in 2015 (purple triangles) and 2016 (green circles). The mean ± standard deviation values for each year are shown at the top and side of each graph. Significances differences between years are indicated by*P< 0.05, according to either t -test or Mann–Whitney U-test.
For males, bill and total head lengths were significantly different between Alaskan and Beringian lineages (bill length, t = 2.172, df = 54, two-tailed P = 0.034; total head length, t = 2.769,df = 85, two-tailed P = 0.007) (Fig. 4a). Bill and total head lengths were shorter in the Alaskan lineage than in the Beringian lineage. By contrast, wing length was longer in the Alaskan lineage than in the Beringian lineage. For females, bill and total head lengths were both longer in the Alaskan lineage than in the Beringian lineage.