Supplementary material
Supplementary Table 1. List of the study species including information on subspecies examined, sample size, moult extent, Δ migration distance, mean latitude and body mass.
Supplementary Table 2. The effects of longitude (east or west) and year on the extent of moult: list of statistical models (GLM), statistics and Akaike Information Criterion, modified for small sample sizes (AICc) per species.
Supplementary Note 1. Supporting information for Figure 5.
Supplementary Figure 1. The difference in mean moult extent (number of moulted feathers) between Eastern and Western Palearctic birds for 21 passerine species. The boxplots display the minimum, 1st and 3rd quartiles, median and maximum of each tested region.