Fig. 1

Maps showing the migration routes and stopover sites of A. a. pekinensis. N = 25 (for details see Additional file 7: Fig. S2). In A (autumn) and B (spring): the gray hatching shows the breeding distribution of pekinensis [15, 44], the dotted lines indicate the lack of data in the two weeks before/after the equinoxes, and the base map shows the global annual precipitation distribution. The circles in C (autumn) and D (spring) represent the stopover sites. Different colour symbols represent different individuals. The pentagram represents the pekinensis breeding site and fieldwork location in Beijing.