Different timing of the migration of “eastern” Dunlin in the Baltic and Adriatic

We compare the timing of autumn migration of Dunlins showing plumage characters of easternmost C. a. alpina and westernmost C. a. centralis. We call the latter “eastern” Dunlins and distinguish them when they arrive in Europe by both the presence of adult-buff coverts and a complete set of newly grown primaries. Eastern Dunlins arrived on the Polish Baltic coast in the second ten days of August, about 20 days earlier than on the Adriatic. During late August and September, the proportion of eastern Dunlins in the Baltic was 19.9% of adults, while in the Adriatic the proportion was significantly lower at 6.9%. We suggest that eastern Dunlins, heading to the central and western Mediterranean, stop in the Black Sea to complete their primary moult, so delaying arrival on their wintering grounds. The proportion of eastern Dunlins in the Baltic is higher than in the Adriatic, probably because their main migration route leads them from Siberia through the Baltic to wintering grounds around the North Sea. Only a small proportion of them cross eastern European inland heading for the Black Sea and Mediterranean. Biometrics suggest differences between the wintering grounds of the sexes, with females outnumbering males along the East Atlantic flyway and vice versa in the Mediterranean.