Sex-related differences in autumn migration timing of adult common sandpipers Actitis hypoleucos (Linnaeus, 1758) (Charadriiformes: Scolopacidae)

In the common sandpiper both sexes do not participate equally in brood rearing. The attendance of females progressively declines and by the third week after hatching, most of them leave their broods. To check if this unequal parental care results in different migration phenology of males and females, adult common sandpipers were caught at four ringing sites in Poland during their autumn migration and were sexed using a discriminant equation. The median date of female migration was 6 days earlier than that of males. In the first days of July, males comprised only 22% of common sandpipers caught, while later their percent share increased gradually and in August reached up to 80% of captured birds. However, birds of both sexes were present among migrants during the whole migration period and migration period of both sexes overlapped to a great extent. Most probably birds migrating through the study area came from a vast breeding area, where the period of egg laying differs between its northernmost and southernmost parts by at least 1 month