Post-fledging broods of migratory Harlequin Ducks accompany females to wintering areas

We describe evidence that Harlequin Duck (Histrionicus histrionicus) broods accompany their mothers from breeding streams to coastal molting or winter ing areas. Observations indicated that all surviving female-offspring group s left breeding areas together. We later sighted some family members at the coast near each other, suggesting that they had arrived together, then sep arated. We observed family groups at wintering areas in August and Septembe r Family groups tended to separate quickly, although some family members ma intained contact for over five months. To our knowledge the evidence we pro vide is the first suggesting that female migratory ducks bring their offspr ing to wintering areas, a pattern similar to geese and swans. This may be f acilitated by an unusual strategy of wing molt, in which Harlequin Ducks mo lt after migrating to wintering areas. Due to winter pairing and strong phi lopatry in Harlequin Ducks, migration of families may contribute to genetic differentiation among populations.