Short- to medium-distance migrant. Birds that breed in the northwest of North America migrate to the northwest Pacific Coast. Breeders in eastern Canada and Greenland winter primarily along the coast of Atlantic Canada and New England. Many males form small, loose flocks and leave their breeding grounds by late June. Females begin to return to the coast with young birds from July into September. Males stop over in molting sites, where large numbers congregate during this brief period of flightlessness. They often arrive on their wintering grounds in late October. Wintering birds begin leaving for their breeding grounds in late March.