The numbers of adult females and first-winter long-tailed ducks Clangula hyemalis shot in eastern North America between 1972 and 1994 have fallen, though the kill of adult males shows no trend. Most of these ducks are likely to have originated in the Arctic Tundra climatic region of Canada. Although summer and autumn temperatures in that region have shown no trends since 1972, their annual variations can account for 19–53% of the variations in the breeding success of eastern-wintering long-tailed ducks, as reflected by the numbers of first-winter birds in the kill.