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Given these trends, we believe that research and monitoring efforts should be concentrated in the boreal forest of the Northwest Territories, northern Alberta, and northeastern British Columbia (hereafter called the Western Canadian Boreal Forest, WCBF). Further delineation of where the declines are occurring is a critical first step to addressing 2 main hypotheses about factors contributing to the decline. First, are declines in breeding populations related to habitat changes in the WCBF? This question could be addressed through retrospective analyses of population data with landscape, climate, and other habitat-related data; recommended research directions are outlined in the following section. Second, are declining populations affiliated with distinct wintering or migration areas? If populations in certain wintering or migration areas are exposed to greater contamination or sport harvest, reduced productivity or survival of that segment of the population may contribute to a long-term decline on breeding areas. Thus, we must first complete a detailed examination of existing breeding population data to determine more precisely where declines have occurred before addressing the main questions.

Another important question is whether populations of both or only 1 species are declining. Tundra strata (8-11, 13) are composed primarily of greater scaup, but their range overlaps with lesser scaup in boreal forest; only lesser scaup breed in prairie parkland. The larger component of lesser scaup in the combined population suggests that lesser scaup are a major component of the decline, but greater scaup in nontundra areas also may be declining. However, this question cannot be resolved without more information on the species composition in various breeding areas.