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Declines of Greater and Lesser Scaup Populations: Issues, Hypotheses, and Research Directions


The consensus of workshop participants was that scaup populations have declined. BGS numbers are down and age ratio in harvest for lesser scaup has declined, indicative of poor recruitment. Analyses of BGS data by MacCluskie et al. indicate that the scaup decline occurred primarily in Canada's western boreal forest, east of the continental divide. This is the primary breeding range for lesser scaup. Whether greater scaup breeding there also are declining is unknown.

Various factors may be contributing to these declines, and extensive research and analyses are needed to identify them. Contaminants, lower female survival, and reduced recruitment due to changes in breeding-ground habitat or food resources are believed to be the primary factors contributing to the scaup decline. These factors are not mutually exclusive and likely interact across seasons. The range of issues and of geography involved makes addressing these hypotheses complex.

Several themes were repeated in discussions and recommendations. These highlight research and information needed to address the hypotheses examined here and in Afton and Anderson (in review).

Two actions would help guide future efforts and reduce redundancy: (1) a website or periodic newsletter, to keep participants and others interested in scaup informed about current research plans, activities, and opportunities for collaboration, and (2) a designated coordinator for some studies, particularly examination of existing survey and harvest data and banding studies. Work by Allen et al. (1999) and Afton and Anderson (in review) provide a baseline for additional analyses.

Several participants suggested that a conservation plan, as done for seaducks, and an on-going working group would be valuable to provide information on scaup issues to concerned individuals and groups. A workshop focusing on scaup should be conducted at the Second International Duck Symposium at Saskatoon, Saskatchewan, in the fall of 2000.

Effective conservation of North American waterfowl requires cooperation and communication among agencies and organizations in the U.S., Canada, and Mexico. This workshop is the first step in focusing research directions and stimulating communication and partnerships among diverse groups concerned with scaup conservation and management. All of the recommendations presented here will require funding, commitments of personnel time and other resources, and partnerships and cooperative studies. We encourage all involved with scaup to keep others informed of their activities, and to seek opportunities for collaboration and interactions. We challenge the U.S Fish and Wildlife Service, U.S. Geological Survey, Canadian Wildlife Service, Flyway Councils and Technical Committees, and private conservation organizations to commit personnel and funding necessary to begin answering research and information needs identified at this Workshop. These steps should begin immediately to address possible causes of scaup population declines. With scaup showing a long-term decline of ~150,000 birds per year, the need for immediate action is clear.

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