Declining Scaup Populations:
Issues, Hypotheses, and Research Needs
Jeffrey S. Lawrence6, J. Bruce Pollard7, and James K. Ringelman8
Abstract: The population estimate for greater (Aythya marila) and lesser (Aythya affinis) scaup (combined) has declined dramatically since the early 1980s to record lows in 1998. The 1998 estimate of 3.47 million scaup is far below the goal of 6.3 million set in the North American Waterfowl Management Plan (NAWMP), causing concern among biologists and hunters. We summarize issues of concern, hypotheses for factors contributing to the population decline, and research and management needs recommended by participants of the Scaup Workshop, held in September 1999. We believe that contaminants, lower female survival, and reduced recruitment due to changes in food resources or breeding-ground habitats are primary factors contributing to the decline. These factors are not mutually exclusive but likely interact across seasons. Workshop participants identified seven action items. We need to further delineate where declines in breeding populations have occurred, with a primary focus on the western Canadian boreal forest, where declines appear to be most pronounced. Productivity in various areas and habitats throughout the breeding range needs to be assessed by conducting retrospective analyses of existing data and by intensive field studies at broad and local scales. Annual and seasonal survival rates need to be determined in order to assess the role of harvest or natural mortality. Effects of contaminants on reproduction, female body condition, and behavior must be investigated. Use, distribution, and role of food resources relative to body condition and reproduction need to be examined to better understand seasonal dynamics of nutrient reserves and the role in reproductive success. Affiliations among breeding, migration, and wintering areas must be assessed in order to understand differential exposure to harvest or contaminants, and differential reproductive success and recruitment. Biologists and agencies need to gather and improve information needed to manage greater and lesser scaup separately; this includes monitoring the breeding populations of each species separately, closer examination of existing data to improve surveys and data collection, and re-evaluation of the NAWMP population goal. These complex issues will require extensive cooperation and communication among many agencies and organizations in North America.
Key words: Aythya affinis, Aythya marila, management, population, research needs, trends
This resource is based on the following source (Northern Prairie Publication 1088):
Austin, Jane E., Alan D. Afton, Michael G. Anderson, Robert G. Clark, Christine M. Custer,
Jeffrey S. Lawrence, J. Bruce Pollard, and James K. Ringelman. 2000. Declining
scaup populations: issues, hypotheses, and research needs. Wildlife Society Bulletin
28(1):254-263.
This resource should be cited as:
Austin, Jane E., Alan D. Afton, Michael G. Anderson, Robert G. Clark, Christine M. Custer,
Jeffrey S. Lawrence, J. Bruce Pollard, and James K. Ringelman. 2000. Declining
scaup populations: issues, hypotheses, and research needs. Wildlife Society Bulletin
28(1):254-263. Jamestown, ND: Northern Prairie Wildlife Research Center Online.
http://www.npwrc.usgs.gov/resource/birds/dscaup/index.htm (Version 18SEP2000).
Table of Contents
- Introduction
- Delineate where declines in breeding populations have occurred
- Assess productivity in various areas and habitats throughout the breeding range
- Assess annual and seasonal survival rates
- Investigate effects of contaminants on reproduction, female body condition, and behavior
- Examine use, distribution, and role of food resources relative to body condition and reproduction
- Determine affiliations among breeding, migration, and wintering areas
- Gather and improve information needed to manage greater and lesser scaup separately
- Conclusions
- Acknowledgments
- Literature Cited
- About the Authors
- Figure 1 -- Annual estimates and 95% confidence intervals of numbers of breeding scaup.
1 Address for Jane E. Austin: United States Geological Survey, Northern Prairie Wildlife Research Center, Jamestown, ND 58401, USA.
2 Address for Alan D. Afton: United States Geological Survey, Louisiana Cooperative Fish and Wildlife Research Unit, Louisiana State University, Baton Rouge, LA 70803-6202, USA.
3 Address for Michael G. Anderson: Ducks Unlimited Canada, Institute for Wetland and Waterfowl Research, Stonewall, MB R0C 2Z0, Canada.
4 Address for Robert G. Clark: Environment Canada, Canadian Wildlife Service, Prairie and Northern Wildlife Research Center, Saskatoon, SK S7N 0X4, Canada.
5 Address for Christine M. Custer: United States Geological Survey, Upper Midwest Environmental Sciences Center, LaCrosse, WI 54602, USA.
6 Address for Jeffrey S. Lawrence: Minnesota Department of Natural Resources, Wetland Wildlife Populations and Research Group, Bemidji, MN 56601, USA.
7 Address for J. Bruce Pollard: Ducks Unlimited Canada, Institute for Wetland and Waterfowl Research, Stonewall, MB R0C 2Z0, Canada.
8 Address for James K. Ringelman: Ducks Unlimited, Inc., Great Plains Region Office, Bismarck, ND 58501, USA.
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