Northern Prairie Wildlife Research Center
Declining Scaup Populations:
Issues, Hypotheses, and Research Needs
Jane E. Austin1, Alan D. Afton2, Michael G.
Anderson3, Robert G. Clark4, Christine M. Custer5,
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
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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