Declines of Greater and Lesser Scaup Populations: Issues, Hypotheses, and Research Directions
Summary Of Issues
Following presentations on the issues discussed above, workshop participants generated a list of issues (not prioritized) to aid further discussions (Table 1). Participants grouped these issues into 4 main questions, similar to hypotheses outlined in Afton and Anderson (in review) for detailed discussion on how to direct future research and survey efforts:
- Has reproduction or survival of scaup changed sufficiently to cause population
declines and, if so, what is the cause(s)?
- Have changes in the western Canadian boreal forest resulted in reduced
reproductive success of scaup?
- Have physiological changes, including nutrient acquisition patterns and
contaminants, affected reproductive success of scaup?
- What information is needed to manage greater and lesser scaup separately?
The sections below summarize the discussions and recommendations from each discussion group. Group leaders were R. Clark, B. Pollard, C. Custer, and J. Lawrence, respectively.
Table 1. List of issues generated from presentations and discussions during the Scaup Workshop.
- Contaminants - breeding
- Contaminants - winter/migration
- Contaminants - nutritional impact
- Adequacy of winter surveys
- Adequacy of breeding surveys
- Changes in migrational routes and resources
- Are population declines real?
- Detection of future declines
- Reproductive success
- Breeding habitat changes
- Annual survival (adult females), seasonal partition of survival
- Predation
- Changing food resources - quality and quantity
- Proportion of greater and lesser scaup by strata
- Changes in boreal forest habitat
- Boreal forest fire impacts
- Banding samples - survival rates
- Role of hunting mortality
- Standardized harvest survey data in US and Canada
- Climate change
- Nutrient reserve acquisition (timing, location)
- Disease / parasites / health
- Change in population as function of vital rates
- Postbreeding ecology
- Site fidelity (breeding and winter)
- Differences between boreal forest and prairie birds in their breeding ecology, breeding parameters, and nutrient dynamics
- Coincidence of population changes in similar species
- Compare to similar species with stable populations
- Disturbance factors, affecting access to food resources, etc; including boating, hunting activities
- Appropriateness of NAWMP goal
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