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Lesser scaup population dynamics : What can be learned from available data? / David N. Koons, Jay J. Rotella, David W. Willey, Mark Taper, Robert G. Clark, Stuart Slattery, Rodney W. Brook, Robin M. Corcoran, and James R. Lovvorn.

By: Contributor(s): Material type: TextTextSeries: Avian Conservation and Ecology. 1(3) 6 Publication details: 2006.Description: illustrations ; 28 cmLOC classification:
  • KOO
Online resources: Summary: Populations of Lesser Scaup (Aythya affinis) have declined markedly in North America since the early 1980s. When considering alternatives for achieving population recovery, it would be useful to understand how the rate of population growth is functionally related to the underlying vital rates and which vital rates affect population growth rate the most if changed (which need not be those that influenced historical population declines). To establish a more quantitative basis for learning about life history and population dynamics of Lesser Scaup, we summarized published and unpublished estimates of vital rates recorded between 1934 and 2005, and developed matrix life-cycle models with these data for females breeding in the boreal forest, prairie-parklands, and both regions combined. We then used perturbation analysis to evaluate the effect of changes in a variety of vital-rate statistics on finite population growth rate and abundance. Similar to Greater Scaup (Aythya marila), our modeled population growth rate for Lesser Scaup was most sensitive to unit and proportional change in adult female survival during the breeding and non-breeding seasons, but much less so to changes in fecundity parameters. Interestingly, population growth rate was also highly sensitive to unit and proportional changes in the mean of nesting success, duckling survival, and juvenile survival. Given the small samples of data for key aspects of the Lesser Scaup life cycle, we recommend additional research on vital rates that demonstrate a strong effect on population growth and size (e.g., adult survival probabilities). Our life-cycle models should be tested and regularly updated in the future to simultaneously guide science and management of Lesser Scaup populations in an adaptive context.

Includes bibliographical references.

Populations of Lesser Scaup (Aythya affinis) have declined markedly in North America since
the early 1980s. When considering alternatives for achieving population recovery, it would be useful to
understand how the rate of population growth is functionally related to the underlying vital rates and which
vital rates affect population growth rate the most if changed (which need not be those that influenced
historical population declines). To establish a more quantitative basis for learning about life history and
population dynamics of Lesser Scaup, we summarized published and unpublished estimates of vital rates
recorded between 1934 and 2005, and developed matrix life-cycle models with these data for females
breeding in the boreal forest, prairie-parklands, and both regions combined. We then used perturbation
analysis to evaluate the effect of changes in a variety of vital-rate statistics on finite population growth rate
and abundance. Similar to Greater Scaup (Aythya marila), our modeled population growth rate for Lesser
Scaup was most sensitive to unit and proportional change in adult female survival during the breeding and
non-breeding seasons, but much less so to changes in fecundity parameters. Interestingly, population growth
rate was also highly sensitive to unit and proportional changes in the mean of nesting success, duckling
survival, and juvenile survival. Given the small samples of data for key aspects of the Lesser Scaup life
cycle, we recommend additional research on vital rates that demonstrate a strong effect on population
growth and size (e.g., adult survival probabilities). Our life-cycle models should be tested and regularly
updated in the future to simultaneously guide science and management of Lesser Scaup populations in an
adaptive context.

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