Lesser scaup breeding ecology in the Canadian parklands/ by David Nelson Koons.

Thesis (M.S.) -- Montana State University -- Bozeman, 2001.

Includes bibliographical references.

The continental population of lesser scaup (Aythya affinis) has declined over the past 20 years and causes of the decline have not been identified. To identify factors possibly related to the decline, I designed and conducted a study to estimate demographic vital rates of lesser scaup and to compare those rates to historic vital rates for a local population (Erickson, Manitoba). The local population had been well studied before the recent declines of scaup numbers occurred. I also developed a model to examine population growth and its relation to vital rates. For my study population, I found that nesting success,duckling survival, and possibly breeding-season survival of mature females were lower than historical estimates. I found that nesting success increased with period-of-year, was higher for over-water nests,and was negatively related to vegetation density. The majority (86%)of duckling mortality occurred during the first week post-hatch.Eighty-three percent of female mortality occurred during the nesting period, and female survival during the nesting period was negatively related to vegetation density. Further, analytic perturbation of my population model indicated that the local population is declining, and that breeding-season survival of mature females and nesting success have the strongest potential to affect population growth. Thus,declines in these vital rates have likely caused the local decline of scaup numbers. Strategies designed to increase breeding-season survival of mature females and nesting success wil likely have a bigger impact on lesser scaup population growth rate at Erickson than strategies designed to manage other vital rates.