Ecology of lesser scaup and amphipods in the upper-midwest : scope and mechanisms of the spring condition hypothesis and implications for migration habitat conservation / Michael J. Anteau.

Thesis(Ph.D.)--Louisiana State University, 2006.

Includes bibliographical references.

I tested the scope of the Spring Condition Hypothesis in explaining the continental population decline of lesser scaup (Aythya affinis;hereafter scaup) and explored potential mechanisms affecting female body condition to assist conservation efforts for population recovery.Lipid reserves of females currently are lower than historical values during spring migration throughout Iowa, Minnesota, and North Dakota;females catabolized lipids throughout this area (indexed by concentrations of plasma-lipid metabolites, which accounted for 75% of the variation in mass change). My results indicate that a large segment of the continental scaup population likely is affected by decreased lipid reserves, which could cause reductions in breeding propensity and reproductive success. Hepatic cadmium was negatively correlated with lipid reserves of females during spring migration;however, current cadmium concentrations only accounted for 11% of the observed decrease in lipid reserves of females between Illinois and Minnesota. Wetland use by scaup was positively correlated with amphipod densities throughout the upper-Midwest, indicating a preference for amphipods. Amphipod densities were markedly lower (1-12 m3) and scaup were consuming fewer amphipods in the upper-Midwest relative to historical records...