Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

No description available.

Thesis (Master's)--University of Wisconsin, 1947. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [157]-163).

Thesis (M.S.)--University of Maine, 1987. / Includes vita. Includes bibliographical references (leaf 54). Available also in electronic format on the Internet.

No description available.

No description available.

Habitat selection by breeding black ducks (Anas rubripes) was studied in Antigonish County, Nova Scotia during April-September 1990 and 1991. / Black duck pairs selected deciduous shrub ponds and sparsely vegetated ponds and avoided estuarine marsh and large lake habitat. Hens with broods preferred the deciduous shrub habitat while they avoided large lakes. / Black duck pairs appeared to use the distance to a brood-rearing pond as a cue in site selection. The closer a pond was to a suitable rearing pond the more likely it was occupied by a pair, regardless of food or cover resource availability. Black ducks, however, likely used site attributes such as the perimeter of the pond, the availability of aquatic invertebrates and the relative abundance of alder, willow and dead timber as cues in the selection brood-rearing habitat. / Black duck duckling survival, an estimate of recruitment, was the highest on preferred deciduous shrub ponds. Duckling survival was also higher on ponds with only one brood as opposed to ponds with several broods. / The most productive habitat for black ducks in the Antigonish study area were isolated, deciduous shrub ponds influenced by beaver activity. Black duck population numbers can be enhanced by managing local beaver populations.

No description available.

AN ABSTRACT OF THE THESIS OF Benjamin S. Lewis Jr., for the Master of Science degree in ZOOLOGY, presented on December, 2, 2015 at Southern Illinois University Carbondale. TITLE: DETERMINING FOOD RESOURCES FOR AMERICAN BLACK DUCKS WINTERING AND SPRING STAGING ON THE EASTERN SHORE OF VIRGINIA MAJOR PROFESSOR: Dr. Michael W. Eichholz I evaluated food availability and food preference for American black ducks (Anas rubripes) wintering and spring staging on the Eastern Shore of Virginia during 2006–2007 and 2007–2008. I estimated food availability by taking core and sweep net sample at 78 sites selected by a stratified random sample throughout our study area, representing 4 dominant wetland habitat types. Seed and invertebrate biomass found in each of these samples were converted to measurements of kilograms per hectare. I found that salt marsh and mudflat habitats contained the highest amount of invertebrate biomass, while freshwater habitats contained the highest amount of seed biomass. I estimated food preference by collecting crop samples from 76 foraging black ducks. Animal matter made up 73% of the aggregate percent biomass of all foods eaten by black ducks. Foods found in black duck crops were compared to their availability in the environment and classified as either selected for, avoided or consumed relative to their availability. Although they were not found to be the most abundant foods, amphipods (Gammarus spp), salt marsh snails (Melampus bidentatus) and ribbed mussels (Geukensia demissa) were foods selected for in black duck wintering habitats. These food items are found most predominantly in salt marsh and mudflat habitats. As may be expected these areas are identified as the most important habitats for black ducks wintering on the Eastern Shore of Virginia. Results from this study provide energetic supply data for bioenergetically based habitat conservation for black ducks in Virginia and in the Atlantic Flyway. I found that the density of food items available for wintering black ducks were lower than densities found in in the more northern wintering range of the black duck and considerably lower than estimates from the wintering regions of other species of dabbling ducks. By concurrently measuring food selection and availability I was also able to reliably determine food preference. Removing avoided food items from food availability estimates provides more accurate estimates of preferred food biomass and it is important for bioenergetically based habitat models to use estimates of preferred food biomass in determining habitat objectives. I found that when avoided food items are removed, estimates of available food biomass decrease substantially, (up to 97%) further emphasizing discrepancies in estimates of food availability between coastal black duck wintering areas and estimates from the wintering regions of other species of dabbling ducks.