LE3 .A278 2016

2016

Mallory, Mark
Robertson, Gregory

Acadia University

Master of Science

Masters

Biology

Biology

American black ducks (Anas rubripes) remain a species of international concern in North America as the population size has been reduced by ~50% since the 1950s. Atlantic Canada is the northern limit of black duck wintering range, and to fill knowledge gaps on black duck winter ecology, I examined black duck winter diet and body condition in Atlantic Canada in rural, semi-urban (agricultural), and urban habitats. Diet was examined through an analysis of gut contents and stable isotope analysis of blood. Diet differed significantly among the three habitats, with rural ducks relying mainly on molluscs and seeds, while urban ducks relied on corn and other vegetation. Semi-urban ducks appeared to rely on molluscs early in he winter, and then shifted their diet to feed provided by farmers late in the winter.Both wild and anthropogenic food supplies are essential to wintering black ducks in Atlantic Canada. Body condition was assessed by examining carcass composition, and using a scaled mass index (SMI). Carcass composition did not differ between rural and urban black ducks, and body mass and fat reserves significantly declined through the winter. When carcass composition of the black ducks in my study was compared to that of black ducks wintering farther south, black ducks in Atlantic Canada are significantly structurally smaller and lighter than those wintering in Maine and Virginia, but are proportionally fatter. Females had a higher SMI than males, and despite their distinct diets, SMI did not differ among rural, semi-urban, and urban ducks. In determining the winter carrying capacity for black ducks in Atlantic Canada, urban and agricultural areas along with natural coastal areas should be considered as essential wintering habitats

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https://scholar.acadiau.ca/islandora/object/theses:1502