The movement patterns, range areas and energetics of canvasbacks (Aythya valisineria) wintering in the upper Chesapeake Bay, Maryland, were investigated. Eighty-seven juvenile female canvasbacks were radio-tracked between 30 December 1988 and 25 March 1989. Diurnal time and energy budgets were constructed for a time of day-season matrix for canvasbacks using riverine and main bay habitats. Canvasbacks were very active at night, making regular and often lengthy crepuscular movements (x = 11.7 km) from near shore habitats during the day to off shore habitats at night. Movement patterns were similar for birds using habitats on the eastern and western shores of the Bay. Canvasbacks had extensive home ranges averaging 14,286 ha, and used an average of 1.97 core areas. Sleeping was the predominant diurnal behavior. Telemetry indicated that canvasbacks actively fed at night. Canvasbacks spent more time in active behaviors (e.g. swimming, alert) on the eastern shore than on the the western shore. Similarly, canvasbacks were more active during daytime hours at locations where artificial feeding occurred. Behavioral patterns were only weakly correlated with weather patterns. Canvasbacks appeared to reduce energy expenditure in mid-winter by reducing distances moved, reducing feeding activities and increasing the amount of time spent sleeping. This pattern was observed even though 1988-89 mid-winter weather conditions were very mild. / Master of Science

During the winter 1988-89, diurnal and nocturnal habitat use by juvenile female canvasbacks wintering on the upper Chesapeake Bay was determined. Radio-implanted canvasbacks used shallow water (0-2 m) areas near artificial feeding sites during the day, and deeper water (2-6 m) that had an abundant (> 200/m²) population of small (< 25 mm) Macoma balthica at night. Because of poorer Macoma populations on the east side of the Bay, canvasbacks there may feed more during the day and are in lower Macoma densities at night than west shore canvasbacks. Management of Chesapeake Bay canvasback populations should focus on providing natural foods and rest areas. / Master of Science