Postbreeding ecology of Barrow's Goldeneyes in Northwestern Alberta

I studied remigial molt phenology, body mass dynamics, foraging effort, and survival of Barrow’s Goldeneyes (Bucephala islandica) on Cardinal and Leddy Lakes, Alberta to evaluate whether the postbreeding period imposed nutritional or demographic constraints that could affect population dynamics. Adult male Barrow’s Goldeneyes, the predominant cohort on the study sites, arrived by mid-June and departed by mid-November. Remigial molt lasted 39 days during which body mass increased despite low foraging effort by adult males; mass and foraging patterns differed between lakes. Cumulative survival of adult males during remigial molt was high (95%). Taken together, these results indicate that remigial molt was not a period of nutritional limitation or high mortality risk for Barrow’s Goldeneyes and that molt strategy was responsive to local conditions. Cumulative adult male survival during fall staging (71%) was substantially lower than during remigial molt with at least half of mortalities on Cardinal Lake attributed to hunting.