Time-activity budgets of Harlequin Ducks molting in the Gannet Islands, Labrador

We studied the time-activity budgets of Harlequin Ducks (Histrionicus histr ionicus) molting at the Gannet Islands, Labrador in the summer of 1998. For the entire population, a large proportion of time was spent hauled our of the water (61.4%), and resting (53.5%). Only a small proportion of time was spent foraging (11.6%). Male Harlequin Ducks undergoing the pre-basic molt were hauled out of the water significantly more (92.2%) than males in basi c plumage (8.1%). Males undergoing the pre-basic body feather molt foraged significantly less (1.7%) than males in basic plumage (17.7%). Harlequin Du cks do not appear to increase their food intake to meet the nutritional req uirements of molt. Instead they may try to reduce thermoregulatory and main tenance costs by engaging in activities that do not consume much energy, an d by staying out of cold water while their plumage is not intact. Furthermo re, they may deliberately lose body mass while molting to regain the abilit y to fly at an earlier stage of wing molt.