We studied the impact of human disturbances on the feeding activities of Common Eiders Somateria mollissima wintering in Southwest Greenland. Eider activity and human disturbances (fast moving, open boats) were recorded during 9 days of observations in mid and late winter 2002. When most heavily disturbed, the feeding activity in the study area was reduced up to 60% on a daily basis. At the same time locomotion activity tripled. Logistic regression analyses showed that eiders attempted to compensate for lost feeding opportunities by rescheduling more feeding to periods where feeding conditions were relatively less profitable with respect to other variables. When undisturbed, eiders avoided feeding during high tide and intensified feeding at the start and at the end of the day, but these tendencies were levelled out if eiders were disturbed. When disturbed, the time interval and the distance to the last disturbance were both significant explanatory variables for the feeding activity. There was a cumulative effect of repeated disturbances on the feeding activity if disturbances were close in time and space (<1 h, <1 km). The day with the highest number of disturbances coincided with observations of nocturnal feeding the following night and may indicate that a critical threshold of disturbances was reached where eiders could not rely on a diurnal feeding strategy.