The behaviour of moulting King Eiders Somateria spectabilis

Abstract

Activity budgets and distribution patterns of King Eiders were studied at Disko Island, West Greenland during the moulting season of July to September, and compared with the activity budgets of non-moulting King Eiders. King Eiders were generally active in the daylight hours, and spent most of the night and a period at mid-day resting. The feeding intensity peaked early and late in the day, with no marked tidal influence on the feeding pattern. The amount of time devoted to diurnal feeding increased during the moulting period, and was negatively correlated with daylength. There was no evidence of increased feeding intensity by moulting birds compared to non-moulting birds. Moulting King Eiders devoted more time to comfort movements than non-moulting birds. Ice conditions and daylength are suggested to be ultimate factors affecting the timing of moult.