Unusual Migration Mortality of King Eiders in Central Baffin Island

Abstract

-In October 1999, approximately 110 King Eiders (Somateria spectabilis) were found on the ground in the middle of Baffin Island, indicating that these birds had been following an overland migration. The composition of the flock was mixed in both sex (44% female, 56% male) and age of birds (62% hatch year, 38% after hatch year). Approximately 40 birds flew off after resting for six days on the frozen ground. Of the remaining birds that died, predators ate about 15, and 55 were recovered by staff from a local radar site. All eider carcasses carried fat reserves, although there were differences in body mass related to age and sex. Most birds had injuries consistent with crashing into an object at high speed, but in the absence of any obvious vertical obstacles in this region, it appears that this flock flew into the ground during conditions of poor visibility, perhaps facilitated by the formation of cataracts in their eyes. Received 28June 2001, accepted 17 August 2001.