The gizzard worm, Amidostomum acutum (Lundahl, 1848) Seurat, 1918 in common eiders (Somateria mollissima L.) in the Netherlands

A study was made on the prevalence of Amidostomum acutum in the gizzard of the common eider (Somateria mollissima L.) in the Netherlands. The investigated birds were found dead along the Dutch coast in the winter of 2001/ 2002. From the dead birds collected at two localities, the North Sea coast near the Hondsbossche Zeewering and the Wadden Sea coast of the isle Texel, 50 eiders were selected. These 50 birds consisted of ten adult males, ten adult females, 15 juvenile males and 15 juvenile females. All birds were infected with A. acutum. The number of worms varied from four to 826. There were no significant differences in worm numbers in birds from both localities. Adult birds had significantly more worms (av. 150) than juveniles (48). Adult males had significantly more worms (av. 202) than adult females (98). These differences were found in both localities. The possible role of A. acutum in the mass mortality among the eiders is discussed