Size selection of common mussels, Mytilus edulis , by common eiders, Somateria mollissima : energy maximization or shell weight minimization?

• Published in: Canadian Journal of Zoology
• Main Authors: Bustnes, Jan Ove, Erikstad, Kjell Einar
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1990
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Norway; Northern Norway; Somateria mollissima
• Online Access: http://dx.doi.org/10.1139/z90-318; http://www.nrcresearchpress.com/doi/pdf/10.1139/z90-318

Prey size selection by common eiders, Somateria mollissima, preying on common mussels, Mytilus edulis, in northern Norway is described. The mean length (± 1 SD) of mussels preyed upon was 13.9 ± 5.7 mm (range 3.5–38.1 mm). The dry flesh weight as a percentage of the total dry weight ranged from 4.2 to 8.6% in different body-length categories and was greatest in the mussels most frequently fed upon. There was a close negative correlation between the size of mussels fed upon and the estimated total shell weight that birds had to ingest to obtain their daily requirement of food (r s = −0.86). A hypothesis is proposed that common eiders select mussels of certain size classes to minimize the daily shell weight intake.