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Nature Notes: Common Eider

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By Ed Robinson

common-eider-adult-maleNow that winter is here, welcome back one of Harpswell’s more spectacular birds. The largest duck in Maine is known as the “common eider” (somateria mollisima) to distinguish it from the more unusual king and spectacled eiders, but there is nothing common about these beauties. A full grown adult can reach 28″ long, with a wing span of 43″ and a weight of 7 pounds. The males in breeding plumage are a stunning black and white with distinctive light green patches on the nape of their neck and the top of their bill. Like most female birds, the hen is not so flashy, but I find her rich browns, tans and cinnamons quite lovely.

Eiders nest in colder climates across North America, Europe and Siberia, but Maine has approximately 28,000 breeding pairs, according to the National Audubon Society. They nest on the tundra or in Maine on rocky ledges and islands, often returning to the same nest site annually. Nests will have several eggs and a lining of that famed eider down, plucked from the female’s breast. I can always tell when eiders are back in our cove for the spring nesting season. The birds have a pleasant “ah-ooo” sound, but when your back is to the water it sounds like someone moaning or cooing along the shore.

The ducklings leave the nest within a day of hatching and are capable of swimming and feeding on their own. The diet of eiders is another distinguishing feature, since they feed primarily on crustaceans and molluscs, with periwinkles, mussels and clams being their favorites. Molluscs are swallowed whole, and the shells are broken up in the duck’s gizzard.

Eiders are ungainly on land, since like most diving ducks, their legs are set well back on their body. But in the water they are strong swimmers, capable of staying submerged over 1 minute and diving below 100 feet. Eiders also excel in the air. Those powerful wings can propel an eider at speeds up to 70 mph!

Large die-offs knocked down eider populations in the 1990’s due to changes in Arctic ice movements but today their population is robust at 1.5-2 million in North America. So, bundle up this winter and walk a rocky shore and you are sure to see these distinctive ducks foraging along Harpswell’s coastline.

December 2012