If you walk along the Cape Cod Canal or along the Sandwich beaches you will find huge rafts of common eider ducks. These northern ducks gather here by the thousands late in the fall and stay here all winter. Although smaller groups may be found all along the coast of the Cape each winter these mussel loving birds really congregate in this area due to the huge concentration of mussels, sea urchins and other favorite foods.The beautiful males or drakes are marked with lovely and distinct black and white patterns.
The females are also lovely but a more muted brown. Eiders nest much farther north than the Cape (though it is thought some are nesting here now) and are colonial nesters, meaning they like to nest in large groups. The color of the females helps them blend into the sand or dirt they scrape a nest in.
In any flock of eiders you may see what look like oddly marked birds that are neither marked like males or females. These are the immature or young ducks that haven't got their full plumages yet.
At one point eiders were hunted almost to extinction for their beautiful feathers. If you've heard of eider down, that referred to the soft down from the eider duck's breast. Coats and jackets were also made from their skins. Today these birds are safe from this sort of hunting and their populations have made a good come back.