The Common Eider is a common species of sea duck in northern coastal regions of North America, Europe and eastern Siberia. A common breeder in Maine, Common Eiders nest as far south as Massachusetts in New England. Common Eiders are important members of arctic breeding bird communities well to the north of us as well.
Common Eiders withdraw from their more northerly breeding areas after nesting and winter in coastal flocks. Winter aggregations may number in the thousands. In Maine, this species is present year-round.
Common Eiders are distinctive birds, often recognizable merely by their silhouette. The combination of a long, sloping bill (think ski jump), long neck and peaked head give them a distinctive look. At a length of two feet, Common Eiders are among our biggest ducks.
Adult drakes are subtly beautiful birds. The crown is black but the cheeks, neck and dorsal body are mostly white. A close look in favorable light reveals a light green wash on the posterior side of the face and nape. The mostly black wings contrast with the white sides when an eider is on the water. The bill is a dull yellow.
Like most ducks, the adult females are much less brightly marked. The body is barred with irregular dark and light brown stripes. The head is mostly brown.
First-year males are highly variable with brown heads like females but with splotches of white and brown on the dorsal surface. The breast is white.
Common Eider females make a nest on rocky islands, not far above the high tide mark. A female plucks down from her breast to line the nest. The down used to create soft, warm pillows, coats and sleeping bags often comes from eider down.
Harvesting eider down is typically done after the nesting season. A down collector simply gathers the down from the nest once the young eiders have hatched. However, synthetic insulating materials have been developed with comparable insulating properties to eider down. These synthetic products are relatively cheap to produce so an eider down-filled vest or coat will cost you a pretty penny compared to a product made from a synthetic material.
By the way, some down used for insulation comes from geese. That down has to be plucked directly from the geese. Goose down is inferior to eider down in insulating properties.
A hen eider may lay up to 14 eggs. When the ducklings hatch, they are covered with a down coat and leave the nest soon after hatching.
Once the ducklings have hatched, they aggregate into crèches of 100 birds or more. These eiders are watched over by the moms as well as non-breeding females.
The ducklings start to form their contour feathers in their second week and complete feather growth by seven weeks after hatching. They take their first flight nine or ten weeks after hatching.
Common Eiders dive in search of invertebrate food from the sea bottom. Mussels are one of the most common prey items taken although crabs and sea urchins are important components of their diet as well. An eider swallows a mussel whole, crushing the shell of the mussel in its powerful gizzard. For a crab, an eider removes the legs first and then swallows the de-legged crab for crushing in the gizzard.
The fondness of Common Eiders for mussels poses a challenge for mussel mariculture. Not surprisingly, the dense aggregation of mussels attracts eiders. Nets seem to be the only practical way to protect the mussels from the eiders and other sea ducks.
Common Eiders are doing well now with an estimated population of two million birds in North America and Europe. Our New England population was nearly decimated by market hunters by the end of the 19th century. Fortunately, the eiders have recovered.
[Originally published on October 18, 2015]