The king eider is a type of duck common to the coastal regions of the Arctic. These ducks are known for the vivid, unusual coloring of the males during breeding season, the massive size of their flocks, and their ability to dive to great depths in order to feed. Compared to many other sea ducks, the king eider is considered fairly large, with the average weight being around 4 pounds (1.8 kg).
During mating season, the coloring of the male king eider changes dramatically as they shed their brown and black feathering for plumage that is much more vivid. The breeding plumage of males includes blue feathering on their necks and foreheads, with much of their facial area covered in green. Males have bright orange bills, and during mating season, their bills are accented by an orange protrusion that develops just above the crest. The body of the male ducks turns white, with black feathering covering their wings and back. Female king eiders, sometimes referred to as queens, have year round plumage of brown and black, with bills that are pale yellow or gray.
The most common habitats for the king eider are the coastal regions of northern Canada, Alaska, Russia, and Greenland. Breeding season is during the summer months, and during this time, the flocks are generally found in the northernmost parts of these countries. During the winter, the king eider flies south, but the ducks usually remain in northern climates, typically staying close to the sea. King eiders usually live in flocks ranging in size from 10,000 to 50,000 ducks. These flocks may stay together for many years, though between migrations, the flocks often scatter into smaller groups.
Female eiders are typically mature enough to breed by the time they reach three years of age. They usually lay four to five eggs over a period of about seven days. The eggs incubate for just under a month, during which time the female duck stays with the eggs, rarely leaving the nest. Female eiders do not eat during this incubation period.
The typical diet of a king eider consists of plankton and small sea snails and fish. They must swallow their food whole, and use their gizzards to break up the food before it enters their digestive tracts. In order to find food, the eiders can dive up to 150 feet (45 m). Seawater is a large part of their diet, but when available, the ducks prefer fresh water.