Text and photos by Peter Vankevich
Winter on Ocracoke is a good time of the year to see rare birds. Most of them venture here from their northern seasonal ranges.
The Common Eider (Somateria mollissima) is one of these, and two–an adult female and an immature male–were seen recently in Silver Lake harbor. Apart from the rare Muscovy duck, found occasionally along the southern border of Mexico and south Florida, the Common Eider is the largest duck in North America. Most of the Common Eiders that make it to the coastal waters of North Carolina are adult females and immature males and females.
The adult male is unmistakable, with its black sides and crown, white back and breast and sloping yellow bill. When the lighting is just right, it shows a green nape. Immature males are brown with varying amounts of white around the neck and back. Females are russet-brown to gray with barred dark brown lines on their backs, chests, breasts, sides and flanks and a sloping head and olive-to-gray bill.
Circumpolar, eiders inhabit much of the marine areas of eastern and northern Canada and Alaska. In the eastern United States, they nest in large numbers in Maine where they can be found off the coast year-round. They breed in much smaller numbers as far south as Massachusetts.
In Europe, they can be found in the north including along Barents Sea of northern Russia, Norway, the Baltic Sea, the North Sea in Scotland and England and south to northern France.
These sea ducks are colonial nesters, mostly on marine islands and islets and rarely on freshwater lakes. Nesting on small islands can limit the potential impact of mammalian predators, but they must deal with avian predators such as large gulls, jaegers, crows and ravens, all of which will prey on eggs and young hatchlings. Colonies can range from pairs in the tens, hundreds and even thousands.
In the east, they winter from Greenland to the Gulf of St. Lawrence and south along the Atlantic Coast to Virginia, with a few migrating into the Carolinas and more rarely farther south. In the west, their winter range extends south to southern Alaska.
Deep divers, they can submerge for long periods to forage on mollusks, especially blue mussels, and sea urchins and crabs.
When alarmed, males and females emit a series of hoarse, grating, kor-korr-korr notes. At times, flocks can be quite noisy, especially on warm days in spring near nesting colonies. Drakes give a haunting, cooing call not unlike that of domestic pigeons; their call can travel great distances over water on calm days.
During courtship, the male displays include much upward tossing of the head, cooing, neck-stretching, and ritualized wing-flapping.
When preparing the nest, the hen preens the down from her belly and places it into the nest. The final accumulation of down can be quite bulky, completely surrounding eggs or even covering them when hens leave the nests unattended.
These down feathers are light-weight and have unequaled insulating properties, making eiderdown prized worldwide for use in high-end comforters, pillows, sleeping bags and outdoor garments.
The eiderdown industry is well developed in Iceland, where, through careful husbandry over many generations, eiders have become tolerant of the presence of the harvesters, allowing down to be collected with minimal disturbance to nearby still-nesting hens.
These days, in North America, eiderdown collecting is practiced commercially only in the St. Lawrence estuary and, to a limited extent, in a few Inuit communities in the eastern Canadian Arctic.
Clutches average three to five eggs, but upward of 14 can occur. One study indicated that larger clutches are likely the result of egg-dumping by other females. Incubation takes about 26 days.
Hatchlings are precocial, which means they are hatched in an advanced state–fully covered with down, have open eyes and leave the nest in about 24 hours to begin feeding themselves while staying close to the mother hen.
The mothers lead the young to water and may be accompanied by other nonbreeding hens, called “aunts.” If approached by a would-be predator such as a large gull, the mother assumes a defensive posture with open wings and tail spread and moves the head up and down repeatedly. The hatchlings will rush under her for protection.
The ducklings eat different foods from the adults, being dependent at first on small, soft prey such as insects, amphipods, and small gastropods such as periwinkles.
As with most sea ducks, which nest in stark, cold and dangerous habitats, reproductive success can vary from year-to-year.
The longest life span so far recorded for Common Eider is 21 years and 4 months for a female from the St. Lawrence estuary.
Three other eiders, the King, Spectacled and Steller’s Eider, also breed in North America. The King Eider, which breeds in the arctic, is much rarer to North Carolina than the Common Eider. There are no North Carolina records for Spectacled or Stellar’s Eiders, which occur in the northern latitudes along coastal Alaska and easternmost Russia, as well as in the Bering Sea. These two are rarely seen outside their breeding and wintering ranges in that general region.
Listen: Go to the Internet Bird Collection (IBC) and click here
When to see: Fall into winter
Where: Sound, inlets, ocean and Silver Lake harbor