The white-winged scoter is a large sea duck. The genus name is derived from Ancient Greekmelas "black" and netta "duck". The species name commemorates French ornithologist Côme Damien Degland.
Description
The white-winged scoter is one of three North American scoter species and the largest species of scoter. It is characterised by its bulky shape and large bill. Females range from and, averaging and. She is brown with pale head patches. The male ranges from and from, averaging and. He is all black, except for white around the eye and a white speculum. This scoter's bill has a black base and a large knob. There are a number of differing characteristics of the Stejneger's scoter and the white-winged scoter. Males of the white-winged scoter have browner flanks, dark yellow coloration of most of the bill and a less tall bill knob, approaching the velvet scoter. Stejneger's scoter has a very tall knob at the base of its mostly orange-yellow bill. Females are identical in the field. The Latin binomial commemorates the French zoologist Dr. Côme-Damien Degland.
Taxonomy
It was formerly considered to be conspecific with the velvet scoter, and some taxonomists still regard it as so. These two species, the Stejneger's scoter, and the surf scoter, are placed in the subgenus Melanitta, distinct from the subgenus Oidemia, black and common scoters. Stejneger's scoter was suggested to be a full species, according to a new study.
Distribution
The white-winged scoter breeds over the far north of North America. It winters further south in temperate zones, on the Great Lakes, the coasts of the northern United States and the southern coasts of Canada.. It forms large flocks on suitable coastal waters. These are tightly packed, and the birds tend to take off together. It has occurred as a vagrant in Europe, including Scotland, Iceland, Norway and Ireland,
Behavior
Breeding
The lined nest is built on the ground close to the sea, lakes or rivers, in woodland or tundra. 5–11 eggs are laid. The pinkish eggs average in breadth, in length and in weight. The incubation period can range from 25 to 30 days. After about 21 days, neighboring females may start to behave aggressively towards other nesting females, resulting in confusion and mixing of broods. By the time she is done brooding, a female may be tending to as much as 40 offspring due to the mixing from these conflicts. The female will tend to her brood for up to 3 weeks and then abandon them, but the young will usually stay together from another 3 weeks. Flight capacity is thought to be gained at 63 to 77 days of age.
Food
In freshwater, this species primarily feeds on crustaceans and insects; while in saltwater areas, it feeds on molluscs and crustaceans. The favorite foods are an amphipod in freshwater, and rock clams, Atlantic razor clams, and Arctic wedge clams.
