The Greater Scaup is a diving duck that can be seen around Puget Sound in winter. Look for it making an occasional appearance along the Edmonds waterfront. Mostly it flies by in small- to medium-sized flocks, but every so often it can be seen swimming either alone or with other duck species. It is a circumpolar species during its breeding season. It winters along most coastal waters in the Lower 48, but can also be found on larger bodies of freshwater.
Diet is mostly comprised of mollusks and plant material. In winter the Greater Scaup eats mussels, oysters, claims, snails, and other mollusks. In summer it eats mostly plants, including pondweeds, sedges, grasses, and wild celery. Its summer diet also includes some insects and crustaceans. It forages by diving and swimming under water. It brings large food items to the surface before eating. When in shallow water, the Greater Scaup occasionally will forage by dabbling or upending. It feeds at any time of day or night.
Pair formation takes place in late winter and early spring. Male courtship displays include giving a soft call while throwing its head back sharply, bowing movements with the bill tip lowered to the water and then raised high, and flicking the wings and tail whistling soft notes.
Breeding grounds are on lakes and bogs in semi-open country near the northern limits of boreal forests, as well as on tundra. The nest is a shallow depression that is lined with dead plant material and down. It is usually close to water on an island, shoreline, or mat of floating vegetation. There may be a loose colony of several nests.
The female incubates her seven to nine eggs for 24-28 days. The female leads her young to water shortly after hatching. The young feed themselves and take their first flight at 40-45 days of age. Once incubation begins, the male leaves to undergo molt on a relatively large, isolated lake. The male looks for a shallow lake with abundant food and suitable cover.
The oldest recorded Greater Scaup was male, and at least 20 years and five months of age when found in Michigan in 2007. He had been banded in New York in 1998.
The conservation status of species can be somewhat puzzling. The IUCN status of the Greater Scaup is least concern. However, the U.S. Fish & Wildlife Service notes that this species has declined since the 1950s. And the 2014 State of the Birds Report identifies Greater Scaup as a common bird that is in steep decline. Accurate population counts can be difficult because it looks so similar to the Lesser Scaup and the two share some habitats.
— By Carol Riddell
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.