Greater ScaupAythya marila

adult male, breeding
Jari Peltomaki/VIREO
adult female, breeding
Arthur Morris/VIREO
immature male (1st year) Tufted Duck in front
Steve Young/VIREO
adult male, nonbreeding
Steve Young/VIREO
adult male, breeding
Arthur Morris/VIREO
adult female, breeding
Rob Curtis/VIREO

Description

The more northerly of our two scaup species, the Greater is also found across northern Europe and Asia. Winter flocks on coastal bays may number in the thousands. When a flock is feeding on waters where a tide is running, the birds generally face up-current; there may be a continuous shifting as birds from the back of the flock take off and fly to the front, so that the flock stays in roughly the same position despite the down-current tidal drift of individuals.

Habitat

Lakes, rivers, salt bays, estuaries. In summer on lakes and bogs in semi-open country near northern limits of boreal forest, and out onto tundra. In winter mainly on coastal bays, lagoons, estuaries; some on lakes inland. Overlaps with Lesser Scaup at all seasons, but in winter the Greater tends to be on more open bays, more exposed situations.

Feeding Diet

mostly mollusks and plant material. Diet in winter is mainly mussels, clams, oysters, snails, and other mollusks. In summer (and perhaps in winter on fresh water) consumes plants including pondweeds, wild celery, sedges, grasses, and others; also insects and crustaceans.

Feeding Behavior

forages by diving and swimming underwater; large food items brought to surface to be eaten. Occasionally forages by dabbling or up-ending in shallow water. May feed at any time of day, or at night, with timing affected by tides in coastal regions.

Nesting

Pair formation occurs mostly in late winter and early spring. Several males may court one female. Display elements of the males include throwing the head back sharply while giving a soft call; exaggerated bowing movements, with bill tip lowered to water and then raised high; flicking wings and tail while giving soft whistled notes. Nest site usually very close to water on island, shoreline, or mats of floating vegetation. Nest is a shallow depression, lined with dead plant material and with down. Female chooses nest site and builds nest. Several nests may be close together in loose colony. Eggs: 7-9, sometimes 5-11. Olive buff. Incubation is by female only, 24-28 days. Young: female leads young to water shortly after hatching; 2 or more broods may join, tended by 1 or more females. Young feed themselves, are capable of flight 40-45 days after hatching.

Eggs

7-9, sometimes 5-11. Olive buff. Incubation is by female only, 24-28 days. Young: female leads young to water shortly after hatching; 2 or more broods may join, tended by 1 or more females. Young feed themselves, are capable of flight 40-45 days after hatching.

Young

female leads young to water shortly after hatching; 2 or more broods may join, tended by 1 or more females. Young feed themselves, are capable of flight 40-45 days after hatching.

Conservation

Populations have been declining significantly for the last few decades. The causes for these declines are not well understood, but pollution in coastal areas could be one factor.

Range

Migrates in flocks. Birds from Alaska may winter on either Pacific or Atlantic coast; banding records indicate that the same individual may go to opposite coasts in different winters, probably as a result of joining different flocks.

Listen

harsh female calls
courting group

Similar Species

adult male, breeding

Lesser Scaup

One of the most numerous and widespread diving ducks in North America, especially on inland waters. Can be very active when feeding, diving and surfacing repeatedly. In winter often seen on lakes and bays in dense flocks, numbering hundreds or even thousands, and often with no other species of ducks associated with them. The two species of scaup sometimes occur in the same places, but they tend to keep to themselves rather than mixing freely.

adult male, breeding

Ring-necked Duck

Although it mixes freely with other diving ducks on large lakes in winter, the Ring-neck is also found on small, tree-lined ponds, and associating with dabbling ducks on shallow waters. A strong and fast flier, it is able to take flight by springing up directly from the water, without the laborious take-off run of most diving ducks. Despite the name, the ring on its neck is almost never visible.

adult male, breeding

Tufted Duck

A common diving duck of the Old World, the Eurasian counterpart of our Ring-necked Duck. Tufted Ducks wander to North America from both directions, reaching the northeast from Europe and Iceland, reaching Alaska and the Pacific Coast from Asia. Although they are turning up more often, they are still considered rare everywhere except western Alaska.

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