The Greater Scaup is a large diving duck that breeds in Arctic tundra wetlands and coastal regions of North America and Eurasia. It spends much of the year on large lakes, estuaries, bays, and coastal marine waters, where it feeds by diving for aquatic prey. Its diet consists mainly of mollusks, crustaceans, aquatic insects, and other invertebrates, although it also eats some aquatic vegetation. Greater Scaup typically occurs in flocks, especially during migration and winter, when thousands may gather on productive coastal waters. In inland North America, it is generally less common than the closely related Lesser Scaup.
Habitat
The Greater Scaup inhabits Arctic tundra wetlands, coastal ponds, and shallow lakes during the breeding season. During migration and winter it is most often found on large lakes, reservoirs, estuaries, bays, and coastal marine waters, especially areas with abundant mollusks and other aquatic invertebrates.
Diet
The Greater Scaup feeds primarily on mollusks, clams, mussels, snails, crustaceans, and aquatic insects obtained by diving underwater. It also eats small fish, aquatic plants, and seeds, particularly during migration and on inland waters.
Behavior
A diving duck, primarily foraging by diving from the water's surface and swimming underwater for food items. They will also sometimes act like dabbling ducks, swimming on the water's surface and grabbing food items from the surface or by dipping the head below the surface.
Breeding
Non-breeder in South Dakota. In range, the Greater Scaup nests on the ground in Arctic tundra near ponds, lakes, marshes, and coastal wetlands. The female builds a shallow bowl-shaped nest lined with grasses, sedges, and soft down feathers, usually hidden among low vegetation. Typical clutches contain 6–11 eggs, and the female alone incubates the eggs and cares for the ducklings after hatching.
Song
The Greater Scaup is generally quiet, but males give soft whistled notes and low purring calls during courtship displays. Females produce rough growls, croaks, and short quacking sounds, especially when defending nests or communicating with ducklings.
Migration
The Greater Scaup breeds in Arctic regions of North America and Eurasia and migrates south in fall to winter along both Atlantic and Pacific coasts, the Great Lakes, and other large open-water habitats. Most winter on coastal bays, estuaries, and marine waters, although some occur on large inland lakes and reservoirs. During migration, the species may form large flocks, often associating with other diving ducks such as the Lesser Scaup.
Interactive eBird Map
Click here to access an interactive eBird map of Greater Scaup sightings
Similar Species
Lesser Scaup, Ring-necked Duck. The Greater Scaup is larger and bulkier than the Lesser Scaup, with a rounder head profile that lacks the rear peak often shown by Lesser Scaup. In flight, Greater Scaup displays a broad white wing stripe extending well into the outer primaries, whereas the white stripe on Lesser Scaup is usually more restricted. Compared to the Ring-necked Duck, Greater Scaup has a rounder head, a broader bluish bill without the bold white rings, and lacks the Ring-necked Duck’s peaked head shape and contrasting white markings on the bill and flanks.
Conservation Status
The Greater Scaup is generally considered a species of low conservation concern, although populations have shown long-term declines in parts of North America. Potential threats include habitat degradation on Arctic breeding grounds, pollution, changes in marine food resources, and disturbance or contamination of important migration and wintering habitats. The IUCN considers the Greater Scaup to be a species of "Least Concern".
Further Information
- eBird - Greater Scaup
- Audubon Field Guide - Greater Scaup
- Cornell Lab of Ornithology - All About Birds: Greater Scaup
Photo Information
May 1st, 2009 - Lake Thompson , South Dakota - Terry Sohl
