Porrón bastardo

Identification

The greater scaup is a mid-sized diving duck, larger than its closely related cousins the lesser scaup and tufted duck. Males are noticeably striking: they sport a dark head with a green to purple iridescent gloss (depending on the angle of light), a black breast, and bright white underside and flanks. Their light blue-grey bill and yellow eyes are distinctive features. Females are altogether more subdued, presenting a mostly brown body and head with a characteristic white patch on the face and a duller blue bill. Both sexes display a strong white stripe on the wing—a key identifying feature.

Males average slightly larger than females but with considerable overlap in size. In the field, distinguishing greater scaups from the similar lesser scaup can be challenging, but the greater scaup's more rounded head, more extensive white wing stripe, and larger, wider bill with a slightly larger black nail at the tip are helpful clues. North American birds tend to have a higher forehead and reduced white on the wings compared to their European counterparts.

Range & habitat

The greater scaup boasts a circumpolar distribution, breeding within the Arctic Circle across both the Old World and North America. Summer breeding grounds span from Iceland eastward across Scandinavia, northern Russia, and Siberia, as well as Alaska and northern Canada. Though mostly migratory, small populations remain year-round in Iceland and the Aleutian Islands. During winter, birds migrate south to coastal regions of Europe, eastern Asia, and North America.

For breeding, greater scaups nest near water, typically on islands in northern lakes or on floating mats of vegetation. This preference for remote northern wetlands and their subsequent migration to coastal wintering grounds makes them birds of both freshwater and marine environments.

Behaviour & diet

Greater scaups are highly gregarious birds, often forming enormous groups called "rafts" that can number in the thousands. As diving ducks, they forage by diving underwater to depths of 0.5 to 6 metres, occasionally reaching 10 metres in search of food. Their diet consists primarily of aquatic molluscs, plants, and insects. They breed at age two, and females lay clutches of six to nine olive-buff-coloured eggs that hatch within 24 to 28 days. The downy ducklings are precocial and can follow their mother to feed immediately after hatching.

Drakes engage in complex courtship displays that occur during the return migration to breeding grounds, ultimately resulting in the formation of monogamous pairs. Beyond natural predation from owls, skunks, raccoons, foxes, and coyotes, the species faces threats from human development. Populations have declined since the 1980s, though the species remains listed as of least concern by the IUCN.

Best time & places to see it

Winter is the optimal season for observing greater scaups, when they congregate in large numbers along the coasts of Europe, eastern Asia, and North America. The coastal habitats they favour during this period make them more accessible to observers than during their dispersed breeding season in remote Arctic regions. Their habit of forming vast rafts means that when you do locate them, sightings can be spectacular and rewarding.

Photography tips

The greater scaup's striking plumage makes it a rewarding subject, particularly males with their glossy dark heads and crisp white underparts. Photograph in good light to capture the subtle green to purple iridescence of the male's head. Coastal winter locations offer opportunities to photograph large flocks, while the white wing stripe is best revealed when birds are in flight or stretching their wings. The contrast between male and female plumage provides excellent compositional opportunities for comparison shots. Patient observation of rafts may reward you with behavioural sequences including diving, courtship displays, or wing-flapping displays.