Breeding birds: 1-2 pairs
UK wintering: 5,200 birds
Family: Ducks, geese & swans
Adult male scaups in breeding plumage have black upper mantle, rump, and uppertail coverts. The lower mantle, back, and scapulars have black and white vermiculations which appear grey from a distance. The belly and sides of the body are white with grey vermiculations.
The upperwing coverts are dark brown with white speckles and there is a broad white wingbar over the primaries and secondaries. The underwing is white with a dark edge.
The head and neck are black with a green or purple iridescence. They have a broad pale blue bill with a small black nail. The eyes are golden yellow, and the legs and webbed feet are dark slate-grey.
Out of breeding plumage, male scaups look similar but the black parts are browner, and there are brown streaks on the side of the body. The bill is duller and it sometimes has a white base.
Female scaups have dull brown plumage with white vermiculations on the mantle, scapulars, and flanks. There are white patches around the base of the bill. She has yellow eyes which become paler in the summer, the bill is dull blue, and the legs and feet vary from dull green to dark slate-grey.
Juveniles resemble the female but are duller and paler, and lack the white patches on the face.
Scaups breed from May to early June. They nest in solitary pairs or loose groups, sometimes alongside gulls. The female builds the nest which is a depression in the ground, hidden in dense vegetation sometimes above shallow water, and lined with grass and down.
Scaups lay 5-11 olive-brown eggs which are incubated by the female alone for 24-28 days. Chicks are covered in down with chestnut-brown upperparts and yellow underparts. They leave the nest soon after hatching and follow the female to water where they are able to feed themselves. They fledge 40-45 days later.
Sometimes 2 or 3 scaups will share the same nest producing large clutches of up to 15 eggs.
Scaups have a varied diet and feed on molluscs, insects, crustaceans, worms, small fish, and aquatic plants. In winter it eats mainly mussels.
Scaups hunt their prey by diving and will either swallow it underwater or bring larger items to the surface for consumption. It will sometimes forage in shallow water by dabbling.
Scaups arrive in the UK for winter in September and leave the next April. They can be found all around the coast and in estuaries. Some come inland where they can be seen in flocks with pochards and tufted ducks.
Older female scaups may sometimes develop plumage similar to that of breeding males. She will, however, still show the distinctive white face patch.
