Breeding male
This plumage is acquired in the fall (September-November) and is held until the following summer (June-July). The lower back, scapulars, rump, and uppertail coverts are black, with a large, rounded white spot on each side of the rump; the two longest scapulars are twisted at the tips and held erect, thus appearing as two short, triangular points, or ‘sails’, on the back. The upperwings are primarily black, with a large, oval-shaped or rectangular white patch across the upperwing coverts. The short, pointed tail is black. The belly, sides, flanks, and undertail coverts are black and are sharply demarcated from the variably (often strongly) pink-washed or cinnamon-washed white breast. The underwing coverts are white, contrasting with the dusky-black underside of the flight feathers. The neck and upper back are white, sharply demarcated from the black upperparts. The crown and nape are soft, pale blue-grey, and the feathers of the nape are long and create a puffed-out shape on the back of the head. There is a narrow dusky or blackish line extending downwards from the eye, separated from the blue-grey nape by a narrow white line that also extends up and over the eye. The chin, throat, and foreneck ate white and the cheeks are washed with pale green (darkest below the eye). The bill is bright red with a whitish tip, expanding into a large, square, black-rimmed orange frontal shield at the base that extends across the forehead. The iris is dark and the legs and feet are yellow.
Non-breeding (Eclipse) male
This plumage is acquired in the summer (July) and is held only briefly before being lost in the fall (September-November). Eclipse males are overall dark blackish-brown, with pale whitish and pale brown mottling on the breast and sometimes on the back. The upperwing coverts have large, sharply-defined white patches that are similar to those found in the breeding male. Bare part colouration, including that of the bill and frontal shield, is similar to the breeding male.
Adult female
The back, scapulars, lesser and median upperwing coverts, rump, and uppertail coverts are mottled with dark brown, buff, and rufous-buff, with the blackish subterminal bands and pale fringes on the feathers giving the upperparts a somewhat scaled appearance; the two longest scapulars form short points, or ‘sails’, on the back similar to the adult male. The flight feathers, primaries, and primary coverts are dark grey-brown, with narrow buffy or whitish tips to the secondaries and greater secondary coverts forming two pale secondary bars on the spread wing. The short, pointed tail is buffy-brown. The underparts (including the breast) are wholly buff (sometimes tinged with rufous) and are extensively barred and scaled with blackish-brown, chevron-shaped bars. The underwings are dark brownish-grey (underside of flight feathers grey) with extensive white on the axillaries and underwing coverts. The head and neck are buffy or rufous-buff, with fine dark streaks on the forehead, crown, nape, sides of the face, and sides of the neck; the area around the eye is usually clear buffy, extending back into a narrow buff line along the sides of the nape. The iris is dark, the bill is dark grey to olive-grey and lacks a frontal shield, and the legs and feet are greenish-grey to dusky.
Second-winter immature male
This plumage is acquired in the fall of the second year and is held throughout the following winter, spring, and summer (lost in mid-summer). It is very similar to the plumage of the adult male, but often has some dingy mottling on the face and breast (at least when fresh) and has less extensive and more irregularly-shaped white patches on the upperwing coverts.
First-summer immature male
This plumage is held from spring (~April) to summer (~July) of the second year. It is a highly variable plumage and is difficult to characterize. Individuals that have molted only the head feathers resemble advanced first-winter plumage but show a mottled greyish-brown crown and nape contrasting with the somewhat browner cheeks and greyish-buff throat and chin. As well, such individuals tend to show a variable semi-collar of mixed black and white feathers on the upper breast. More advanced individuals that have molted most of the body and head feathers tend to have a greyer crown and nape, almost pure white throat, breast, and collar, and a moderately distinct black “V” on the chin. The presence of a white collar in this age class is a highly diagnostic field mark. As well, such individuals have a variable (often extensive) amount of fresh black feathering on the back, scapulars, rump, and sides and show fairly bold, oval-shaped white patches on the sides of the rump. Particularly advanced individuals in first-alternate plumage even begin to acquire a greenish wash to the whitish cheeks, as is shown in adult breeding plumage.
First-winter immature male
This plumage is acquired in the fall of the first year following a prolonged molt and is held throughout the following winter. Immature males in first-winter plumage can be easily aged by the distinct, but variable, white breast that contrasts noticeably with the blackish body and dark head, especially in late winter or on particularly advanced individuals. The head is also variably speckled and mottled with brown, including a buffy line from the eye to the nape (similar to that found in adult females). Birds in this plumage often begin to exhibit the whitish patches on the sides of the rump that are so prominent in adult males, although these will be irregular and variable at this age. The blackish flanks contrast with the retained brownish feathers on the belly and under tail coverts, and some individuals even begin to show a suggestion of the unique modified, sail-like scapulars that are present in adult males. The olive-grey bill gradually reddens and the yellowish-orange frontal shield enlarges and brightens during the late fall and winter, although the size of the frontal shield is still much reduced from what is shown in adult males. Although the body and head feathers have been molted, the brown juvenal wing feathers are retained and birds in their first winter will still exhibit uniformly brown wings when in flight.
Measurements
Total Length: 55-56 cm
Mass: 1,670-1,850 g
Source: Sibley (2000); Suydam (2000); Fenneman and Toochin (2006)
