American Black Duck

Identification

The American black duck weighs 720–1,640 g (1.59–3.62 lb) and measures 54–59 cm (21–23 in) in length with a 88–95 cm (35–37 in) wingspan. This species has the highest mean body mass in the genus Anas, with a sample of 376 males averaging 1.4 kg (3.1 lb) and 176 females averaging 1.1 kg (2.4 lb), although its size is typically quite similar to that of the familiar mallard. The American black duck somewhat resembles the female mallard in coloration, although the black duck's plumage is darker. Males and females are generally similar in appearance, but the male's bill is yellow while the female's is dull green with dark marks on the upper mandible, which is occasionally flecked with black. The head is brown, but is slightly lighter in tone than the darker brown body. The cheeks and throat are streaked brown, with a dark streak going through the crown and dark eye. The speculum feathers are iridescent violet-blue with predominantly black margins. The fleshy orange feet of the duck have dark webbing.<p>Both male and female American black ducks produce similar calls to their close relative, the mallard, with the female producing a loud sequence of quacks which falls in pitch.<p>In flight, the white lining of the underwings can be seen in contrast to the blackish underbody and upperside. The purple speculum lacks white bands at the front and rear, and rarely has a white trailing edge. A dark crescent is visible on the median underwing primary coverts.<p>Juveniles resemble adult females, but have broken narrow pale edges of underpart feathers, which give a slightly streaked rather than scalloped appearance, and the overall appearance is browner rather than uniformly blackish. Juvenile males have brownish-orange feet while juvenile females have brownish feet and a dusky greyish-green bill.

Taxonomy

American ornithologist William Brewster described the American black duck as Anas obscura rubripes, for "red-legged black duck", in his landmark article "An undescribed form of the black duck (Anas obscura)," in The Auk in 1902, to distinguish between the two kinds of black ducks found in New England. One of them was described as being comparatively small, with brownish legs and an olivaceous or dusky bill, and the other as being comparatively larger, with a lighter skin tone, bright red legs and a clear yellow bill. The larger of the two was described as Anas obscura by the German naturalist Johann Friedrich Gmelin in 1789 in the 13th edition of the Systema Naturae, Part 2, and he based it on the "Dusky Duck" of Welsh naturalist Thomas Pennant. The current scientific name, Anas rubripes, is derived from Latin, with Anas meaning "duck" and rubripes coming from ruber, "red", and pes, "foot".<p>Pennant, in Arctic Zoology, Volume 2, described this duck as coming "from the province of New York" and having "a long and narrow dusky bill, tinged with blue: chin white: neck pale brown, streaked downwards with dusky lines." In a typical obscura, characteristics such as greenish black, olive green or dusky olive bill; olivaceous brown legs with at most one reddish tinge; the nape and pileum nearly uniformly dark; spotless chin and throat; fine linear and dusky markings on the neck and sides of the head, rather than blackish, do not vary with age or season.

Scientific name

Anas rubripes

Authority

Brewster, 1902

Order

Anseriformes

Family

Anatidae

Genus

Anas

Range and habitat

The American black duck is endemic to eastern North America. In Canada, the range extends from northeastern Saskatchewan to Newfoundland and Labrador. In the United States, it is found in northern Illinois, Michigan, New Jersey, Ohio, Connecticut, Vermont, South Dakota, central West Virginia, Maine and on the Atlantic coast to North Carolina.<p>The American black duck is a habitat generalist as it is associated with tidal marshes and present throughout the year in salt marshes from the Gulf of Maine to coastal Virginia. It usually prefers freshwater and coastal wetlands throughout northeastern America, including brackish marshes, estuaries and edges of backwater ponds and rivers lined by speckled alder. It also inhabits beaver ponds, shallow lakes with sedges and reeds, bogs in open boreal and mixed hardwood forests, as well as forested swamps. Populations in Vermont have also been found in glacial kettle ponds surrounded by bog mats. During winter, the American black duck mostly inhabits brackish marshes bordering bays, agricultural marshes, flooded timber, agricultural fields, estuaries and riverine areas. Ducks usually take shelter from hunting and other disturbances by moving to brackish and fresh impoundments on conservation land.

Breeding range

NA : e Canada and ne USA

Non-breeding range

e USA

Migration

Complete migrants

Behavior

Migration pattern: Complete migrants.

Conservation

Population trend: declining.

Population trend

declining