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". 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. Description The American black duck weighs and measures in length with a wingspan. This species has the highest mean body mass in the genus Anas, with a sample of 376 males averaging and 176 females averaging , 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 , 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. 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. In flight, the white lining of the underwings can be seen in contrast to