Mottled ducks are brown and are not easily distinguished from American black ducks (Anas rubripes). They have an iridescent blue speculum and buffy plumage, which makes them appear lighter than other species. They lack a few features that other ducks have such as white anterior edges on the speculum. These ducks appear to be uniformly dark from a distance. Mottled ducks are sexually dimorphic. The bills of males are bright yellow, but are drab colored in females. The females are grayer whereas the males are very brown in color. The tails of the males have a faint pattern but the tails of the females are patternless. Both sexes have blackish-brown upper sides and undersides. Both also have a smoke-gray U-shaped stripe on their undersides. They weigh from 810 to 1330 g and are 50 to 61 cm long with wingspans from 243 to 270 cm. Males tend to be larger than females.
Range mass: 810 to 1330 g.
Average mass: 1043 g.
Range length: 50 to 61 cm.
Average length: 55 cm.
Range wingspan: 243 to 270 mm.
Average wingspan: 259 mm.
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful
- The American Ornithologists Union, 1992. Handbook of Birds of the World. Barcelona: Lynx Editions.