The American Black Duck is the only duck in Québec in which both sexes have almost identical plumage: sooty brown on the body and crown and a lighter brown on the neck and rest of the head, with a dark stripe through the eye. In flight, the flashing white wing linings contrast sharply with the rest of its dark wings and body. The speculum (wing patch) is an iridescent purplish-blue. During the breeding season, the adult male has a yellow bill and often bright red feet, while the adult female has an olive green bill and olive-coloured feet.
Wintering mainly along the Atlantic coast and Mississippi Valley, pairs return to their breeding grounds in Québec between late March and early May. The American Black Duck frequents a variety of wetland habitats, including small lakes, ponds, peatlands, swamps, rivers and streams associated with mixed or coniferous forest. However, pairs may also be seen nesting in deciduous forests or fields near water.
The hen most often builds her nest on the ground. Usually camouflaged by tall grass, hidden underneath shrubs or the low branches of a conifer, nests are generally close to water, although they may occasionally be over a kilometre away. A typical clutch size contains 6 to 12 eggs, which are laid at an interval of one a day and incubated for an average of 28 days. At the beginning of incubation, the drake, who was busy defending the territory, goes off to moult. Shortly after the eggs hatch, the hen leads her offspring to a brood-rearing area that has abundant food and adequate escape cover. The hen continues to tend her brood until they fledge, 60 days or so after hatching (late July). She then leaves her brood to go off to moult on her own in an area where she is safe from predators.
Near the end of summer, Black Ducks congregate in small flocks to prepare for fall migration along the province´s larger bodies of water. They are hunted from mid-September to December. Banding recoveries are particularly useful for documenting hunting dispersal and estimating sport harvest rates.
The species’ diet varies widely depending on the habitat and may consist mainly of plant food (the seeds and other parts of aquatic plants, wild berries, cereal grains, etc.) or animal prey (small molluscs, amphipods, etc.). Ducklings feed mainly on insect larvae and other invertebrates, but, consume a greater proportion of seeds of aquatic plants as they grow older.