The Red-breasted Merganser (Mergus serrator Linnaeus) can be distinguished from the common mergansers in a mixed group because of its smaller size. The red-breasted male merganser can be distinguished from the common merganser because of its tousled crest, its white collar, and its striped chest while the female is differentiated by its paler head and neck as well as its white chin and white front neck. In flight, the adult drake has the wing top marked with a white square partly crossed with two black lines. The eclipsed male looks like the female, but it keeps its alar pattern. The female displays a white square partly crossed by one black line on the internal secondaries and on the big coverts. The ducklings look like the adult female.
This species nests in forests close to water bodies and in covert coastal zones. It is abundant while migrating in the Great Lakes where a moderate group winters. It is also quite common elsewhere within the upcountry, mostly in brackish and salted waters during winter.
During its nesting period, the red-breasted merganser builds its nest on the ground. When appropriate, bushes, low tree branches, and rock holes are its shelter. The female is the only one who takes care of the incubation period that lasts 28 to 31 days and lays an average of 8 eggs. The drake leaves the nest immediately after the laying to undertake its mutation elsewhere. The precocial ducklings step in the water as soon as their shell breaks.Finally, the red-breasted duck, an aquatic duck, eats mostly fish, molluscs, crustaceans, and aquatic insects, but it sometimes eats vegetable matter like its cousins. X