Description: The red-breasted merganser's small head, slender neck and tapered body give it a streamlined appearance in the air. The male shows a striking, wide band of white that extends almost the full length of the body and a dark band across its chest. The dark green head appears black at a distance and is tufted at the back, unlike the smooth head of the common merganser. Male red-breasted mergansers have deep red eyes and feet. The back is black, the rump gray-brown with fine black bars. Wavy lines of black bar the white sides and flanks, creating a distinct contrast with the white belly.
Large white patches, similar to those of the common merganser and goldeneye, span the inner wing of the male, separated by two narrow black bars. The white patch formed by the white middle coverts on the shoulder is margined at the wing edge by the dusky feathers of the lesser coverts. One black bar is formed by the black base of the white greater coverts and the other by the black base of the white secondaries.
The female red-breasted merganser has a dusky gray back enlivened occasionally by a small white patch in front of the tail. Except for their smaller size, female red-breasted mergansers greatly resemble common mergansers. They have cinnamon-brown heads and lightly mottled gray backs and sides. The two species can be distinguished by noting that the white throat of the red-breasted merganser merge imperceptibly with the brown head, whereas the common merganser's throat is more sharply defined against its reddish-brown head. Female red-breasted mergansers also have a slight protrusion of feathers at the back of their head. The female also has lighter red eyes and feet than the male. They have ash-gray shoulders and a small white patch on the speculum formed by the inner white secondaries, with a black base. The primaries and their coverts are dusky brown.
Both males and females have long, narrow bills with serrated edges, which are bright red in the male and duller in the female.
Breeding: The breeding range of the red-breasted merganser generally extends farther north and not as far south as the common merganser. The principal region of overlap is in southeastern and southern Canada. Although red-breasted mergansers breed over most of Alaska, including the Aleutian Islands, they are most abundant on areas adjacent to the Bering Sea. They nest east through the tundra of Labrador and northern Quebec to central Baffin Island. They also lay sole claim to the tundra along the southern and west coasts of Hudson Bay, north to Eskimo Point and Coronation Gulf, then south through the tundra and most of the open boreal forests of the Northwest and Yukon territories.
Unlike common and hooded mergansers, which usually nest in tree cavities, red-breasted mergansers nest on the ground in highly diversified sites. They have been found nesting in marshes, on rocky islets, on vegetated islands in large lakes, in bank recesses and under piles of driftwood. Hens lay eggs in the nests of other ducks and vice versa. North American nests contain an average of 5-11 eggs.
Migrating and Wintering: The bulk of the red-breasted merganser populations that breed in the interior of North America migrate toward the Atlantic or Pacific coasts before reaching their wintering grounds, though a small number migrate into the Great Lakes. Some remain there for winter, but many continue farther south to wintering grounds along the Gulf Coast and probably along the mid-Atlantic coast. A few thousand have been known to fly south from central Canada across the Great Plains to winter along the Texas coast. Red-breasted mergansers typically migrate in small flocks of 5 to 15, with coastal flights occurring during the day and inland flights at night.
Food habits: Red-breasted mergansers feed on fish (herring, fry, minnows), fish eggs and occasionally shrimp and crabs. Usually they dive for food, hunting on lakes and rivers, in coastal bays and at sea.