Red-breasted Merganser

The Red-breasted Merganser is another sea duck that winters off the coast of New Hampshire and is sometimes seen inland during migration. Unlike the other wintering coastal ducks however, the Red-breasted Merganser breeds much closer to the Granite State, with records as close as Lake Champlain, northern Maine, and much of Maritime Canada. Unlike our local breeding mergansers it nests on the ground, usually partially concealed by dense vegetation, rocks, or a fallen log. In some parts of their range they nest in loose colonies on islands with gulls and terns.

While male Red-breasted Mergansers are immediately recognizable by their shaggy crests and rusty breast, the females are another matter. With gray backs, white sides, and brownish heads they look very similar to female Common Mergansers. The female Red-breasted is best told by her browner head (vs. rusty/orange in Common) and less distinct delineation between the head and neck. Another reliable identification tip is habitat. If you see a female merganser on the ocean it is almost certainly a Red-breasted. If it’s on a lake or river, especially from June to September, it is a Common.

Like other mergansers, this species eats primarily fish, the capture of which is facilitated by their serrated bill. In some areas there has been concern about the negative effects of merganser predation on fish populations, particularly related to young salmon or popular sport fish. Available data indicate that while predation obviously occurs, it is not high enough to be a sole factor behind declines in fishery stocks in areas where it has been studied.