Red-breasted Merganser, Mergus serrator
Note the serrated bill, which give this species its scientific name, and which mergansers use like teeth to catch fish while diving. The similar Common Merganser is distinguished by a preference for fresh-water lakes and streams, where the Red-breasted favors shallow salt water. Red-breasted are smaller, and have a loose shaggy crest where the Common's head is smoother. The female Common has a white patch between the rufous head and the gray underparts, where the Red-breasted, above and further down the page, has blended gray-brown. The male Common in breeding plumage has pure white breast and underparts, where the Red-breasted, see the two below, has a white ring above brown or rufous breast; both have a green head, with red (Red-breasted) or dark eyes.
Both Red-breasted and Common Mergansers have a large patch of white secondaries and coverts which is conspicuous with wings raised, above, or in flight, further down the page.
Above, a Red-breasted Merganser swimming in the breakers just offshore on the Gulf Coast of Florida.
Above and below, two female or immature Red-breasted Mergansers, in Moss Landing Harbor on the shore of Monterey Bay, photographed in midwinter.
Flying pair, photographed in Teller, Alaska, an Inupiat village northwest of Nome, and the farthest north I've ever been, 89 miles south of the Arctic Circle.