Mallard & Black Duck
The ubiquitous Mallard (Anas platyrhynchos) is a familiar sight to most of us. Though it prefers shallow ponds and marshes for its habitat, it can turn up on almost any unfrozen body of water in our area at any time of the year.
The drake is easily identified as a Mallard most of the year by its bright iridescent green head, rich brown breast, white neck ring, yellow bill, and pale gray body.
The hen Mallard, though, can be confused with the American Black Duck (Anas rubripes) a declining, but still common bird. These two closely related species are nearly identical in size, structure, and voice, but, with practice, even female Mallards can be readily distinguished from Black Ducks by their plumage. The American Black Duck is found in habitats like the Mallard’s, but tends to be somewhat warier of humans, and so favors more secluded areas. Though outnumbered by Mallards at all times of the year here, Black Ducks become more common relative to the Mallard in migration seasons and in winter, when more northern breeding populations of Black Ducks migrate south.
|Both drake and hen Black Ducks and hen Mallards are mostly brown, with lighter brown on the head and neck than on the rest of the body. The main difference between them visible at a distance is the Black Duck’s darker coloration. At rest, the Black Duck appears a uniform very dark brown from the bottom of the neck to the tail. The hen Mallard is a much lighter brown in this area, and in addition has a pale whitish patch on the belly and a whitish tail.
There is also a difference in head pattern—though both species are a finely streaked light brown on the head and neck, the Black Duck’s coloration here is somewhat darker and grayer than the Mallard’s. The hen Mallard also has an unstreaked whitish throat where the Black Duck’s throat is finely streaked with grayish-brown. Bill color is another clue—with a good view, one can observe that the hen Mallard’s bill is orange and black, where the Black Duck’s bill ranges from a dusky greenish yellow to a drab olive color.
Both species have a colorful iridescent patch on the top of the secondary flight feathers called a speculum, best seen in flight, but also often partly visible at rest. The Mallard’s speculum is blue, with a thin line of white along both its top and bottom edges, where the Black Duck’s has no white, and ranges from a deep, dusky blue to purplish. Both species have white underwings, only visible in flight.
Many are surprised to learn that in the past the Mallard did not breed in the northeastern United States at all. Our Mallard population consists of the descendants of birds released by hunters and wildlife officials, and of escapes from parks and private waterfowl collections. The resounding success of the Mallard in our area is thought to have affected the native and formerly much more common Black Duck adversely, through competition for habitat and hybridization.
Hybrid Mallard X Black Ducks are seen fairly frequently, and can show almost any combination of features of the two species, an unfortunate complication for the identification guidelines given above. Fortunately, these hybrids are vastly outnumbered by typical-looking birds that can be clearly assigned to one species or the other.