Illustration by Cynthia J. House
Probably the most widely recognized and widespread duck in North America, the mallard forms massive, noisy flocks in large marshes and agricultural fields; mallards also make use of almost any body of water, from a roadside puddle to the Great Lakes. Polytypic. (2 ssp. in North America, nominate platyrhynchos and diazi). Length 23"(58 cm).
Identification Mallards are large dabbling ducks with heavy bodies and large, rounded heads that transition smoothly into long bills. Both sexes have bright blue speculums with bold white borders. The central uppertail coverts of the males are curled upwards; a characteristic frequently passed on to hybrid offspring. Male: distinctive, with bright yellow bill and metallic green head bordered by a white neck ring. Breast is deep chestnut, flanks finely vermiculated pale gray, and rump black with white outer tail feathers. The tertials are very unusually shaped, extremely broad at the base, tapering to a point. Female: nondescript medium brown overall, paler tan face with a streaked, brown crown, indistinct brown eye line, and orange bill with a black saddle. The belly is unmarked and buffy, paler than the body, and the outer tail feathers are whitish. Eclipse male: like female but the bill remains bright yellow and the crown and breast are darker than female. Flight: wingbeats steady and shallow, slower than other ducks, and profile resembles a miniature goose, with wings set near the rear of the bulky body, neck extended straight forward, and a short rounded tail.
Geographic Variation Two subspecies in North America, nominate platyrhynchos and the southwestern subspecies diazi, Mexican duck, which is found in pockets along the Rio Grande River in Texas, New Mexico, and southeastern Arizona. It is 10 percent smaller than platyrhynchos, and the sexes are similar, lacking the distinctive plumage of male northern mallards. Its plumage is darker than female northern mallards, and it has an all brown tail. The white borders to the speculum are narrower than on platyrhynchos but still distinct and obvious. Most diazi mallards found in the Southwest have interbred with nominate platyrhynchos. Mexican duck resembles mottled duck, but has a grayer more distinctly patterned face, streaked throat, and stronger white borders to the speculum.
Similar Species Female paler than mottled (especially western subspecies) and black duck, bill brighter orange, tail and rump paler, with distinct white borders to the blue speculum. From the smaller female gadwall by rounded head shape, lacking a distinct forehead, larger, deeper based bill, iridescent speculum with white borders. Much larger than female teal with a larger, extensively orange bill.
Voice Female gives series of loud, descending quacks for which mallard is known. Male less vocal; shorter, soft quack is often drowned out by the calls of the females.
Status and Distribution Abundant and widespread across Northern Hemisphere. Breeding: any place that has both water and cover. Typically nests on the ground in thick grass or shrubs, but also may build nests in hollow trees, on top of duck blinds, or use an old nest of another bird. Migration: driven by the availability of open water. In the spring it is the earliest migrant, along with northern pintail, appearing north of its winter range as soon as there is open water. Begins in early February; peaks in the Midwest and Great Lakes region in late March; northernmost breeders arrive in Alaska in early May. In the fall it is among the last to leave the north, retreating only as water freezes. Some begin moving south in September, however most northern breeders do not move south until October; peak numbers arrive in the Great Lakes and across the northern plains in early November. Winter: spends the winter in a variety of habitats, mostly shallow freshwater. Often very mobile in the winter; moving farther north during warmer periods, then driven back south by cold fronts.
Population The most abundant duck in North America, population more or less stable.
—From the National Geographic book Complete Birds of North America, 2006
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