The familiar Gadwall (Mareca strepera), a widespread dabbing duck, is a common spring and fall migrant in Wisconsin. Formerly placed in the genus Anas, recent phylogenetic studies led to reassignment to the genus Mareca, which now also includes the American Wigeon, its closest North American relative. The Gadwall’s breeding range is historically centered west of Wisconsin in the northern prairies of the United States and Canada, but in the twentieth century its range changed more than that of any other North American duck. The species now breeds locally in many parts of eastern North America, including Wisconsin, where favored habitats include marshes and islands in the southeast and the prairie pothole region in the northwestern counties. Gadwalls are also occasional winter residents in extreme southeastern Wisconsin.

Male Gadwall in breeding plumage. Note the steep forehead, black bill, black rump and undertail coverts, and the chestnut-edged scapulars (photo by Gary Shackelford).

Immature male Gadwall. Although the bill has some orange coloration, the vermiculated black and white breast feathers, the grayish flank, and partially developed black rump and undertail coverts indicate that this is a male (photo by Gary Shackelford).

Male Gadwall in flight. Note the white speculum and the small patches of chestnut and black on the inner median and lesser wing coverts (photo by Gary Shackelford).

Gadwalls are medium-sized, stocky ducks with a slender bill and a steep forehead. They have a subdued color pattern that is mostly grayish in males and brownish in females. Males in breeding plumage have a black rump and undertail coverts, a white speculum (most visible when the bird is in flight), and a black bill—a combination of features that easily distinguishes them from all other North American duck species. Female Gadwalls superficially resemble the female Mallard and some other female dabbing ducks, but they are distinguished from these species by their white speculum (smaller than in the male) and their distinctive orange bill with a dark longitudinal midsection. Males have patches of black and bright chestnut on some of their inner median and lesser wing coverts; in females there is little if any chestnut on the inner wing coverts. In contrast to the female Gadwall, the female Mallard has an orange bill with blackish blotches focused on the midsection and a brown belly (white in the female Gadwall).

Female Gadwall feeding on the surface of a pond. Note the overall brownish color, the light gray tertials, a thin portion of the white speculum, the orange bill with a dark median stripe, and the lack of black rump and undertail coverts (photo by Gary Shackelford).

An adult female Mallard for comparison. Note the brown belly and the saddle-shaped dark patch on the orange bill (photo by Gary Shackelford).

At Fair Meadows Sanctuary, I have logged January or February sightings in 14 years since 2000. That includes the current one, and I have taken advantage of their frequent presence at a nearby pond with a patch of open water to observe and photograph small groups at relatively close range while concealed by camouflage cover. The bulk of their time has been spent either feeding on aquatic vegetation just below the surface or resting on the nearby frozen surface of the pond. Most of the birds have been males, both adults and immatures. The few females were accompanied by males in breeding plumage. More than 95 percent of female Gadwalls are known to form pair bonds by November, so most of the unpaired males were likely yearlings.

Written by Gary Shackelford, Fair Meadows Sanctuary resident manager
Cover image by Gary Shackelford. A male Gadwall on pond ice in winter.