Description: Gadwalls are medium-sized ducks characterized by a general lack of bright coloration. Males are gray-brown, with a white belly, and a black rump. In flight, a white speculum and chestnut and black portions on the wing coverts are displayed. The bill is slate-gray and the legs and feet are yellow. The male utters a short "nheck" and a low whistle. Female gadwalls are similar to males, but have a mottled brown appearance, a yellowish bill with dark spots, and a smaller white speculum. She utters a repeated "gag-ag-ag-ag-ag" higher in pitch than the mallard.
Breeding: Gadwall breed near seasonal and semi-permanent wetlands, mainly in the shortgrass, tallgrass, and mixed prairie regions of the US and Canada. Substantial numbers also breed in wetland habitats of the Great Basin. Gadwall tend to begin breeding later than most ducks. Female gadwall nest in fields and meadows, and on islands and dikes in wetlands and lay an average of 7 to 12 eggs.
Migrating and Wintering: Gadwall are distributed throughout the southern two-thirds of the USA in winter, with the greatest concentrations found in the Central and Mississippi Flyways. They are found throughout much of the intermountain west of North America, and most of Mexico, in reservoirs, farm ponds, and coastal fresh and brackish marshes. They are often found in association with American wigeon and American coots. Gadwall are a common winter visitor to Guatemala (Scott and Carbonell, 1986).
Population: The North American gadwall population remained stable through the 1970s and early 1980s, while populations of other waterfowl species generally declined. Since the late 1980s, the gadwall population has increased to record levels.
Food habits: Aquatic vegetation makes up the majority of the gadwall's diet. As a result, they are often found feeding far from the shoreline, in deeper water than most other dabbling ducks. Gadwall up-end to feed on leafy portions of pondweeds, naiad, widgeon grass, water milfoil, and algae and the seeds of pondweeds, smartweeds, bulrush, and spike rush. They also feed on aquatic invertebrates, such as crustaceans and midges.