From SongbirdReMixWiki

Jump to: navigation, search


Common Name: Gadwall
Scientific Name: Anas strepera

Size: 18-22 inches (46-56 cm); Wingspan: 31-35 inches (78-90 cm)

Habitat: Worldwide; breeds in the northern areas of Europe and Asia, and central North America. In North America, its breeding range lies along the Saint Lawrence River, through the Great Lakes, Alberta, Saskatchewan, the Dakotas, south to Kansas, west to California, and along coastal Pacific Canada and southern coastal Alaska. The range of this bird appears to be expanding into eastern North America. This dabbling duck is strongly migratory, and winters farther south than its breeding range, from coastal Alaska, south into Central America, and east into Idaho, Kansas, Ohio, Virginia, and then south all the way into Central America.

Gadwall breed mainly in prairie potholes—small ponds scattered throughout the Great Plains and Canadian prairies. Some also breed on tundra, deltas, and wetlands in boreal forests of the far north. In developed areas with few natural ponds, Gadwall may use stock ponds. They choose well-vegetated wetlands with plenty of emergent plants to feed among and take cover in. Equally important for breeding are adjacent uplands with vegetation to conceal nests and for ducklings to hide in. On migration and in winter, look for Gadwall in fresh and salt water marshes and well-vegetated reservoirs, beaver ponds, farm ponds, and streams.

Status: Least Concern. Global population: 3,000,000 adult individuals. The Gadwall is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

Diet: Submerged aquatic vegetation such as algae, grasses, rushes, sedges, pondweed, Wigeon grass, and water milfoil, including leaves, stems, roots, and seeds. They also eat snails, midges, water beetles, and other invertebrates. During the breeding season, animal matter can account for nearly 50 percent of an adult Gadwall’s diet, but this proportion drops to only about 5 percent animal matter during winter.

Gadwall rest fairly high in the water and they tip forward to graze on submerged plants that they can reach with their outstretched necks. They rarely dive.

Nesting: The male is slightly larger than the female. The breeding male is patterned grey, with a black rear end, light chestnut wings, and a brilliant white speculum. In non-breeding (eclipse) plumage, the drake looks more like the female, but retains the male wing pattern, and is usually greyer above and has less orange on the bill.

The female is light brown, with plumage much like a female Mallard. It can be distinguished from that species by the dark orange-edged bill, smaller size, the white speculum, and white belly. Both sexes go through two molts annually, following a juvenile molt. Juveniles look similar to the female.

Gadwall are seasonally monogamous and will pair up during fall migration. Once they return to their breeding grounds, they select their nest site while flying low over dry, grassy areas. The female makes a closer inspection on foot while the male stands guard near her. They typically choose dense brush or grasses at least a foot tall, usually within 200 yards of open water. They prefer nesting on islands, when possible, for greater safety from predators. In heavily cultivated areas, untilled land for nest sites can be a scarce resource.

The female scrapes out a hollow, then settles into the nest and reaches out to grab twigs and leaves with her bill. She sets these against herself to form the base of a nest cup, then plucks her own down feathers to make an insulating lining. The finished nest is about a foot across with a cup 3 inches deep. It takes 5–7 days to go from looking for a nest site to having a finished nest ready for egg laying. The female Gadwall produces an egg a day, laying 7–12-egg clutches.

Cool Facts: Gadwall will sometimes steal food from American Coots and from other ducks.

Gadwalls have a set of movements that communicate pair bonds, levels of aggression, and degrees of interest among potential mates. For example, Gadwall may warn another bird to stay away by lifting its chin or opening its bill. A male may seek a female’s attention by ruffling his head feathers, drawing the head close to the body, and then rearing up out of the water and pushing his head forward. Further courtship displays include the male arching his head over his back and then jerking forward while raising his tail and wing coverts; pushing his bill underwater and then quickly tossing water into the air while whistling; and rearing up while raking his bill through the water and whistling. A female may show her interest by arching her head and neck and repeatedly moving it forward and then to the side away from the male. As the pair bond strengthens, the two birds face each other and raise and lower their heads, chins up; or turn their head and place the bill behind the wing, as if preening.

The oldest known Gadwall was 19 ½ years old. It was banded in Saskatchewan in 1962 and shot during hunting season in Louisiana in 1981.

Found in Songbird Remix Waterfowl Volume I: Dabbling Ducks

Personal tools