The gadwall (Mareca strepera) is a common and widespread dabbling duck in the family Anatidae.

Taxonomy

The gadwall was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. There are two subspecies: The etymology of the word gadwall is not known, but the name has been in use since 1666. The male is slightly larger than the female, weighing on average against her . 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.

Behaviour

thumb|Female and male dabbling, [[Hyde Park, London]]

The gadwall is a bird of open wetlands, such as prairie or steppe lakes, wet grassland or marshes with dense fringing vegetation, and usually feeds by dabbling for plant food with head submerged. They can also dive underwater for food, more proficiently than other dabbling ducks, and may also steal food from diving birds such as coots. It nests on the ground, often some distance from water. It is not as gregarious as some dabbling ducks outside the breeding season and tends to form only small flocks.

Gadwalls are monogamous and may start breeding after their first year. Pair formation begins during fall migration or on breeding grounds, but has also been reported to occur in August when males are still in eclipse plumage. Gadwalls are generally quiet, except during courtship. The male utters a mep call during a display known as the burp, where he raises his head pointing his bill towards a female. The grunt-whistle is similar to that of mallards, where the male rears his outstretched head with the bill dipped into water, displacing a stream of water droplets towards a nearby female as the bill is raised against the chest. During this display the male makes a loud whistle call followed by a low burp. Paired males may follow other females in flight displays.

During nesting season, the female lays a clutch of 7–12 eggs with each of them measuring in length and in width. Incubation lasts for 24–27 days and the nestlings leave after around 1–2 days. A gadwall can only raise one brood a season

Because of the efforts of the United States and Canadian groups Ducks Unlimited, Delta Waterfowl Foundation and other private conservation groups, the species continues to be sustainably hunted there.

Further reading

  • Gadwall Duck Journal (Anas Strepera): 150 Page Lined Notebook/diary. N.p.: CreateSpace Publishing Platform, 2018. ISBN 9781724968739
  • RSPB Birds by Name Gadwall Page
  • Gadwall Species Account – Cornell Lab of Ornithology
  • Gadwall – Anas strepera – USGS Patuxent Bird Identification InfoCenter
  • Gadwal at the Massachusetts Breeding Bird Atlas
  • Feathers of gadwall (Anas strepera)