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The Gadwall (Anas strepera) is a common and widespread duck of the family Anatidae. This species was first described by Linnaeus in his Systema naturae in 1758 under its current scientific name. Its conservation status is Least Concern.

Description

The Gadwall is 46–56 cm (18–22 in) long with a 78–90 cm (31–35 in) wingspan. The male is slightly larger than the female, weighing on average 990 g (35 oz) against her 850 g (30 oz). The breeding male is patterned grey, with a black rear end, light chestnut wings, and a brilliant white speculum, obvious in flight or at rest. 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 moults annually, following a juvenile moult.



Distribution

The Gadwall breeds in the northern areas of Europe and Asia, and central North America. In North America, its breeding range lies along the Saint Lawrence Rivermarker, through the Great Lakesmarker, Albertamarker, Saskatchewanmarker, the Dakotasmarker, south to Kansasmarker, west to Californiamarker, and along coastal Pacificmarker Canadamarker and southern coastal Alaskamarker. 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 Alaskamarker, south into Central America, and east into Idahomarker, Kansasmarker, Ohiomarker, Virginiamarker, and then south all the way into Central America.

In Great Britainmarker, the Gadwall is a scarce-breeding bird and winter visitor, though its population has increased in recent years. It is likely that its expansion was partly through introduction, mainly to Englandmarker, and partly colonization Great Britainmarker, with continental birds staying to breed in Scotlandmarker.

Behaviour and habitat

Pair up-ending in Kolkata
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. 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. This is a fairly quiet species; the male has a hoarse whistling call, and the female has a Mallard-like quack. The young birds are fed insects at first; adults also eat some molluscs and insects during the nesting season. The Gadwall is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

Taxonomy

The Gadwall’s closest relative within the genus Anas is the Falcated Duck, followed by the wigeons.

There are two sub-species although one is extinct:
  • A. strepera strepera, Common Gadwall the nominate subspecies.
  • A. strepera couesi, Coues' Gadwall, extinct circa 1874, was located on Fanning Islandmarker.


The etymology of the word Gadwall is not known but the term has been in usage from around 1666.

Footnotes

  1. Linnaeus, C. (1758) p.125
  2. Floyd, T (2008)
  3. Madge (1988) pp.200–202
  4. Dunn, J. (2006)
  5. Clements, J. (2007)
  6. Merriam Webster online


References

  • Clements, James, (2007) The Clements Checklist of the Birds of the World, Cornell University Press, Ithaca
  • Dunn, J. & Alderfer, J. (2006) National Geographic Field Guide to the Birds of North America 5th Ed.
  • Floyd, T (2008) Smithsonian Field Guide to the Birds of North America Harper Collins, New York


External links




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