Anas strepera

Anas strepera

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Aves
Subclassis: Carinatae
Infraclassis: Neornithes
Parvclassis: Neognathae
Ordo: Anseriformes
Familia: Anatidae
Subfamilia: Anatinae
Genus: Anas
Species: Anas strepera
Subspecies: †A. s. couesi - A. s. strepera

Name

Anas strepera Linnaeus, 1758

References

* Syst.Nat.ed.10 p.125
* Anas strepera Report on ITIS

Vernacular names
Internationalization
Български: Сива патица
Česky: Kopřivka obecná
Cymraeg: Hwyaden Lwyd
Deutsch: Schnatterente
Ελληνικά: Καπακλής
English: Gadwall
Esperanto: Knaranaso
Español: Ánade friso
Eesti: Rääkspart
Français: Canard chipeau
Frysk: Eastein
Galego: Pato cinsento
Magyar: Kendermagos réce
Italiano: Anas strepera
日本語: オカヨシガモ
한국어: 알락오리
Lietuvių: Pilkoji antis
Nederlands: Krakeend
‪Norsk (bokmål)‬: Snadderand
Polski: Kaczka krakwa
Русский: Серая утка
Sámegiella: Ránessnárttal
Slovenčina: Kačica chripľavá
Suomi: Harmaasorsa
Svenska: Snatterand
Türkçe: Boz ördek
Vèneto: Mezan

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.[2]


Description


The Gadwall is 46–56 cm (18–22 in) long with a 78–90 cm (31–35 in) wingspan.[3] The male is slightly larger than the female, weighing on average 990 g (35 oz) against her 850 g (30 oz).[4] 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.[5] 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.[4]

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.[5] Both sexes go through two moults annually, following a juvenile moult.[3]

The Gadwall is a quieter duck, except during its courtship display. Females give a call similar to the quack of a female Mallard but higher-pitched, transcribed as gag-ag-ag-ag. Males give a grunt, transcribed as nheck, and a whistle.[4]
A drake

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 River, through the Great Lakes, Alberta, Saskatchewan, the Dakotas, south to Kansas, west to California, and along coastal Pacific Canada and southern coastal Alaska.[3][5] 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.[3][5] Its conservation status is Least Concern.[1]

In Great Britain, 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 England, and partly colonization Great Britain, with continental birds staying to breed in Scotland. It has been reported in the River Avon (Hampshire).

Behaviour


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.[6]

There are two sub-species although one is extinct:

* A. strepera strepera, Common Gadwall the nominate subspecies.[7]
* †A. strepera couesi, Coues' Gadwall, extinct circa 1874, was located on Fanning Island.[7]

The etymology of the word Gadwall is not known but the term has been in usage from around 1666.[8]

References

1. ^ a b BirdLife International, 2009
2. ^ Linnaeus, 1758, p. 125
3. ^ a b c d Floyd, 2008[page needed]
4. ^ a b c Madge and Burn, 1988, pp. 200–202
5. ^ a b c d Dunn and Alderfer, 2006[page needed]
6. ^ Johnson and Sorenson, 1999
7. ^ a b Clements, 2007[page needed]
8. ^ Merriam Webster online


Literature cited

* BirdLife International (2009). "Anas strepera". IUCN Red List of Threatened Species. Version 2009.2. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/141496.
* Clements, James (2007). The Clements Checklist of the Birds of the World. Ithaca: Cornell University Press. http://www.cornellpress.cornell.edu/cup_detail.taf?ti_id=4566.
* Floyd, T (2008). Smithsonian Field Guide to the Birds of North America. New York: HarperCollins.
* Johnson, Kevin P; Sorenson, Michael D (July 1999). "Phylogeny and biogeography of dabbling ducks (genus: Anas): A comparison of molecular and morphological evidence" (PDF). The Auk 116 (3): 792–805. http://elibrary.unm.edu/sora/Auk/v116n03/p0792-p0805.pdf.
* Linnaeus, C (1758) (in Latin). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.. Holmiae. (Laurentii Salvii). "A. macula alarum rufa nigra alba."
* Madge, Steve; Burn, Hilary (1988). Wildfowl: An Identification Guide to the Ducks, Geese and Swans of the World. Christopher Helm. pp. 222–224. ISBN 0-7470-2201-1.

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