Coues's gadwall (''Mareca strepera couesi'') or the Washington Island gadwall, is an extinct

dabbling duck The Anatinae are a subfamily of the family Anatidae (swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a yo ...

which is only known by two immature specimens from the Pacific island of

Teraina Teraina (written also Teeraina, also known as Washington Island – these two names are constitutional) is a coral atoll in the central Pacific Ocean and part of the Northern Line Islands which belong to Kiribati. Obsolete names of Teraina a ...

,formerly known as Washington Island — Luther mentions a supposed occurrence on "New York Island", which is merely another old name of Teraina, however.

Line Islands The Line Islands, Teraina Islands or Equatorial Islands (in Gilbertese, ''Aono Raina'') are a chain of 11 atolls (with partly or fully enclosed lagoons) and coral islands (with a surrounding reef) in the central Pacific Ocean, south of the Haw ...

Kiribati Kiribati (), officially the Republic of Kiribati ( gil, ibaberikiKiribati),Kiribati
''The Wor ...

. They are in the

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with ...

Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...

The bird was named in honor of

Elliott Coues Elliott Ladd Coues (; September 9, 1842 – December 25, 1899) was an American army surgeon, historian, ornithologist, and author. He led surveys of the Arizona Territory, and later as secretary of the United States Geological and Geograph ...

Description

A male and a female are known, which resemble the immature appearance of the common gadwall except for the black bill with a higher number of fuiltering lamellae, black feet, and the much inferior size (which may be due to the birds not being fully grown). The male resembles a male common gadwall in

eclipse plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...

, save for some white speckling on the breast and back. The female looks like a small common gadwall female; the primary

wing covert A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are s ...

s were not patterned black, and the inner web of the secondary

remiges Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tai ...

was grey instead of white. Measurements are: wing, 19.9 cm; bill, 3.7 cm; tarsus 3.6 cm. This means the birds were the size of a

Cape teal The Cape teal (''Anas capensis'') also Cape wigeon or Cape widgeon is a 44–46 cm long dabbling duck of open wetlands in sub-Saharan Africa. Taxonomy The Cape teal was formally described in 1789 by the German naturalist Johann Friedrich G ...

or a

garganey The garganey (''Spatula querquedula'') is a small dabbling duck. It breeds in much of Europe and across the Palearctic, but is strictly migratory, with the entire population moving to southern Africa, India (in particular Santragachi), Banglad ...

, with a total length of 40–45 cm. As the birds were not fully adult when shot, it is not clear whether they would not have grown a bit larger.

Status and extinction

The status of this bird is controversial. While many scientists consider it a dwarf subspecies of the common gadwall (''Anas strepera strepera'') others argue that the two individuals might have been just juveniles of a local breeding population that might not even have been

taxonomically In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are gi ...

distinct. The common gadwall is a known vagrant to the

Tuamotu Islands The Tuamotu Archipelago or the Tuamotu Islands (french: Îles Tuamotu, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extendin ...

(Kolbe wrote "Tahiti which is a misreading of Greenway) and

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only ...

for example, which are about the same distance from the species' breeding grounds, as is Teraina (which, moreover, lies in between these two groups). This makes it entirely possible that the two Coues's gadwalls that were shot were just the offspring of a few vagrant common gadwalls, maybe settling there after being wounded by hunters. On the other hand, Streets' reports suggest that there was a population of these ducks of some size present, and thus they may have lived there for quite some time and indeed be worthy of recognition as a distinct

taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

The observations of the two individuals took place in January 1874.Bulletin – United States National Museum (1877) (description as ''Chaulelasmus couesi''). United States National Museum; Smithsonian Institution; United States. Dept. of the Interior The subspecies' description was by Thomas Hale Streets (1847–1925) in 1876. Streets reported about the two immatures he shot, which were found in a

peat bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...

. The cause of its extinction might be the extensive hunting by settlers of

Tabuaeran Tabuaeran, also known as Fanning Island, is an atoll that is part of the Line Islands of the central Pacific Ocean and part of Kiribati. The land area is , and the population in 2015 was 2,315. The maximum elevation is about 3 m (10 f ...

(Fanning Island), which had shot large numbers of migrant ducks on both Teraina and Tabuaeran each year. W. G. Anderson, a local resident stated in 1926 that growing up on Teraina and Tabueran around the turn of the century, he had never encountered a native population of gadwalls on Teraina. Thus, the subspecies' disappearance can be fixed to the last quarter of the 19th century, between the mid-1870s and 1900.

Description

Status and extinction

Notes

References

Further reading