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The American black duck (Anas rubripes) is a large dabbling duck in the family Anatidae. It was described by William Brewster in 1902. It is the heaviest species in the genus Anas , weighing 720–1,640 g (1.59–3.62 lb) on average and measuring 54–59 cm (21–23 in) in length with an 88–95 cm (35–37 in) wingspan .
The Pacific black duck (Anas superciliosa) is a dabbling duck found in much of Indonesia, New Guinea, Australia, New Zealand, and many islands in the southwestern Pacific, reaching to the Caroline Islands in the north and French Polynesia in the east. It is usually called the grey duck in New Zealand, where it is also known by its Maori name ...
Puddle ducks spring straight up from the water, but diving ducks need to gain momentum to take off, so they must run across the water a short distance to gain flight. Traditionally, most ducks were assigned to either the shelducks , the perching ducks , and the dabbling and diving ducks ; the latter two were presumed to make up the Anatinae.
The word duck comes from Old English dūce 'diver', a derivative of the verb *dūcan 'to duck, bend down low as if to get under something, or dive', because of the way many species in the dabbling duck group feed by upending; compare with Dutch duiken and German tauchen 'to dive'. Pacific black duck displaying the characteristic upending "duck"
African black duck. The African black duck is a black duck with pronounced white marks on its back, a dark bill, and orange legs and feet. A purpish-blue speculum is often visible, especially in flight. It lives in central and southern Africa. It is also known as the black river duck, or (A. s. leucostigma) West African black duck or Ethiopian ...
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The black scoter or American scoter (Melanitta americana) is a large sea duck, 43 to 49 cm (17 to 19 in) in length. The genus name is derived from Ancient Greek melas "black" and netta "duck". The species name is from the Latin for "American".
The retention of ancestral genetic variation can be caused by incomplete lineage sorting (ILS) and introgression after secondary contact. These two factors can cause genetic variation to be shared between closely related species which is possibly why an American black duck or a Mottled duck (Anas fulvigula) may have notable white on its speculum or a Mexican duck may have flecks of green.