Anatra becco macchiato indiana

Identificazione

This duck is around the same size as a mallard and has a scaly patterned body with a green speculum bordered by white. At rest the white stripe stands out and the long neck and the bill with yellow tip and orange red spots at the base are distinctive in the nominate subspecies. In flight it is distinguished by the green speculum with a broad white band at the base. The red spots at the base of the bills are absent in haringtoni. It measures 55–63 cm (22–25 in) in length and 83–95 cm (33–37 in) across the wings, with a body mass of 790–1,500 g (1.74–3.31 lb). These are mainly grey ducks with a paler head and neck and a black bill tipped bright yellow. The wings are whitish with black flight feathers below, and from above show a white-bordered green The male has a red spot on the base of the bill, which is absent or inconspicuous in the smaller but otherwise similar female. The male does not have an eclipse plumage. The legs and feet are bright orange to coral red. Juveniles are browner and duller than adults.<p>The eastern spot-billed duck is darker and browner; its body plumage is more similar to the Pacific black duck. It lacks the red bill spot, and has a blue speculum.<p>Both males and females undergo a complete post-breeding moult, dropping all their wing feathers simultaneously.

Tassonomia

The Indian spot-billed duck was described by the naturalist Johann Reinhold Forster in 1781 under its current binomial name Anas poecilorhyncha. The name of the genus Anas is the Latin word for a duck. The specific epithet poecilorhyncha combines the classical Greek words poikilos meaning "pied" or "spotted" and rhunkhos meaning a "bill".<p>A molecular phylogenetic study published in 2009 that compared mitochondrial DNA sequences from ducks, geese and swans in the family Anatidae found that the Indian spot-billed duck was a sister species to a clade containing the Mexican duck, the American black duck, the mottled duck and the mallard. A 2014 study, however, shows that there is discordance between the phylogenies obtained using nuclear DNA sequences; the Indian spot-bill appears to be closer to the Laysan and Hawaiian ducks and forming a sister clade to the New World and Old World mallards and the Mexican, American black and mottled ducks. There is significant hybridization between Old World mallards and eastern spot-billed ducks, leading to a closeness in their mitochondrial DNA that alters the apparent phylogenies.<p>Two subspecies are recognised although intergradation is possible (intermediates between haringtoni and eastern spot-billed duck have been recorded):<p>The eastern spot-billed duck was formerly considered as a third subspecies. Fieldwork carried out at Hong Kong in southern China and published in 2006 found that although both the eastern spot-billed duck and the Indian spot-billed duck (subspecies A. p. haringtoni) bred in the region at the same time, mixed pairs were only very rarely observed. Based on this observation most taxonomists now treat the eastern spot-billed duck as a separate species.

Nome scientifico

Anas poecilorhyncha

Autorità

Forster, JR, 1781

Ordine

Anseriformi

Famiglia

Anatidae

Genere

Anas

Areale e habitat

This duck is a resident throughout Pakistan and India in freshwater wetlands. They tend to avoid very large patches of open water and prefer medium-sized wetlands with vegetation cover. Some individuals may however migrate as a bird ringed at Bharatpur in Rajasthan on 5 December 1969 was recovered near Novosibirsk in August 1970. It is quite gregarious outside the breeding season and forms small flocks. The northernmost populations have expanded their range northwards by more than 500 km since the early 20th century, possibly in reaction to global warming.

Migrazione

Complete migrants

Conservazione

Tendenza della popolazione

declining