Diamant à longue queue

Identification

The adult long-tailed finch is around 160 mm in length, the weight range of males is 13.5–16.2 grams and females 11.4–17.6 g. It has a prominent roundish black bib on its throat and upper chest and a long pointed black tail. It has pinkish brown upperparts with paler plumage below its bib over the lower breast and abdomen. It has a grey head, a white ear-patch, and black lores. It has black patches on its upper flanks and its rump and undertail coverts are white. The beak colour of the adult long-tailed finch varies from red through orange to yellow. Males and females are similar, except the females may be slightly duller and may have a slightly smaller bib. Females have shorter wings and tails than males on average, but their measurements, as well as throat bib size, generally lie within the range of male measurements. Furthermore, male and female plumage is indistinguishable in ultraviolet and visible light. A study published in 1999 showed that male long-tailed finches were unable to determine the sex of unfamiliar members of their species unless the latter bird declared its sex by song. Juveniles have black beaks and shorter tail feathers.<p>The subspecies are distinguished by the bill coloration, the nominate western group presenting a yellow colour and the eastern P. acuticauda hecki is red.

Taxonomie

The species Poephila acuticauda was first described by ornithologist John Gould in 1840, placing the new taxon as Amadina acuticauda. The specimen was collected by Benjamin Bynoe, the surgeon aboard HMS Beagle, at Derby on the north-west coast of Australia. It is one of three species in the genus Poephila. It is placed in the Australo-papuan finch family Estrildidae, although this family itself was previously placed in the sparrow family Passeridae.<p>A variety of subspecific arrangements had been regarded as colour variation across an east to west cline, although the geographically distinct morphology came to be acknowledged in the late twentieth century. Further support was given in a genetic study published in 2005 showed that the two subspecies of the long-tailed finch were separated from each other by the Kimberley Plateau–Arnhem Land Barrier around 340,000 years ago, and their ancestors diverged from the black-throated finch (P. cincta) across the Carpentarian Barrier 600 thousand years ago.<p>The Australian Faunal Directory recognises three Poephila species, arranged as two subgenera, the population is also separated as two subspecies. This treatment may be summarised as<p>genus Poephila<p>Common names for the species have been assigned or arisen from usage in aviculture, these include the long-tailed finch or longtail, blackheart finch, shaft-tail finch, orange-billed finch or grassfinch. Heck's grassfinch or finch, or Heck's longtail is applied to the eastern subspecies Poephila acuticauda hecki with red beaks, and the nominate subspecies with orange or yellow beaks is referred by the common name for the species.

Nom scientifique

Poephila acuticauda

Autorité

(Gould, 1840)

Ordre

Passériformes

Famille

Estrildidés

Genre

Poephila

Répartition et habitat

The long-tailed finch inhabits open woodland across northern Australia, from Derby in the northwest Kimberley region across to the east to the Leichhardt River in northwest Queensland.<p>It has an estimated global extent of occurrence of 1,000,000–10,000,000 km2. The IUCN has classified threats to the population of the species as being of least concern.

Migration

Espèce sédentaire

Comportement

Mode de migration: Espèce sédentaire.

Conservation

Tendance de la population: stable.

Tendance de la population

stable