Black-faced Woodswallow

Identificazione

The black-faced woodswallow is 18–19 cm (7.1–7.5 in) in length, and weighs 32–40 g (1.1–1.4 oz). It has a blue-grey beak with a black tip and a black face mask which extends from the base of the bill up to and around the eyes. It has ash grey plumage, which is lighter around the breast with darker wings, and silver underwings. The tail is black with a white tip.<p>The subspecies are differentiated by black or white colouration of their tail vents. The white-vented subspecies A. c. normani and A. c. inkermani are found on the Cape York Peninsula and northern Queensland respectively. The black-vented A.c. cinereus occurs in south west Australia, while A. c. melanops occurs in northern Australia and Lesser Sunda Islands, including Timor. The sexes are similar in colouration. Juvenile woodswallows have a brown body and wing coloration with buff streaks and a pale yellow beak. The voice is soft with chiff, chap and chattering animated calls which can include vocal mimicry.

Tassonomia

The black-faced woodswallow was formally described in 1817 by the French ornithologist Louis Pierre Vieillot and given the current binomial name Artamus cinereus. The specific epithet is Latin meaning "ash-grey" or "ash-coloured". Although Vieillot gave the locality as the island of Timor, he had copied the description by the Dutch zoologist Coenraad Jacob Temminck of the "L'angroyan gris" from "la nouvelle Galle meridionale" (New South Wales) that had been published in 1807. Temminck mentioned that the central tail feathers were entirely black which is consistent with Australian race and but not with the race found on Timor where the central tail feathers have white tips. Temminck's specimen is preserved in the Rijksmuseum van Natuurlijke Historie in the Netherlands. In 1982 Gerlof Mees designated this as a lectotype and transferred the name cinereus from the race on Timor to the race found in southwest Australia.<p>Five subspecies are recognised:<p>Within Australia the Great Dividing Range, the Gregory Range and the eastern edge of the Carpentarian grasslands separates the range of the two subspecies. To the east of the range are the subspecies with white vents, while to the west are the black vented subspecies. There have been reported hybrid populations, along territory borders with hybrid zones, where genetic exchange, detected phenotypically using the hybrid index score, has occurred. Of note, the black-vented woodswallows are more adapted to arid and semi-arid conditions, while the white-vented are adapted to tropical conditions. Therefore, selection pressure will probably not result in subspecies merging. The role of possible isolation of an ancestral subpopulation with subsequent expansion after glacial factors during the Pleistocene and environmental factors in generating the different plumage patterns has been considered. Molecular phylogeography using mitochondrial DNA in woodswallows was not helpful in determining biogeographical factors. Mitochondrial DNA studies revealed random intermixing. There are no current studies using nuclear DNA. This confirms that multiple criteria such as plumage, song, and mtDNA, nDNA and interbreeding determine species and subspecies.

Nome scientifico

Artamus cinereus

Autorità

Vieillot, 1817

Ordine

Passeriformi

Famiglia

Artamidae

Genere

Artamo

Areale e habitat

This species is broadly distributed in Australia, occupying most of the continent except for the southeastern margin near its coast. It is mainly sedentary, remaining in arid and semi-arid areas even during dry conditions. Although it can be partly nomadic, the woodswallow prefers open eucalypt woodlands, scrub, and spinifex in arid and semi-arid conditions. In tropical savannah, it prefers open woodlands and grasslands. Woodswallows frequently flock with finches and at times the golden-shouldered parrot.

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in aumento.

Tendenza della popolazione

in aumento