Banded Stilt

Identificazione

The banded stilt is 45–53 cm (18–21 in) long and weighs 220–260 g (7.8–9.2 oz), with a wingspan of 55–68 cm (22–27 in). Adults in breeding plumage are predominantly white with black wings and a broad well-demarcated u-shaped chestnut band across the breast. The central part of the base of the upper tail is tinted a pale grey-brown. The slender bill is black, relatively straight, and twice as long as the head. The irises are dark brown and the legs and feet are a dark red-pink. The wings are long and slim and have eleven primary flight feathers, with the tenth being the longest. In flight, the wings are mostly black when seen from above, but have a white trailing edge from the tips of the inner primaries. From underneath, the wings are predominantly white with dark tips. White feathers on the head and neck have pale grey bases, which are normally hidden. Non-breeding plumage is similar, but the chest band is less distinct and often diluted to an ashy brown or mottled with white. The legs are a paler- or orange-pink. There is no difference in plumage between the sexes, nor has any geographic variation been recorded.<p>Juvenile birds resemble adults but have a greyish forehead and lores, duller black wings, and lack the characteristic breast band. Adult plumage is attained in the second year. Their legs and feet are grey, becoming more blotched with pink until adulthood. Nestling banded stilts are covered in white down.<p>A distinctive bird, the banded stilt is hard to confuse with any other species; the white-headed stilt lacks the breast band, and the red-necked avocet has a chestnut head and neck, and a distinctly upcurved bill.<p>Adults make a barking call that has been written as cow or chowk, sometimes with two syllables as chowk-uk or chuk-uk. Birds also chatter softly and tunefully while nesting.

Tassonomia

French ornithologist Louis Pierre Vieillot described the banded stilt in 1816, classifying it in the avocet genus Recurvirostra and giving it the name Recurvirostra leucocephala, "L'avocette a tete blanche" ("white-headed avocet"). He only recorded the species as being found in terres australes, the meaning of which is unclear. Amateur ornithologist Gregory Mathews interpreted this as Victoria, while Erwin Stresemann concluded this was Rottnest Island in Western Australia. The species name is derived from the Ancient Greek words leukos "white", and kephale "head". French naturalist Georges Cuvier described it as Recurvirostra orientalis the same year. Belgian ornithologist Bernard du Bus de Gisignies described it as a new genus and species, Leptorhynchus pectoralis, to the Royal Academy of Belgium in 1835.<p>English zoologist George Robert Gray placed the banded stilt in its own genus Cladorhynchus in 1840, noting that the name Leptorhynchus had been previously used. The genus name is from the Ancient Greek klados "twig" and rhynchos"bill". Likewise, German naturalist Johannes Gistel proposed the name Timeta to replace Leptorhynchus in 1848. John Gould had described the banded stilt as Himantopus palmatus in 1837, but recorded it as Cladorhynchus pectoralis in his 1865 work Handbook to the Birds of Australia. Gould also wrote that its distribution was unclear after it was first recorded at Rottnest Island though not elsewhere in Western Australia, and later in South Australia, until large numbers were seen by the British explorer Charles Sturt at Lepson's Lake north of Cooper Creek in what is now western Queensland. German naturalist Ludwig Reichenbach placed it in a new genus, naming it Xiphidiorhynchus pectoralis in 1845. Australian ornithologist Fred Lawson gave it the name Cladorhynchus australis in 1904. Gregory Mathews in his 1913 List of the Birds of Australia synonymised all subsequent genus and species names, using Cladorhynchus australis. He listed his subspecies rottnesti from 1913, though this has not been recognised since. Both Joseph G. Strauch in a 1978 study and Philip C. Chu in a 1995 re-analysis of bone and muscle characters found that the banded stilt was sister taxon to the avocets, with the stilts of the genus Himantopus an earlier offshoot. A 2004 study combining genetics and morphology reinforced its position as sister to the avocet lineage.<p>English naturalist John Latham gave the bird the name "oriental avocet" in 1824, after Cuvier's description. "Banded stilt" has been designated the official name by the International Ornithological Committee (IOC). Other common names include "Rottnest snipe" and "bishop snipe". The Ngarrindjeri people of the Lower Murray River region in South Australia knew it as nilkani.

Nome scientifico

Cladorhynchus leucocephalus

Autorità

(Vieillot, 1816)

Ordine

Caradriformi

Famiglia

Recurvirostridae

Genere

Cladorhynchus

Areale e habitat

The banded stilt is generally found in southern Australia. In Western Australia, it is found predominantly in the southwestern corner, though can be as far north as the saltworks in Port Hedland. Breeding took place at Lake Ballard in the Goldfields-Esperance after heavy rainfall from Cyclone Bobby in 1995, and then again after flooding in 2014. In 1933 a large colony had been recorded at Lake Grace, but had succumbed to attack presumably by foxes. The banded stilt has been recorded in southeastern South Australia, as well as the drainage of the Lake Eyre system, and in Victoria west of Port Phillip and the Wimmera. In July 2010 Lake Torrens filled with water, resulting in the influx of around 150,000 banded stilts. The Natimuk-Douglas Wetlands in western Victoria are an important nesting ground for the species, though lower numbers come here if there is flooding elsewhere in southeastern Australia. In New South Wales, it is most commonly found in the Riverina and western parts of the state, and has reached southern Queensland and the Northern Territory, where it has been found at the sewage ponds at Alice Springs and Erldunda. It has been recorded as a vagrant to Tasmania, with significant numbers recorded in 1981.<p>The preferred habitats are large, shallow saline or hypersaline lakes, either inland or near the coast, including ephemeral salt lakes, salt works, lagoons, salt- or claypans and intertidal flats. The species is occasionally found in brackish or fresh water, including farm dams and sewage ponds.<p>The banded stilt is highly nomadic, having adapted to the unpredictable climate of Australia's arid interior. Sudden rainfall results in the influx of water to and filling of dry inland salt lakes. The stilts respond by travelling to these areas and breeding, dispersing and returning to the coast once the lakes begin to dry up. How banded stilts on the coast become aware of inland rainfall is unknown. The distances travelled can be large; two birds have been tracked travelling from a drying Lake Eyre in South Australia to a newly filled lake system in Western Australia over 1,500 km (930 mi) away. One of these birds veered northwest over the Gibson Desert, travelling a minimum of 2,263 km (1,406 mi) in 55.9 hours.

Migrazione

Specie stanziale

Comportamento

Comportamento migratorio: Specie stanziale.

Conservazione

Tendenza della popolazione: stabile.

Tendenza della popolazione

stabile