Gallinella della Tasmania

Identificazione

The Tasmanian nativehen is a stocky flightless bird between 43 and 51 centimetres (17 and 20 in) in length. The upperparts are olive-brown with a white patch on the flank. The underparts are darker with a bluish-grey tinge. The short tail is close to black and mostly held erect. The legs are thick and powerful, with a grey scaly appearance and sharp claws. The eyes are bright red. The bill has a small greenish-yellow frontal shield.<p>The juvenile bird is similar in appearance to the adult, though the colours are more subdued on the body and the underparts have fine white spots. The bill is greenish-yellow and the eyes bright red. Male birds generally have longer bills and legs, though there is enough overlap that the sexes are indistinguishable, even in the hand.<p>The species has 14 separate calls, ranging from low grunts to high pitched alarm calls as well as a see-sawing duet performed in unison, rising to a crescendo of harsh screeching notes, It also calls at night.

Tassonomia

Nome scientifico

Tribonyx mortierii

Autorità

Du Bus de Gisignies, 1840

Ordine

Gruiformi

Famiglia

Rallidae

Genere

Tribonyx

Areale e habitat

The species is endemic to, and widespread in, Tasmania apart from the west and south-west regions. It is sedentary, living around open grassy areas close to water. It is not found on King or Flinders Island in the Bass Strait, though Michael Sharland does record it as being on Flinders Island. A population introduced to Maria Island is now well established. It is generally common and easily seen around bodies of water that have grassy verges.<p>Fossil records indicate that it was found on the Australian mainland until around 4700 years ago. Suggested reasons for its extirpation have included human overhunting, the introduction of the dingo, or an extremely dry period.

Migrazione

Resident species

Conservazione

The species is currently classified as a species of least concern by the IUCN. Although there is a healthy population size and no significant falls have been measured, there is concern about the possible arrival of the red fox in Tasmania and the potential impact that it would have on this and other species.<p>Since 15 August 2007 it has been protected under Tasmanian legislation. Prior to this it was one of only four native birds that had no legal protection in the state of Tasmania outside national parks and other reserves — the last of Tasmania's 12 endemic bird species with this dubious status. The three remaining unprotected native species are the forest raven, the great cormorant, and the little pied cormorant. All other native Tasmanian birds are listed as protected under the state's Nature Conservation Act 2002.

Tendenza della popolazione

unknown