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Identificazione

Black-headed tailorbirds are dark tailorbirds with a characteristic head pattern. The body mass ranges from 8–14 g (0.28–0.49 oz), with an average of 10.3 g (0.36 oz), and is roughly equal in both males and females. Older sources erroneously state the mean body mass as being 7 g (0.25 oz). Birds from Mindanao have a lower average body mass, 10.1 g (0.36 oz), than birds from Dinagat and Siargao, who have an average body mass of 10.6 g (0.37 oz). The average adult length is 12 cm (4.7 in). In O. n. nigriceps, the average wing length is 48.3 mm (1.90 in), the mean bill length is 10.8 mm (0.43 in), and the average tail length is 46.3 mm (1.82 in). In O. n. luminosus, the average wing length is 50.8–51.8 mm (2.00–2.04 in), the mean bill length is 10.8–10.9 mm (0.43–0.43 in), and the average tail length is 45.8–46.0 mm (1.80–1.81 in).<p>Black-headed tailorbirds show three distinct phenotypes, which correspond to different stages of maturity: adults having a 'black phenotype', immatures have a 'mottled phenotype', and juveniles have a 'grey phenotype'. Adults have dull black heads, necks, throats, and chests with a prominent white supercilium, line beneath the eye, and chin patch, although the chin patch is inconsistent and can sometimes be absent. Some adults have a small number of white feathers on the chin or abdomen retained from their immature plumage. The black blends into dull grey on the lower breast and belly, the latter having faint whitish tips to the feathers. The upperparts, flanks, and undertail coverts are olive-green and the tail is darker olive-green. The feathers of the wings are blackish with green edges; the region around the carpals is yellow and the median and greater upperwing coverts have brighter yellowish edges. The iris is chestnut-brown, the legs are pale pink, and upper and lower mandibles of the bill are blackish and whitish, respectively. Immature birds have the chin, throat, and upper breast whitish with light grey and black mottling, as well as a shorter tail with an average length of 38.5–41 mm (1.52–1.61 in). Juveniles have plain grey chins, throats, and upper breasts.<p>The species can be told apart from the white-eared tailorbird by its white supercilium, the absence of a white ear-spot, and its paler legs.<p>The tailorbird's call is a series of lengthy, stuttering trills that slows as it flattens out. It is like the song of the yellow-breasted tailorbird, but has a more "metallic ringing quality". Other calls include an anxious, falling ssiirrrrpppppp and a ringing key-e ei, the second of which is similar to the long-tailed bush warbler's song.

Tassonomia

The black-headed tailorbird was formally described in 1877 as Orthotomus nigriceps by the Scottish ornithologist Arthur Hay on the basis of a juvenile male specimen from Butuan on the island of Mindanao in the Philippines. In 1943, the Japanese ornithologist Masauji Hachisuka described O. nigrogularis as a new species based on an adult male specimen collected from the eastern Gulf of Davao, Mindanao. This specimen differed from the type of the black-headed tailorbird in having an entirely black throat and upper breast. O. nigrogularis was made a junior synonym of O. nigriceps in 1950 by the American ornithologist Sidney Dillon Ripley; Ripley referred to a 1947 paper by the German-American biologist Ernst Mayr, in which Mayr hypothesized that differences in throat color within the black-headed tailorbird could be attributed to sexual dimorphism. This became the conventional view for the next 70 years, despite Mayr's hypothesis having been made on the basis of a limited number of specimens. In 2022, the American ornithologist Matthew Halley studied a larger number of skins, showing the species was sexually monomorphic. Additionally, he found that specimens from the islands of Dinagat and Siargao differed from those from Mindanao in several characteristics, and described them as the subspecies O. n. luminosus. <p>The name of the genus is derived from the Ancient Greek orthotomeō, meaning 'to cut straight'. The specific epithet comes from the Modern Latin niger, meaning 'black', and -ceps, meaning '-headed'. Black-headed tailorbird is the official common name designated by the International Ornithologists' Union (IOU); the species is also known as the white-browed tailorbird.<p>The black-headed tailorbird currently has two subspecies recognized by the IOU, which differ in the color of their bellies, flanks, and tails.<p>The black-headed tailorbird is one of 13 species in the tailorbird genus Orthotomus. It has historically sometimes been considered to be the same species as the yellow-breasted and white-eared tailorbirds due to similarities in their vocalisations; however, these three species are genetically distinct, although they form a superspecies. According to a 2012 study of genetic data, the black-headed tailorbird is most closely related to the white-eared tailorbird, and these two species are further closest to the yellow-breasted tailorbird.

Nome scientifico

Orthotomus nigriceps

Autorità

Tweeddale, 1878

Ordine

Passeriformi

Famiglia

Cisticolidae

Genere

Orthotomus

Areale e habitat

The black-headed tailorbird is endemic to the southeastern Philippines, where it is found on the islands of Mindanao, Dinagat, and Siargao. On Mindanao, it is known from Agusan, Surigao, and eastern Davao. It inhabits dense undergrowth in lowland forests at elevations of up to 1,000 m (3,300 ft) and is non-migratory. A 2021 study of avian biodiversity near Mount Pantaron in Bukidnon found that the black-headed tailorbird, like other Philippine endemics, was absent from agricultural ecosystems but present in nearby montane forests. This suggests that the species may avoid habitats affected by human activities.

Migrazione

Resident species

Conservazione

Tendenza della popolazione

stable