Torrentero Dorsigrís

Identificación

The slaty-backed forktail is a slim, medium-sized forktail between .mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}22 and 25 centimetres (8+5⁄8 and 9+7⁄8 in) long, and weighs between 26 and 38 grams (0.92 and 1.34 oz). It is coloured slate-grey, black, and white. The bill is black, while the feet of the bird are a pale pinkish or greyish colour. The iris has been described as dark brown, though it has been recorded as black in certain specimens. It has a black throat and a narrow white stripe across its face till just behind the eyes, sometimes describe as a white mask. The white stripe sometimes includes a white eye ring, which may be either complete or partial. Its ear coverts, chin, and face are also black. The forehead, crown, sides of the neck, and the scapulars are slate grey. It has black wing-coverts, a white patch at the base of the primaries, wide white bars on otherwise black wings, and also a large white patch on its rump and lower back. The bases of the flight feathers are white, which is occasionally visible as a little additional bar on the wing. The tail of the bird is long and evenly graduated, with a deep fork. The tail is largely black except for a white tip. It also has three white bands along its length, formed by the white tips of shorter tail feathers.<p>The juvenile of the species lacks a white forehead, is brown above, and has dark scales on its breast. The tail of the juvenile is shorter than that of the adult: juveniles also have greyish or yellowish lores, and greyish or white chin and throat. The flanks are a dull grey-brown. It is not sexually dimorphic. Some specimens have been observed to have white tips to their primaries. This feature has been hypothesized to be the result of aging or of wear and tear, and has been observed throughout the distribution of the species. It is known not to be sex-related. Though very similar to the black-backed forktail Enicurus immaculatus, it is distinguished by its slate-grey mantle and crown, from which it gets its name. It also has a slightly larger bill than the black-backed forktail, and slightly less white on its forehead.<p>One of the slaty-backed forktail's calls has been described as a "high, thin, sharp, metallic screech, ''teenk'", similar to that made by a small kingfisher; in particular, it has been mistaken for the call of the Blyth's kingfisher Alcedo hercules. Another call is described as a mellow "cheet". It also produces a repeated, harsh screeching call when alarmed.

Taxonomía

The slaty-backed forktail was described scientifically in 1836 by British naturalist Brian H. Hodgson. It was originally placed in a new subgenus Enicurus in the genus Motacilla, which contains the wagtails. The specimen used to describe the species came from Nepal. The species name is the Latin adjective schistaceus "slaty-grey". The slaty-backed forktail is currently placed within the family Muscicapidae, which includes Old World flycatchers and chats. A genetic study found that the slaty-backed forktail and the little forktail were genetically more distinct from the white-crowned forktail than were other forktail species.

Nombre científico

Enicurus schistaceus

Autoridad

(Hodgson, 1836)

Orden

Passeriformes

Familia

Muscicápidos

Género

Enicurus

Distribución y hábitat

The slaty-backed forktail is found near fast-flowing water bodies in tropical and sub-tropical montane broadleaf forests, as well as near cultivated areas. These include rocky streams and rivers, including broad rivers and valleys in plains areas. A 2000 paper studying birds in northwest India and Nepal found that the incidence of slaty-backed forktails decreased with altitude. The study also found that the slaty-backed forktail had a preference for streams that were bordered by dense and complex vegetation, and had firm and stable banks of earth. They also preferred streams with finer grained sand on the bottom, and with "pool–riffle sequences." More rarely the bird is seen in secluded areas of the forest, and on the sides of roads or trails near the water. In winter months it has been observed to move from the mountains into foothills and plains areas.<p>The species is found in the central and eastern Himalayas, from the Indian state of Uttarakhand in the west to Myanmar in the East, including Nepal, and Bhutan. It is a vagrant in Bangladesh. It is also found in southern China, in southeast Tibet, and in the provinces of Sichuan, Yunnan, Guizhou, Fujian and Zhejiang, and possibly in Hainan. Its range in South-East Asia includes Thailand, Vietnam, Laos, Cambodia, peninsular Malaysia, and Hong Kong. In Hong Kong, it is only an occasional winter visitor or highly uncommon resident. Its distribution in southeast Asia is discontinuous. The elevational range of the slaty-backed forktail varies geographically. It has been estimated as 300-1600m above sea level in northern India, 900–1675 in Nepal, 400–1800 in southern China and the adjacent areas of Thailand, above 500m in Cambodia, above 800m in Malaysia, and 800-2200m in Bhutan. In the winter, it has been recorded as low as 200m above sea level.<p>The range of the species has not been precisely determined, but is known to be very large. The population is thought to be stable, and though its size is not precisely known, it is thought to be greater than 10,000 individuals. It is categorized as a species of least concern by the International Union for Conservation of Nature. It is common in the parts of its range that occur in China, Nepal, and South-East Asia.

Migración

Especie residente

Comportamiento

Patrón migratorio: Especie residente.

Conservación

Tendencia poblacional: estable.

Tendencia poblacional

estable