Black Drongo

识别特征

This bird is glossy black with a wide fork to the tail. Adults usually have a small white spot at the base of the gape. The iris is dark brown (not crimson as in the similar ashy drongo). The sexes cannot be told apart in the field. Juveniles are brownish and may have some white barring or speckling towards the belly and vent, and can be mistaken for the white-bellied drongo. First-year birds have white tips to the feathers of the belly, while second-years have these white-tipped feathers restricted to the vent.<p>They are aggressive and fearless birds, and although only 28 cm (11 in) in length, they will attack much larger species that enter their nesting territory, including crows and birds of prey. This behaviour led to their former name of king crow. They fly with strong flaps of the wing and are capable of fast manoeuvres that enable them to capture flying insects. With short legs, they sit upright on thorny bushes, bare perches or electricity wires. They may also perch on grazing animals.<p>They are capable of producing a wide range of calls but a common call is a two note tee-hee call resembling that of the shikra (Accipiter badius).

分类信息

The black drongo was once considered a subspecies of the fork-tailed drongo (Dicrurus adsimilis), a close relative that diverged relatively recently. The two are now considered distinct species, with the fork-tailed drongo restricted to Africa and separated from the Asian range of the black drongo.<p>Seven subspecies have been named but the largely contiguous populations show clinal variation and intergrade with each other. Individuals from northern India (ssp. albirictus) are larger than those from the Sri Lankan population minor while those from the peninsular India (nominate subspecies) are intermediate in size. Race cathoecus is found in Thailand, Hong Kong and China. This race has a much smaller rictal spot and the wings are dark with a greenish gloss. In southern Siam a race thai is resident, but overlaps with wintering cathoecus. Race javanus is found on the islands of Java and Bali. Race harterti found in Formosa has the tail length less than the wing.

学名

Dicrurus macrocercus

命名信息

Vieillot, 1817

目

Passeriformes

科

Dicruridae

属

Dicrurus

分布与栖息地

The black drongo is found predominantly in open country and usually perches and hunts close to the ground. They are mostly aerial predators of insects but also glean from the ground or off vegetation. They are found as summer visitors to northeastern Afghanistan and northern Pakistan but are residents from the Indus Valley until Bangladesh and into India and Sri Lanka. Some populations show seasonal movements that are poorly understood while populations in Korea are known to be migratory. The black drongo can be found in savanna, fields, and urban habitats.<p>Black drongos were introduced just before the Second World War from Taiwan to the island of Rota to help in the control of insects. It is believed that they dispersed over the sea to the island of Guam in the 1950s. By 1967, they were the fourth most commonly seen birds in roadside counts on Guam and are today the most abundant bird there. Predation by and competition from black drongos have been suggested as factors in the decline of endemic bird species such as the Rota bridled white-eye and the Guam flycatcher.

迁徙

Complete migrants

行为

Migration pattern: Complete migrants.

保护状况

种群趋势

unknown