The Black drongo (Dicrurus macrocercus) is a small Asian passerine bird The species is known for its aggressive behavior towards much larger birds that invade its territory. The Black drongo has been introduced to some Pacific islands, where it has thrived and become abundant to the point of threatening and causing the extinction of native and endemic bird species there.
Black drongos are glossy black birds 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. Black drongos fly with strong flaps of the wing and are capable of fast maneuvers 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.
Black drongos 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 make seasonal movements that are poorly understood; populations in Korea are known to be migratory. Black drongos inhabit open habitats such as savannas, shrublands, grasslands, fields, and urban areas.
Black drongos become active very early at dawn and roost later than many other birds. They feed late in the evening or night, often on insects attracted to artificial lights. Black drongos can often be seen sitting upright on thorny bushes, bare perches, or electricity wires. They may also perch on grazing animals. They usually perch and hunt close to the ground. Black drongos are mostly aerial predators of insects but also glean from the ground or off vegetation. They sometimes fly close to tree branches, attempting to disturb any insects that may be present. They congregate in fields being ploughed, picking up exposed caterpillars and beetle grubs. As many as 35 birds have been seen at such congregations. They are also attracted to fires in scrub and grasslands habitats where insects are disturbed. Black drongos often associate with Common mynas, Cattle egrets, and other birds that share a similar diet and habitat. Drongos benefit from this association and are more successful in their foraging. It is said that they imitate the call of the shikra so as to put mynas to flight and then steal prey. Black drongos are aggressive and fearless birds and will attack much larger species that enter their nesting territory, including crows and even birds of prey. This behavior led to their former name of “king crow”. Black drongos have a wide range of calls but their most common call is a two-note ‘tee-hee’ call.
No comments:
Post a Comment