The Black Drongo (Dicrurus macrocercus), also known as the King Crow, is a small Asian passerine bird of the drongo family Dicruridae. Previously considered a subspecies (Dicrurus adsimilis macrocercus) of the African Fork-tailed Drongo (Dicrurus adsimilis), it is now recognized as a full species. It is a common resident breeder in much of tropical southern Asia from southwest Iran through India and Sri Lanka east to southern China and Indonesia. It is a wholly black bird with a distinctive forked tail and measures 28 cm (11 in) in length. Feeding on insects, it is common in open agricultural areas and light forest throughout its range, perching conspicuously on a bare perch or along power or telephone lines. The species is famous for its aggressive behaviour towards much larger birds, such as crows, never hesitating to dive-bomb any birds of prey that invades its territory. Smaller birds often nest in the well guarded vicinity of a nesting Black Drongo. 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.
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.
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.
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).
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. The Black Drongo can be found in savannas, fields, and urban habitats.
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.
Growth and development
Young birds have a yellowish-red gape. The feather follicles appear on the fourth day and pin feathers emerge after a week. Nestlings increase in weight steadily until they are 12 days old. The eyes open on the eighth day, the iris reddish-black while the gape turns red. The young leave the nest on the 16 or 17th day. They do not have the fork in the tail until three weeks. The parents continue to feed and protect them for a month. Young birds may beg for food for longer, but are often ignored or chased away by the adults. Birds reach breeding condition in about two years.
Play behaviour has been observed with birds dropping a leaf in the air and catching it in mid-air and these may possibly help young birds acquire aerobatic skills.
In southern India, they moult their feathers from June to October. The wing moult begins in July with the first primary and proceeds towards the tenth. Secondaries are replaced from August after the primaries are at the third quill. The secondary moult is not orderly, the 8th and 7th being dropped earlier than the rest. The tail feathers are moulted rifugally. Seasonal colour changes in the testicular tissues are caused by variation in melanin synthesis, with the dark pigmentation being lost during the breeding season.