DRONGOS: Dicruridae

PHYSICAL CHARACTERISTICS

Drongos are small to medium sized, crow-like birds, usually very dark gray to black all over, a few species being light gray. Black plumage (feathers) shimmers with iridescent green, deep blue, or purple, or the plumage may show spangles, or colored, iridescent spots. The eyes are vivid red or orange, usually a giveaway that the bird is a drongo and not some unrelated black bird. The tail is typically long, often forked, with a complex, ornate shape. The head in most species bears some sort of crest. Body length in drongos ranges from 7 to 15 inches (18 to 38 centimeters) among species.

The beak resembles that of jays, being robust, hooked, notched behind the hooked end, and black in most species. There are long bristles, or retrices (REH-truh-suhz), around the base of the beak. The wings are long and rounded or pointed. The legs, black in most species, are short, with strong feet and toes. Males are slightly larger than females, but both sexes are identical, or show slight variation, in coloration.

GEOGRAPHIC RANGE

Tropical Africa, Madagascar, Asia, Australia, New Guinea, Java, Taiwan, Solomon Islands.

HABITAT

Tropical rain forest, mixed open forest and grassland.

DIET

Drongos eat mainly insects, but sometimes spiders, small birds, and nectar.

BEHAVIOR AND REPRODUCTION

Drongos are notorious for aggressive behavior. They will fiercely defend their nests, and attack or harass predators like birds of prey, hornbills, crows, snakes, and humans. Drongos are accomplished, acrobatic flyers. In one recorded instance, a drongo individual escaped the clutches of a little sparrowhawk, which was chasing it in mid-air, by aerial acrobatics, outmaneuvering the predator.

Drongos forage, search for food, alone, in pairs, or in groups. The birds catch insects in mid-flight, often following larger animals such as deer, cattle, or monkeys in order to catch insects flushed out by the larger animals' motions. They may even follow grass fires, snagging insects escaping the flames. Drongos also glean (pluck) insects from foliage and probe under bark for insects and related creatures. They may also forage in mixed-species flocks of one or more other bird species. Some drongo species just share in the abundance of insects driven out of hiding by the mixed-species flocks. Other species, especially during lean times, join mixed-species flocks but engage in kleptoparasitism, stealing food from other birds. They rob either directly, or, as in the forktailed drongos, by distracting another bird with alarm calls as it sees and closes in on an insect, then zooming in and snagging the insect.

When feeding on insects in mid-flight, drongos use long, wire-like bristles at the base of the beak, to guide insects into the beak. The bristles are modified feathers.

Drongos have an incredibly varied repertoire of voice sounds, even within a species, and often imitate the calls of other bird species. Some species imitate calls of birds of prey, if disturbed at nesting sites, to scare off intruders. One call of the spangled drongo sounds metallic, resembling the plucking of a taut wire.

Drongos form monogamous (muh-NAH-guh-mus) mating pairs. Male and female contribute in building the nest, incubating the eggs (keeping them warm for hatching), and caring for the young. Nests are cup-shaped, and built with a hammock-style support, hanging from horizontal tree branches or forks. Monogamous pairs fiercely defend their territory, nest, and young. Other than those few facts, very little is known about other details of breeding behavior among drongos.

DRONGOS AND PEOPLE

There is little interaction between drongos and humans.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists two drongo species as Endangered, facing a very high risk of extinction, and four as Near Threatened, in danger of becoming threatened with extinction. Five of the six listed species live on small islands—Aldabra, Andamans, Comoros, Principe, and Mayotte— the sixth on a much larger island, Sumatra. The small islands have lost most of their original habitat, while Sumatra has lost half of its original habitat.

SQUARE-TAILED DRONGO (Dicrurus ludwigii): SPECIES ACCOUNTS

Physical characteristics: The body length is 7.5 inches (19 centimeters). No weights are recorded. The plumage of males is mostly black with a deep blue sheen, the tail has a small notch, the underwing bears white-tipped feathers. The bill is black, the eyes an intense red, black legs and feet. The female is colored similarly but the overall coloring is duller.

Geographic range: Square-tailed drongos live in Africa south of the Sahara.

Habitat: These birds are found in lowland and mountain tropical rainforest.

Diet: Square-tailed drongos eat mainly insects, also nectar.

Behavior and reproduction: Individuals forage alone, in pairs, and in association with other bird species that forage in flocks. It is often kleptoparasitic on other foraging birds. When foraging alone, a square-tailed drongo sits on a branch, waiting for an insect to fly within striking distance. When it does, the bird flies off the branch and snags the insect in mid-flight.

Square-tailed drongos have loud voices with many variations of sounds produced, generally a jumbled string of tweets, whistlings, and twangings. Like most drongo species, the square-tailed drongo can imitate the voices of other bird species.

Square-tailed drongos form monagamous breeding pairs, and both parents incubate the eggs and care for the young. The female lays two or three eggs. The nest is a small cuplike structure made of leaves, small twigs, plant fibers, spider webs and lichens. The nest is hung like a hammock from a tree branch.

Square-tailed drongos and people: There is little interaction between square-tailed drongos and people.

Conservation status: These birds are not threatened. ∎

GREATER RACKET-TAILED DRONGO (Dicrurus paradiseus): SPECIES ACCOUNTS

Physical characteristics: The body length is 13 inches (33 centimeters). The plumage is black all over with iridescent shades of blue on the upper wings. The head bears a crest of feathers that begins at the upper base of the beak. The eyes are bright red. The bill is gray. The tail is as long as the body, forked into two narrow, almost wire-like feathers, each of which flares into a rounded shape at the tip, thus the "racket-tail."

Geographic range: Greater racket-tailed drongos live in all of India, Sri Lanka, Andaman and Nicobar Islands, into Southeast Asia, including southwestern China, Hainan Island, Sumatra, Java, and Borneo.

Habitat: These drongos are found in tropical rainforest.

Diet: These birds eat insects, including moths, termites and dragonflies. Also lizards, small birds and nectar.

Behavior and reproduction: There is limited information. The species forms monogamous pairs, female and male sharing in incubating the clutch of up to three eggs, and feeding the young. The parents savagely defend the nest and young. The nest is cup-shaped and built in at the fork of a tree branch.

Greater racket-tailed drongos and people: There is no significant interaction between greater racket-tailed drongos and people.

Conservation status: These birds are not threatened. ∎

FOR MORE INFORMATION

Books:

Goodman, Steven M., and Jonathan P. Benstead. The Natural History of Madagascar. Chicago: University of Chicago Press, 2003.

Kavanagh, James. African Birds. Chandler, AZ: Waterford Press, 2001.

Morris, P., and F. Hawkins. Birds of Madagascar: A Photographic Guide. New Haven, CT: Yale University Press, 1998.

Pizzey, G., and F. Knight. Field Guide to the Birds of Australia. Sydney, Australia: Angus and Robertson, 1997.

Strange, Morten. Birds of Southeast Asia: A Photographic Guide to the Birds of Thailand, Malaysia, Singapore, the Philippines and Indonesia. London: New Holland, 1998.

Strange, Morten. A Photographic Guide to Birds of Malaysia and Singapore: Including Southeast Asia, the Philippines and Borneo. Singapore: Periplus, 2000.

Periodicals:

Duckworth, J. W. "Mobbing of a Drongo Cuckoo Surniculus lugubris." Ibis 139, no. 1 (1997): 190–192.

Herremans, M., and T. D. Herremans. "Social Foraging of the Forktailed Drongo Dicrurus adsimilis: Beater Effect of Kleptoparasitism?" Bird Behavior 12, nos. 1–2 (1997): 41–45.

Khacher, L. "Mimicry by Grey Drongo Dicrurus leucophaeus." Journal of the Bombay Natural History Society 94, no. 3 (1997): 569.

Manson, A. J. "Unusual Behaviour of Square-tailed Drongo." Honeyguide 114/115, no. 54 (1983).

Nair, M. V. "An Instance of Play Behaviour in Black Drongo Dicrurus adsimilis (Bechstein)." Journal of the Bombay Natural History Society 92, no. 2 (1995): 266.

Vernon, C. J. "Vocal Imitation by Southern African Birds." Ostrich 44, no. 1 (1973): 23–30

Web sites:

"MAGPIE-LARKS Grallinidae." CREAGRUS@Monterey Bay. http://www.montereybay.com/creagrus/magpie-larks.html (accessed on July 20, 2004).