Colours of Wildlife: Forktailed Drongo

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Forktailed Drongo

Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"


Today's painting is a Forktailed Drongo, Dicrurus adsimilis. I promised to speak about this bird a while ago when I wrote the entry on the African Cuckoo. The Forktailed Drongo is the only currently known host of this cuckoo (meaning the cuckoo lays its eggs in the drongos' nest, who unwittingly raise the little cuckoo chick instead of their own).


Drongos are a group of birds that occur mainly in Africa and Asia. The word 'drongo' comes from a Malagasy name for one species, but is now applied to the entire family. Like the Scops Owls they have proven to be good at crossing stretches of ocean, having colonized the Indonesian Islands, New Guinea and Australia from Asia, and Aldabra, the Comoros and Madagascar which are closer to Africa but (some of which?) might actually have been colonized from the Asian side as well. They, too, have evolved into different species and subspecies on different islands. Though most species occur in the tropics, there are some that have spread northward to Iran and Siberia in Asia.


There are five currently recognized drongo species in Africa. Of these the forktailed drongo is the one most people encounter. It is a bold, conspicuous bird, hunting in open savannah regions all over sub–Saharan Africa. Drongos are excellent fliers. They use their forked tails much like swallows do, spreading and flexing them to help them execute rapid twists and turns in mid–air. They also have long, elegantly pointed wings, and their mode of flight is very light and seemingly effortless. Contrasting with the long wings and tails, they have short legs and feet. Drongos hunt mostly flying insects. They will sit on a perch, spying out the environs, and swoop out at promising prey items. If successful, they return to the perch and beat the insect against it, killing it and also expelling its entrails and/or rubbing off its stinging hairs. Larger items might be held down in the claws and dismembered by the bill. This attachment to an open perch site makes them very easy to see and photograph. It is rewarding to watch them for a while, marveling at their fast and expert aerial maneuvers.


They are also quite noisy. Drongos have harsh, raspy voices, emitting a variety of different shrill screeches. These loudly proclaim their lordship and authority over their territories. They will sometimes mimic the calls of predatory birds – most particularly the Pearl–Spotted Owlet. Some drongo species even mimic mammalian predators like cats. But they will also mob larger predatory birds or animals. In Australia the word 'drongo' has come to be a slang term for 'idiot' for the seeming foolishness of drongos in attacking these large and dangerous creatures. But they use their flying speed and skill to aid them in this. They will first fly up and then swoop at the predator in a high–velocity, gravity assisted dive. In India drongos are sometimes called 'king crows' for their behaviour of fearlessly driving away the much larger crows. Smaller birds take advantage of this. They build their nest near those of drongos, trusting in the drongo security system!


A drongo's perch functions as the 'marker' and centre of its territory. But they sometimes hunt in a different way – by actively searching rather than sitting in one place. They will join, and often be the defining constituents of, the 'bird parties' that bring joy to every bird watcher's heart on being encountered. Bird parties consist of several different bird species, that form a large 'hunting party' that systematically makes its way through a tract of savannah or forest. The party will include birds focusing on different prey items and using different hunting strategies, so that insects that escape from one are likely to be caught by another. When joining such a party, drongos will put aside their aggression and "I work alone" attitude and allow two or three other drongos, apart from other bird species, to hunt with them.


Another kind of cooperative behaviour is associating with large mammals, especially cattle or large antelope. Keeping close to these large grazers, drongos will look out for and try to catch insects that jump or fly to escape being trampled. Drongos might occasionally use the backs of the beasts as perches.


Other drongo species in Africa all live in forests, making them harder to see. In Asia as well, most species are rainforest dwellers, only a few hunting in more open habitats. The group probably originated in Asia, spreading to Africa about 15 million years ago, and to Australia about 6 million years ago. Most drongos are black, with varying degrees of glossiness, but some are grey, and others have white bellies. The forktailed drongo is fairly typical in appearance, but some drongos lack the forked tail, while others exaggerate it, with splayed or recurved tail tips, and in a few species there are extensions to the tail feathers in the form of long streamers, consisting of bare shafts with paddle– or racquet–like tips. A few drongo species have crests on their heads as well. In some parts of the world drongos are tamed and trained to catch small pieces of meat thrown into the air.


Forktailed drongo nests are shallow, flimsy cups made from twigs and roots, bound together with cobwebs and placed in the fork of a tree branch. Their eggs vary a lot in appearance, with white through cream to pink as the ground colour, with speckling in a variety of colours. As I said in the cuckoo entry, this egg variability makes it easier for a drongo mom to pick out the eggs of a cuckoo laid in her nest. . . but the cuckoos have evolved to produce different kinds of eggs as well, and a female cuckoo will specifically seek out a drongo nest with eggs that look like her own. This is now a kind of evolutionary arms race, producing matching variations in both species. Cuckoo parasitism doesn't seem to have much of a negative impact. Drongos remain very abundant, while the cuckoo is rare enough that I haven't seen one yet.


Despite the abundance, conspicuousness and familiarity of forktailed drongos (not to mention the other rarer drongo species) they are surprisingly poorly known. Much of their behaviour, such as courtship, has not yet been intensively studied. This is a golden opportunity because even casual birdwatchers might glimpse something that turns out to be new to science.

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