The amazing mimicry of the drongo

It’s a frog! It’s a squirrel! It’s a drongo - ALL - The Hindu



The racket-tailed drongos are great mimics and make good use of the skill



Samira Agnihotri can take you to the exact spot where she had her mind blown more than a decade ago. As a postgraduate student of wildlife biology, she was recording birdsong at BRT Wildlife Sanctuary in Karnataka when a greater racket-tailed drongo, sitting on a tree stump, mimicked the call of a crested serpent eagle, before switching seamlessly to a flameback woodpecker and then a jungle babbler. As the impressed researcher watched the dove-sized copycat, her Soliga field assistant, Madha, commented, “You should do your Ph.D on this bird since it is doing a Ph.D on all the other birds.”



Little did she realise then that was the course her career would take. The drongo’s performance became the focus of not just her Ph.D but her postdoctoral as well.



Agnihotri was bird crazy since she was a three-year-old watching an ashy prinia nest in her family’s backyard in Vadodara. The eggs were blood red, she recalled. Love of the outdoors ran in her family as they vacationed in wild places every year. Her great grandfather wrote a book on Indian wildlife in Hindi. One of the first books she read was Salim Ali’s The Book of Indian Birds . Ali writes that the racket-tailed drongo in flight with its long tail feathers streaming behind it gives “the illusion of the bird being pursued by a pair of large bumble bees.”



Tailored calls



Over the course of 15 years, Agnihotri recorded racket-tailed drongos imitating nearly 40 species of birds, two mammals, two frogs and even an insect. This extensive repertoire doesn’t mean they learn every sound they hear and reproduce it for no reason at all. Instead, they tailor their calls to regale their audience. They impress potential mates with the breadth and complexity of their performance.



However, drongos don’t restrict mimicry to their breeding season alone. They make good use of this skill to fill their stomachs. Racket-tailed drongos join hunting parties of babblers, bulbuls, and warblers. They let the others hop around and flip leaves while they sit on a high perch and keep a sharp eye. When insects stirred up by the hard-working hunters fly out, they snatch them.



The drongos don’t hobnob only with other birds. Some mimic bonnet macaques which Agnihotri thinks startles the primates to move and rouse up insects. The Soliga declare the dodda karali , as they call the racket-tailed drongo, the laziest birds they have seen.



Instead of physical labour, the racket-tailed drongos invest in vocal artistry. They mimic the calls of species with whom they hang out. If they want to join a flock of jungle babblers, they imitate those grating cries. When consorting with woodpeckers, they twitter like them.



As sentinels, the drongos impersonate the agitated calls of other species, as if alerting them of an approaching predator in their language spreads the message better. This rallies the entire mob to drive the menace away or flee from it. They amplify others’ warnings too. When giant squirrels warn of a raptor flying over the canopy, the racket-tailed drongos copy the mammals’ toy gun-like rattle. Why mimic squirrels instead of sounding their own alarm calls remains an unsolved mystery, says Agnihotri.



Recognising this role, the Soliga also call the species, kolu kaara (stick-bearer) or ‘policeman of the birds’. They liken them to an elder who maintains peace and order within the community. For performing this duty, the Soliga say, the other birds offer a feather each to the drongo.



Upper hand



Drongos also scare the daylights out of small predators, such as crows, by imitating eagles. Matching calls to the correct species is a remarkable feat, but they also seem to know who has the upper hand over them.



Agnihotri’s field assistants have climbed up trees with drongo nests to ring the legs of nestlings with coloured bands. Once the chicks become adults, they will be easier to recognise as individuals. Some drongo parents were baffled by the tree climbers. Agnihotri watched as the anxious birds sought to chase the Soliga as they would a predator. They mimicked the calls of scimitar babblers. When that didn’t scare the humans, they chose the cries of large animals such as bonnet macaques and giant squirrels. That failed too, and they resorted to eagle shrieks. “They tried everything,” Agnihotri says. “But they didn’t know what would scare the men.”



Despite their ability to fool others, the drongos are not above petty thievery. When other birds have a morsel that one covets, it swoops at them while screaming aggressively. It may throw in some imitations too. The scared bird drops its prey which the drongo grabs. The skill that delivers supper here is not mimicry but straightforward bullying. But Agnihotri is as impressed by the drongo’s intelligence which makes the phrase ‘bird brain’ sound like a compliment.



Agnihotri recorded racket-tailed drongos imitating nearly 40 species of birds, two mammals, two frogs and even an insect