Birds are excellent mimics. They are also commanding tricksters who can put the Lannisters to shame shame. Reporter Udipto Phukan tells us why there’s more to birds than chirp and merry.
There are places in Bangalore, unlike many other metro cities, where one can observe and listen to a multitude of birds. The city has an active birdwatching community which makes morning visits to Lalbagh and Cubbon Park to spot these aves.
Many of these activities are planned bearing in mind the month and migratory seasons. Although we hear them every day, we don’t generally pay attention to the different sounds that birds make or when and why they make them.
Dr Samira Agnihotri has spent close to 13 years of her life trying to find some answers. An event aptly titled ‘What’s that racket? Linguists of the bird world’ was hosted by Urban Solace café on Saturday evening. The talk was the eighth instalment of the bi-monthly series ‘Cafe Oikos’ which brings together various researchers on Ecology and Conservation, and their discoveries.
Although the Facebook event page mentioned seats for only 40 attendees, the venue saw close to 60 curious faces fighting for space inside the cramped room. Many resorted to standing near the door and sitting on the floor. Dr Samira holds a Master’s degree from NCBS and since then has spent a lot of time in the forests of Biligiri Rangan Hills, trying to record and understand vocal mimicry in birds. This eventually shaped her doctoral thesis which she obtained from IISc, Bangalore.
She brought in audio and video recordings of her work showing us the ways in which birds mimic according to different species. The high pitched chirps, tweets and whistles by the Bandit Bay Cuckoo and the Fairy-bluebird resonated in the room. Needless to say, their contribution to nature’s orchestra is an absolute delight to hear, even in a recording.
In India, we have species like the Hill Mynah, Orange Headed Thrush and the Racket-tailed Drongo which are popular mimics.
Dr Agnihotri’s focus is on the Racket-tailed Drongo, a species which is found abundantly across the country.
But how do we identify the mimicry from the natural calls?
The simplest way to identify mimicry, according to Dr Agnihotri is to observe the spectrograms.
A Spectrogram is a visual representation of a sound wave that simultaneously tracks two kinds of sounds. The sound produced by a bird and the sound produced out of mimicry by another bird. Similarities between the two help in determining whether there is mimicry happening.
According to Dr Agnihotri, one of the reasons why birds mimic is to attract potential mates. Lyrebirds from Australia are amusing in this regard because they not only mimic but also dance. They match certain sounds with certain steps to create a kind of choreography.
This striking ability to perform increases the chances of attracting a mate. Dr Agnihotri played a video of a Lyrebird doing the mimicry and dance which left the audience wide-eyed.
In the video, the bird was mimicking around ten different Australian species while creating a dance pattern which involved lifting its tail up and down, flapping its black and white wings and performing jumps and deep bobs.
All of it was completely in sync with the chirping that it was producing. Research says that the female Lyrebird looks out for the male species which can do the this choreography with great flair and innovation.
When Winter Comes
Another reason why birds mimic is for deception. Dr Agnihotri showed a video of the Fork-tailed Drongo in the Kalahari Desert which mimics warning calls of Meerkats, (animals belonging to the Mongoose family). It does this mostly in the winters when food is scarce.
The Drongo’s fake warning calls startle the Meerkats who begin looking for food. When the Meerkat has found its prey and attacked it, the Drongo swoops in, claims the prey, and flies away with it – leaving the Meerkat hangry. Not too different from interns doing all the leg work and editors swooping in to claim by-lines.
There is a reason why David Attenborough calls the Drongo ‘the greatest trickster of the Kalahari’.
Watch this superb video to see the frenemy between Drongos and Meerkats.
Throughout her work in the BR Hills, Dr Agnihotri has seen the Racket-tailed Drongo mimic 40 bird species, 3 mammals, 2 frogs and one insect. It has a large repertoire of its own calls as well which finds its way into the mimicry that it creates.
“I need to be very familiar with the calls of other species. I must have recordings of all the other species so that I have a spectrogram which I can use to do match-making with,” Dr Agnihotri says -indicating the amount of work one has to put in.
Other interesting aspects of the Racket-tailed Drongo are the ways in which they mimic. The first is a sequence of repetitive mimicries – one constant sound produced repeatedly. The other is a sequence of non-repetitive mimicries.
Dr Agnihotri made a startling discovery when she conducted a couple of playback experiments. She played recordings of a Drongo to see the bird’s response.
“The repetitive mimicry only attracted other Drongos. It approached the speaker and responded to what was playing. But the non-repetitive mimicry attracted birds of other species. They responded as if they were communicating with members of their own species”
“Every flight begins with a fall.”
― George R.R. Martin, A Game of Thrones
This shows why the Drongo is an active participant in mixed hunting parties where there are numerous other birds. Research shows that calls like the begging calls (made by Cuckoo Chicks to procure food from the host mother) are coded genetically. But the rest is learnt from parents and neighbours as they grow up.
The audience had a lot of questions to ask after the session. Ranging from whether the Drongo mates with the ones it mimics, whether their mimicry gets affected by age, and the ethics of playback experiments – which is a matter of concern considering the fact that everyone can do it with their smartphones which, as we all know, has harmful effects on the birds.
The one lesson to have emerged from the session is that we have such fascinating species in our midst. But it’s a shame that their sounds are lost to us in the noise of the everyday.
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