Published: 19th October 2020
Call of the wild: Batman Rohit Chakravarty has made it possible for human ears to listen to bat calls. This is how he does it
This 29-year-old chiropterologist is currently pursuing his PhD in Berlin and before that, he was in Uttarakhand recording bat calls and programming it so that human ears could hear them
Most of the world is cursing bats today. No prizes for guessing why. But the fact of the matter is that these flying mammals have been the scapegoat for humanity since time immemorial. Whether for superstitious reasons, as many cultures consider these nocturnal creatures evil, or for being the reservoir hosts for emerging viruses, or not, we must remember that we have coexisted with bats forever. How many of us still live in apartments or homes beside which is a tall tree which bats call their home? We also forget that these creatures act as natural pest controllers, especially in cotton and rice fields and some species like fruit bats are excellent pollinators. To remind the world of the fascinating side of these creatures, chiropterologist Rohit Chakravarty has been up to something exciting — he makes the bats' ultrasonic calls, that are otherwise imperceptible to humans, audible!
He is listening keenly
Rohit has spent a lot of time in the pursuit of bats' calls. First, as a part of his Master's in Wildlife Biology and Conservation which he pursued from National Center For Biological Sciences (NCBS), Bengaluru, he took a trip to the Andaman Islands for another project. But when in 2015 he received an independent grant from UK-based Rufford Foundation, which offers funding to nature conservation projects from the developing world, the 29-year-old made his way to Uttarakhand. And since 2018, he has been a PhD student at Leibniz Institute for Zoo and Wildlife Research, Berlin, where he is currently based out of.
Blyth's horseshoe bat | (Pic: Rohit Chakravarty)
It was to sniff out Peters's tube-nosed bat that Rohit initially decided to visit Uttarakhand, the bat which was last sighted in the 1870s. "There was also the fact that no one was working on bats in that state," says the youngster. Hosted by Nature Science Initiative, Rohit set out to find bat haunts by asking the locals. "But unlike Andaman, where people are dependent on forests and have knowledge of bats and where to find them, people in Uttarakhand don't venture out in the dark as there are leopards and bears everywhere. Hence, we were on our own," he explains.
The process was that they would catch bats using nets, handle them using leather gloves and record their calls using a bat detector, which is an ultrasonic sound recorder. Then, he would use a bat sound analysis software in which he expands each note by ten times, "because otherwise, each original note is just about four to ten milliseconds long," explains Rohit. Expanding the calls also meant the frequency drops. So you are not just slowing down the tempo, but losing frequency too. The other way was through heterodyning. With the help of a software Rohit had programmed he could make bat calls audible by tuning into its frequency, just like a radio.
Now these calls synthesised from their recordings are not useful in identifying the species itself, so for scientific purposes, this particular aspect of Rohit's project might not be useful. "It is more for the general public, to help them understand how cool it would be if we could understand what bats sounds like," he explains.
Kashmir long-eared bat | (Pic: Rohit Chakravarty)
Let the beat drop
You have to check out Rohit's Instagram posts to hear the techno calls of horseshoe bat or Himalayan leaf-nosed bat which just sounds...absurd. In this way, he was able to capture calls of 32 species and track nine species for the first time like the somber bat (usually spotted in Western Himalayan region, last seen in Darjeeling in the 1970s) and long-tailed whiskered bat (usually spotted in China or parts of Central Asia). Another fascinating discovery was the Kashmiri long-eared bat which weighs ten grams yet dwells at a high elevation, almost 3,000 meters. "How does such a tiny bat live at such a high elevation, how do they manage with low oxygen levels," he asked himself.
This survey was actually the starting point for Rohit's PhD. He is now trying to understand the diversity of the different bats who live in different elevations in the context of climate change. “Why is it important? Because with climate change, things get warmer in the lower levels and some species will have to move up. Now, what happens to the species who are already at a higher elevation? The whole dynamics might change. Hence, to understand this, first we need to understand the diversity of species at different levels, what do they eat and all of that," he explains.
The long-term plan for Rohit is making bats popular in people's minds, for all the right reasons. And making bat calls audible was just the first step. This Nagpur-born youngster's fascination with bats began because as a child, he spotted a fruit bat flying right into his house and since then, he has realised how neglected these smaller species are in India when compared to the conservation steps carried out for tigers, elephants and others. "For so many years, bats have been living close to humans, but every time a disease breaks out, we all panic," he points out. Except for two species of bats, the other 126 of the 128 species of bat in India are not protected. He would really like to see better protection for bats.
For more on him, check out instagram.com/paintedbat