The science of birdsong

Conventional post-disaster analyzes often fail to capture the impact that natural disasters have even on human beings. No wonder, the focus seldom falls on wildlife as such studies are mainly done only on utilitarian grounds. For the first time in the country, an eco-acoustic study carried out by a PhD scholar in Thattekkad Bird Sanctuary has revealed how the avian biodiversity has suffered and survived the 2018 floods.

The study by Sajeev C Rajan as part of his research work at the School of Informatics, Kerala University of Digital Sciences Innovation and Technology, has found that the avian life in the bird sanctuary has almost recovered from the impact of floods within one year.

“I had started recording birds’ sounds in the Thattekkad sanctuary and two other places well before the 2018 floods. Since I recorded the soundscape before, during, and after the floods, it came in handy for analyzing the flood toll on birds,” said Sajeev.

As per the data, the presence of avian life and its complexity came down by 50% during the floods in the month of August and it tumbled down further thereafter. The soundscape analysis showed that the sanctuary almost regained the pre-flood biodiversity by December 2019 without any human intervention.

The Thattekkad sanctuary is home to 284 bird species, of which three are vulnerable, eight nearly threatened, and 11 endemic. In addition, it provides seasonal refuge to 72 migratory avian species.

During the same period, Sajeev had undertaken a similar eco-acoustic study at Iringol kavu (Iringol sacred grove) some 30km from the Thattekkad sanctuary. “The analy-sis of soundscape data collected from the sacred grove proved that the Kavu, spread across 20 hectares, suffered not much from the floods and biodiversity remained almost the same during, before, and after the floods,” Sajeev pointed out.

Unlike Thattekkad, a low-lying area that remained submerged under three feet of water for more than 15 days, Iringol Kavu is situated in an elevated position. The study mentioned this as the major reason for the differences in flood impact on the two regions with comparable floristic compositions. Eco-acoustics is an emerging interdisciplinary domain that engages in data-driven analysis of biodiversity by approaching every landscape under observation as different soundscapes. Powerful recording devices that are double the size of police wireless sets are used for capturing the soundscapes. It can record audible sounds in nearly a 500m radius. Eco-acoustics hinges on the analytical study of recorded biophony collected at intervals and is a part of ecological informatics, another major emerging interdisciplinary area.

Bio-diversity analysis using ecoacoustic tools is comparatively cost-effective and highly accurate. Moreover, it can produce quicker analysis using computational data. Though Sajeev is also trying to explore the possibility of extending the methodology for the species-wise study of birds, the applicability of ecoacoustic remains mostly in identifying and analyzing biophony in large areas and comparing the data collected in different intervals to assess the overall impact on biodiversity at specific time points. “Only computational data analysis can show the way ahead for biodiversity conservation and fastpaced large-scale studies.” Eco-acoustics is an interdisciplinary area that promises huge benefits in terms of quick bio-diversity analysis. The practice of making bio-diversity analysis by way of producing descriptive reports can no longer be of use when we are faced with new ecological challenges of colossal magnitudes,” says Dr Jayashankar R Nair, head of CV Raman Laboratory of Ecological Informatics, University of Digital Sciences.

According to Jayashankar, ecological informatics and eco-acoustics can be of great use to a state like Kerala that is witnessing natural disasters frequently. It could also be of use for bio-diversity studies in connection with development projects that are feared to impact the ecology badly, he said.

However, the Covid-19 outbreak has put an end to the soundscape recordings in Thattekkad and Iringol kavu. Since data is key, only sustained intervention for data collection from ecologically fragile and biodiversity-rich areas at regular intervals can push forward the cause of data-driven bio-diversity studies.



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Views expressed above are the author’s own.



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