Kerala’s avian diversity gets richer

The newly accepted banasura laughingthrush has a restricted distribution in Wayanad district.

The newly accepted banasura laughingthrush has a restricted distribution in Wayanad district.   | Photo Credit: Sandeep Das

The avian species diversity of Kerala got a boost in the last days of 2016 with BirdLife International dividing a species in two. BirdLife International, an organisation which assesses the conservation status of birds globally, has split the group of montane laughingthrushes, which are endemic to the Western Ghats, and recognised them as two new species. As a result, Kerala now has four mountain laughingthrushes in place of two.

The newly accepted species are Banasura laughingthrush (Trochalopteron jerdoni), which has a very restricted distribution in Wayanad district and Travancore laughingthrush (Trochalopteron merdionale) found in Thiruvananthapuram district. While the conservation status of the Banasura species was assessed as endangered, the Travancore variety was considered vulnerable, considering the risk the species were facing.

The two original species of the family were Nilgiri laughingthrush and Palani laughingthrush. The Nilgiri species, assessed as an endangered one, is found in Silent Valley National Park and Siruvani hills of Kerala. The near-threatened Palani laughingthrush is found mainly in Munnar hills and the mountains of Periyar Tiger Reserve apart from Grass Hills and Palani hills in Tamil Nadu, according to ornithologists.

Dr. P.O. Nameer, Head, Wildlife Division of the Kerala Agriculture University, and J. Praveen, the coordinator of Bird Count India, which organises the national bird counting exercise, had been arguing for treating the Banasura and Travancore species as separate ones, considering how different they were from the other two. They had published a paper in 2012 making a strong case for splitting the species.

According to Dr. Nameer, colonial ornithologists had suggested way back in 1800s that all four laughingthrushes be treated as independent species. However, in the early 1900s, the concept of sub-species gained currency and two of them were wrongly treated as sub-species. It was in 2012 that a scientific assessment was carried out to establish the existence of four different species, he explained.

The identification of the two new species was carried out by following the internationally accepted scoring system. The morphological differences, the distribution of each species, its habitat and altitude preferences were identified through field trips. The scores obtained were sufficient to separately classify the species. The conservation status of the birds was also revisited after their reclassification, he said.

BirdLife International recognised the findings and reclassified the birds in the latest Red List. Research papers on the genetic characteristics of each species are expected shortly, he said.

Laughingthrushes are found only in the peaks of Western Ghats, popularly known as sky islands. These mountain peaks are separated from the others so well that the birds from one sky island find difficult to move to the next sky island. This has resulted in the creation of four closely related species, each of them occupying a series of mountain tops across the entire range of southern Western Ghats, noted the ornithologists in a scientific paper.

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Printable version | May 25, 2020 8:11:16 PM |

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