Plantations, deforestation genetically affecting birds in Western Ghats

Continued fragmentation could lead to their extinction: study

From differing “songs” styles, to potentially lower adaptability against diseases, human forays into the forests of Western Ghats have led to genetic changes in the endemic birds in the region.

A study by researchers of the city-based National Centre for Biological Sciences (NCBS) has concluded that deforestation and commercial plantations of the Ghats over the past century have ended up forming small ‘islands’ for birds. The birds remain relatively isolated from their brethren in other islands, leading to genetic alterations.

Continued fragmentation could possibly lead to extinction of these species, warns the study published recently in the journal, Molecular Ecology.

The sample species chosen was the endemic Shortwing bird species.

The small birds prey on insects and are found only in shola forests (on the peaks of the mountains), and has a flight distance of less than a kilometre. However, with plantations having popped up all along the forests, the study finds that the bird populations have been confined in some cases to just 25 sq km of forest area.

“The genetic inflow has been noticeably reduced. Some populations separated by plantations have even developed different bird songs… in the future, these species will be more susceptible to diseases because of stagnating gene pool,” said V.V. Robin, one of the authors of the study. Researchers used blood samples from more than 215 individual birds from the Nilgiri biosphere – including Kodagu district – for genetic analysis.

Apart from the Shortwing species, other bird species such as the highly threatened Nilgiris Pipit and Laughing Thrush have also been severely isolated, said Mr. Robin.

Conservation

While similar isolation of elephants and tigers has received attention, leading to policies on creation of wildlife corridors and contiguous forests, Mr. Robin says there has been no attention on the smaller species. “There is little understanding of what birds require. An elephant corridor with eucalyptus trees will not be suited to these birds which require the closed canopy of natural forests,” he said. Uma Ramakrishnan, senior author of the study, believed that understanding fragmentation can aid in planning restoration to connect these isolated populations.

Original Post THE HINDU June 25 2015; By MOHIT M. RAO

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