Papiya Bhattacharya takes a close look at a study by V V Robin, fellow at NCBS, and his colleagues Pooja Gupta, Prachi Thatte and Uma Ramakrishnan (faculty at NCBS) on the shortwings and laughing thrushes on what threatens the existence of these birds of the western ghats
Islands in the Sky
Sholas are geographically areas isolated on high elevations, thus forming a ‘sky-island’ system.
● The study shows that natural barriers such as the Chaliyar Valley, Palghat Gap and the Shenkottah Gap show up as breaks in
population connectivity of these species
● The populations on either side of the gap were genetically different from each other. For eg: To the north of the Palghat Gap are the rufous-bellied shortwings and to the south are the white-bellied shortwings.
● On top of this, human-fragmented forests also showed genetic signatures of recent isolation. This suggests that fragmentation is hindering the birds’ movements across human habitats like plantations.
What are Shortwings?
They are small insectivorous birds that live in the Shola Forests in high elevation areas of the Western Ghats. They are about the size of a sparrow and are found nowhere else in the world.
What Puts Them at Added Risk
- Robin explains that birds that live on isolated mountain tops or sky islands in southern Western Ghats such as the south of Coorg in Kodaikanal, Munnar and Ooty till Thiruvananthapuram have populations that are naturally fragmented due to valleys as their habitats occur in patchy patterns.
- Due to human habitations, forest patches on these habitations have become further fragmented.
Used advanced genetic analyses and computer simulations to find the effect of patchiness on the movement of bird population across forest fragments
The researchers sampled all the known populations of the two species of Shortwings across the Western Ghats, with blood samples from 218 individuals.
The DNA from these samples was then used to explore the genetic patterns of the bird populations in the Western Ghats.
The patterns from genetic analyses were confirmed by simulations.
The genetic analyses and computer simulation approaches used in this study add a whole new aspect to conservation biology.
The large amount of genetic data and analyses helped us to gather key information on the species biology and vulnerability of Shortwings towards fragmentation. This would have been very difficult to attain from a purely field based ecological study,”
—Pooja Gupta, an equal first author of the study.
“Computer simulations, although not commonly used in conservation biology research, are excellent tools for understanding complex evolutionary processes and can substantiate the inference drawn from the field data”
—Prachi Thatte, another author of the study.
Understanding how different species are affected by fragmentation can help us plan their conservation. Thinking ahead, can we plan habitat restoration efforts?
—Dr Uma Ramakrishnan, senior author of the study