Illustration: Rohan Chakravarty, www.greenhumour.com
New study shows that bats prefer rainforest fragments, riverine habitats and shade-grown coffee to tea plantations in the Valparai Plateau.
The Western Ghats in India is the most densely populated biodiversity hotspot in the world! A mere six per cent of its old-growth forests remain; most of its natural vegetation has been lost to agriculture, monoculture plantations and other developmental projects such as dams and mines.
As the human population burgeons and agriculture intensifies, biodiversity faces increasing pressures. Old-growth forests are irreplaceable for wildlife. However, even in agriculture-dominated landscapes like the Valparai Plateau that lies in the southern Western Ghats, wildlife-friendly plantations and sprinkled forest fragments can serve as refuges for bats and other wildlife.
In the first-ever study of bats in tea plantations, researchers from the University of Leeds, the National Centre for Biological Sciences (NCBS) and the Nature Conservation Foundation (NCF) surveyed 10 species of insectivorous bats in the Valparai Plateau for three years. The bats were located by a combination of recorded calls and capture, and the data was then used to map where suitable habitat for each species could be found in the region, and if each of these had any preferences of habitat.
Researches of this study found a good diversity of bats in areas along rivers (including tea plantations), especially if there were native forest trees along the banks. These riverine habitats are important ecosystems for many bats as they provide water to drink, insect food and varied plant resources.
Even rivers running through tea, particularly if they are lined with native vegetation, make for good bat habitat. Credit: Claire Wordley
At least six bat species were recorded even in a tiny 2.2-hectare forest fragment! An incredibly encouraging finding for NCF’s conservation efforts in the area, which have focussed on restoring degraded forest fragments.
Even though surrounded by tea or other monoculture plantations, forest fragments and rivers with natural vegetation cover hosted many bat species. Certain coffee plantations, too, were almost as attractive to bats as forest fragments, while most of them avoided large and heavily modified tea plantations.
And the reason for this? These coffee plantations are grown under a canopy of native forest trees—with roosting sites and insect food aplenty! In short, they have the ingredients of good bat habitat.
Coffee plantations grown under the shade of native forest trees were almost as attractive to bats as forest fragments. Credit: T. R. Shankar Raman
While it’s great news that these bats are surviving in coffee grown under native trees, forest fragments and riverine habitats in the region, further deforestation could be a major threat to them.
Two of the bat species studied—the lesser false vampire bat and the lesser woolly horseshoe bat—are especially vulnerable as they are adapted to life in the forest. They weren’t found in tea plantations at all! Loss of forest fragments and decline in wildlife-friendly plantations could put them at great risk, researchers say.
The lesser false vampire bat (above) and lesser woolly horseshoe bat are forest-dependent and were not found in tea plantations. These vulnerable species could face declines if forest fragments are destroyed further. Credit: Nithin Divakar
As more and more forests are being cleared for agriculture, it is imperative to understand the potential of varied agricultural landscapes to support biodiversity. For wildlife and humans to co-exist in times like these, we must ensure that wildlife-friendly agricultural practices are made more widespread.
Bats play an important role in controlling pests, and tea plantations that harbour the ingredients of good bat habitat can be beneficial not just to bats. The study recommends that plantations in ecologically important areas like the Western Ghats should retain and restore forest fragments and riverine corridors, and have native shade trees instead of exotic ones to support a greater diversity of bats and potentially other wildlife as well.
The study was published recently in the journal Biological Conservation and can be accessed here.
- Claire F.R. Wordley, Mahesh Sankaran, Divya Mudappa, John D. Altringham (2015) Landscape scale habitat suitability modelling of bats in the Western Ghats of India: Bats like something in their tea. Biological Conservation 191 (2015) 529–536.