By Kadambari Deshpande
As I travelled along the Agasthyamala hill ranges of the southern Western Ghats of Kerala, the undulating, verdant green terrain, the escarpments, the peaks and the valleys, narrated their biogeographic sagas. Here, in an upstream catchment of the Kallada River, the forest types range from evergreen forests – dotted with trees like Chenkurinji (Gluta travancorica), to moist deciduous forests, to Myristica swamps with their prehistoric knee-roots, bamboo brakes, and Ochlandra reed-patches. Nearly all of the lowland evergreen forests, once extending up to 50 msl, have now been replaced by uniform sheaths of rubber plantations, along with some oil palm – visible even in satellite images. I could see that though rubber was no forest, it did add some green shades to the landscape. This geographical setting excited me. I was convinced that it would be perfect to conduct my fieldwork on bat diversity and distribution in the diverse land-cover types that made this mosaic.
My study involved surveying bats both inside and outside a wildlife sanctuary, a protected area that was notified many years ago to help preserve this stunning forest. With my funding secured by a small grant, I was all set to explore bat communities and know how they used this collage of a landscape. My approach was to listen to the ‘voices’ of bats using non-invasive acoustic methods to record their ultrasonic calls.
Insectivorous bats echolocate with their species-specific call signatures. Most species roost in dark, cool places such as caves, rock crevices, or tree hollows. For my study, I wanted to compare how the diversity of bats differed between forests and other habitats. With no baseline information available, I would first visit roosts and record species calls. Later at night I would choose locations across different land-uses and record bat activity patterns while they foraged. In the forests, I would be all-ears for forest-specialist bat species, which had peculiar call signatures that they used to glean tiny insects from dense vegetation.
Fieldwork at night had its own wonders and dangers. Within the protected area, they mostly came in the form of encounters with elephants, pit vipers, or sloth bears. My fieldwork was made possible by the extremely helpful forest department staff. They helped me find roosts, and in capturing bats (if needed for species confirmation). They also kept an eye out for signs of an elephant clan nearby, or a zombie sloth-bear, or a marching sounder of wild pigs. On pitch dark nights, occasional glimpses of flying-squirrels gliding between tall trees, distant barks of muntjacs in the mountains, and sudden, swift, passes of mouse-deer were precious experiences. The forest, even at night, was assuring, peaceful, and with a comforting silence. This mood would be elevated occasionally by the voice of a rare bat which I listened to with the help of an ultrasound detector. The three months that I spent inside the forest were merry, and I was by now armed with some rich information. It was time to replicate this work outside the protected area, in a more unpredictable landscape.
The dwellings of bats inside the protected forests were “typical” roosts such as remote caves. Outside, however, there was a range of places they used, including rocky outgrowths, abandoned houses, room attics, railway tunnels and closed canals. I began visiting all possible rock formations and abandoned houses to check for the presence of roosting bats. For this I would go around during the day in Shivanna’s or Renu chechi’s auto-rickshaw. These trips would help me save money so that I could hire Shiju’s jeep in the evenings for accessing places that were further away and in difficult terrain. Crawling through narrow rock crevices, and walking in tunnels with waist-deep water, I had by now collected data on more than 20 species of bats, and possibly had the first recordings of their call signatures from this landscape.
Contrary to my expectations, the task of sampling bats was much more difficult outside the protected area. Despite the presence of bats, many roosts could not be accessed. The cool, dark places that I was exploring for bats also harboured many dark realities of human habitation. I once narrowly escaped getting caught in a thin line trap that was set out for porcupines at the mouth of a rock-cave. In another instance, the sight of open syringe-needles scattered on the floor of an abandoned house traumatized me. Broken alcohol bottles with a strong stench of spirit lay in and around such bat roosts, and encountering a drunkard in somewhat desolate locations on the way, was slowly turning customary. After the daylong tiring work, where even known roosts would become inaccessible, completely silent nights (without bat sounds) would follow. I considered even such silent nights meaningful, as they indicated very low or no bat activity in some habitats. Desperate for some animal sightings, on the way back late at night, I would set my hand torches ready, but to no avail. There was hardly any wildlife left to be encountered. As a cumulative effect of all the above factors, it started getting increasingly difficult to find sustained field assistance for the “uncool” work I was doing. The contrast between my days inside and outside the protected area just grew sharper. It was not that bat communities were absent outside, but the experiences I had while encountering them unravelled some stark realities to me.
This article is the first in a two part series. Please click here to go to the second part.
The author dedicates this article to the memory of the Late Mr. Syed, and his family, for their help and support.
About the author:
Kadambari Deshpande is a PhD student at ATREE and has been studying the ecology of bats in the Western Ghats. She is keenly interested in the sensory ecology of animals and relies on acoustic methods for much of her work. She has also been studying the perceptions of people about bats to understand the importance of local knowledge for bat conservation.