It is not just thousand-year-old deities that dwell in the ancient temples of southern Tamil Nadu. Bats too make their home in the little nooks and high ceilings that these stone structures offer. However, temple renovations could be lowering bat numbers in these sacred spaces, suggests a preliminary, yet-to-be-published survey.
The sight of bats inside some temples in Tirunelveli district piqued the interest of T. Ganesh (Senior Fellow, Ashoka Trust for Research in Ecology and the Environment; ATREE) and his students. How many bat species dwell in these temples and what makes them suitable bat homes?
The team, which began studying these bats since 2011, visited 22 temples across three towns (Kallidaikurichi, Ambasamudram, Alwarkurichi) in May 2018. They found 37 bat roost sites of seven species (including the Leschenault’s rousette Rousettus leschenaultii and the Lesser mouse-tailed bat Rhinopoma hardwickii ) in 18 temples. They also noted temperature, humidity, light and noise at these roost sites; basic analyses show that higher roost height and a combination of both noise and low light played a crucial role in bats selecting specific roost sites.
The team also noticed that temple authorities used several methods to prevent the mammals from roosting: they blocked bat entrances using nets and logs, filled up existing cracks, added lights, reconstructed temple towers and painted the old dark stones white. Six temples implemented some of these renovations in the later half of 2014.
The numbers of Schneider's leaf-nosed bat (Hipposideros speoris) dropped from 211 in May 2014 to 26 this year. However, a more detailed and robust study would be required to understand this better, says Chetan Misher, one of the research students at ATREE who conducted the study.
Temple renovation is indeed a main cause of disturbance to bats, according to D. Paramanantha Swami Doss (assistant professor at St. John's College, Payalamkottai), whose team has also been studying these temple bats for the last 15 years. Bat diversity could also be decreasing here, he adds.
“We recorded a [member of] Tadarida species [free-tailed bats] for the first time in Tirunelveli district from the Brahmadesam temple, but when I went there a few days ago, there were none left,” he added.
While Dr. Doss hopes to focus on bat awareness sessions for local residents, Dr. Ganesh and his team hope to provide bat houses outside temples that the bats could use if renovations drive them out of their holy roosts.