Frog song and climate science

Frog song and climate science

Dr R. Ganesan, Seshadri, and Dr S.D Biju

Frog song and climate science

Shown here, work station high up.
Photo credit: K. S. Seshadri

‘Counting epiphytes high up in the tree tops, we were racing against the lowering clouds from the west. Working at 100 feet off the ground is tricky business, not helped if it rains, and July is the season for rains. As it happened, it put us at the right place at the right time for explorations in an unexpected dimension.’ KS Seshadri does canopy research with Dr T Ganesh, Dr S Devy and their team in Agasthyamalai, and in the course of getting drenched high up in the branches in the waning light, he re-discovered that frogs sing in the rain. Only, this frog song was up in the canopy, not on the ground.

Intrigued by the cacophony of sound that the rains triggered, Seshadri and his team initiated a monitoring programme to document the presence, or absence, of amphibians in the Kakachi- Kodayar region of Kalakad Mundanthurai Tiger Reserve (KMTR), paying special attention to canopy frogs. The study aims to document anurans, their calls and habitat, in the canopy or on the ground, and will be the first effort to monitor amphibians for long term population dynamics based on calls. Since frogs and toads respond to changes in atmospheric moisture and temperature, the team reasoned that an analysis of sound recordings, combined with readings from climate data loggers, could help improve understanding of the effect of climate change on amphibian populations. This is the second objective of the research project.

Duttaphrynus beddomei (Beddome’s toad)

Calacad gliding frog, Rhacophorous calcadensis

Raorchestes bobingeri– Bob Ingers bush frog

The team has collected data during the South West as well as North East monsoons, using sound recorders and data loggers placed on the canopy as well as on the forest floor. The monitoring of calls was accompanied by manual night-time searches to match the singer to the song. As of now the team has matched eight species of anurans to their mating calls, of which two may be canopy dwellers that have come under scientific scrutiny before. The team had the rare privilege of sighting the reclusive Duttaphrynus beddomei(Beddome’s toad), last seen a decade ago in 2001. Dr R. Ganesan, Seshadri of ATREE and Dr S.D Biju of Delhi University rediscovered the Chalazodes bubble nest frog, Raorchestes chalazodes, last documented 136 years ago. Not much is known about this frog. They even found the Calacad gliding frog, Rhacophorous calcadensis, on trees, over 32 metres high in the canopy. It was later observed to come down to the ground for breeding, where it deposited spawn in clumps of frothy foam on vegetation overhanging streams. Tadpoles, when they emerged, could simply drop into the water. Another intriguing find was the Raorchestes bobingeri– Bob Ingers bush frog. For over a year, the team kept hearing its call without being able to locate it. One night, Chian, field assistant with the team, abandoned the security of the rope and climbed to the topmost branches, where this frog, half the size of a human thumb, was finally captured on camera. Other species that the team found are still being identified.

The team will share methodology and protocol for monitoring through a paper to be published soon. The team has invested in climate data loggers and sound recording equipment that can be preset to wake up and record data for specified lengths of time. The sound recorders can separate frequencies–useful to filter out high frequency calls like those of primates, from low frequency calls of frogs, making analysis easier. A spectrogram feature renders the aural in image form, making it easier for the researcher to visually distinguish call characteristics of a species.

Read more about Raorchestes cf. nerostagona, the Malabar torrent frog (Micrixalus fuscus) and the primitive wrinkled frog (Nyctibatrachus vasanthii), and their ingenious wooing techniques.

Here, local volunteer Eskimutthu examines
the monkey proof enclosure for sound recorder.
Photo credit: K. S. Seshadri

One other objective of the project is to expand awareness among local youth by enrolling them in a citizen science initiative to monitor anurans in the agrarian landscape in the foothills of KMTR. Volunteers will train in the use of the sound recording and climate data logging gadgets and the data gathered over the years will be analyzed to predict impacts of climate change on anuran populations.

India is home to 277 anurans of which about 150 occupy the IUCN Red List for threatened species. This matches observations on amphibian populations decline across the world. Many of these anuran species have been recently described to science and are already in danger of extinction. The KMTR pilot study on anurans bagged the Future Conservationist Award from the Conservation Leadership Programme and Save our Species Campaign. Conservation Leadership Programme (CLP) is a US-based consortium which is funded by British Petroleum (BP) Foundation, with Wildlife Conservation Society (WCS), Flora and Fauna International (FFI), Conservation International (CI) and Birdlife International. The team led by Seshadri K.S. includes advisors Dr. T. Ganesh, Dr. R. Ganesan and Dr. Soubadra Devy, colleagues Allwin Jesudasan, Mrugank Prabhu, Mathivanan, and field assistants Chian and John. Seshadri and Allwin will present the findings of their study in the 25th International Congress in Conservation Biology (ICCB) organized by Society for Conservation Biology in New Zealand in December 2011.

Read more
Eavesdropping on the wild: Monitoring frogs and toads in KMTR, Agasthya Vol 5.2
Seshadri encounters more than frogs on his nocturnal expeditions. Read Night Life of Kodayar to know more.