GUWAHATI: Meghalaya’s caves never cease to amaze! Scientists from the North Eastern Regional Centre of the Zoological Survey of India (ZSI) in Shillong, have for the first time, spotted a thriving population of trickle stream dwelling frogs (Ingerana borealis) inside a cave in the Nongjri Elaka of East Khasi Hills.
Bhaskar Saikia and Uttam Saikia, both scientists at ZSI (NERC), discovered the tiny frog species, generally found in moving water bodies, at Krem Lymput, a limestone cave with magnificent calcite formations and spacious chambers.
The cave, although not fully explored, is estimated to spread over a few kilometres with a number of passages.
The present report is based on eight specimens of Ingerana borealis, collected over a 14-year period from Krem Lymput.
“All the individuals of the species were collected or spotted while surveying cavernicole fauna. They were found in shallow or moderately deep puddles on the cave floor resulting from flood water erosion. The frogs when disturbed jumped out of water. After a while, they entered the puddle again, suggesting their familiarity with the location. Interestingly, all these puddles (varying sizes of 30-100 cm diameter) were observed to hold only a single individual of this frog,” the report by the scientists said.
During their visit to the cave in March 2019, the cave had a few small pools with waist deep water and water-filled tunnels suggesting extensive flooding during the rainy season. During visits in January 2006 and 2020, the cave was relatively dry with some water puddles and muddy stretches with no flowing water.
“Occurrence of frogs near the cave entrance is not uncommon, especially of frogs belonging to genera Minervarya and Amolops. However, finding this frog deep inside a cave, which so far is known to be associated with forest streams, is interesting,” the report stated.
The present specimens were found about 200 to 1000 metres deep inside the cave, which was a significant distance for a tiny frog.
“Besides, the forest around the cave entrance is replaced by betel nut plantations and there is no stream flowing close by from where it could have entered the cave. The possibility is that the frogs might have entered the cave from nearby areas when it was more suitable (before the primary forest was converted into betel nut plantations) and have been living there for generations,” the report said.
“The continual record of this frog species since 2006 suggests a viable population has been thriving inside the cave and this signifies the cave adaptability of Ingerana borealis which has till now been known to occur along hill streams,” it said.
Interestingly, the specimens collected looked well fed, indicating their adjustment to the resource-scarce cave environment.
The scientists said that similar faunal surveys were carried out at Siju Cave in Garo Hills, where two other species of frogs deep inside the cave were found.
“Although substantial work has been done on the documentation of many faunal groups from a few caves of Meghalaya, little to nothing is known about the cave adaptability of frogs from the region. In this regard, this finding and the subsequent findings from Siju will result in a new scope to understand how frog populations can thrive in a resource scarce environment of caves,” Bhaskar Saikia said.