CHENNAI: A healthy breeding population of 31 elusive Leith’s soft-shell turtle (Nilssonia leithii), a critically endangered species protected under Schedule 1 of Wildlife Protection Act, have been spotted in Cauvery river between Mekedatu and Hogenakkal in the state.
Leith’s soft-shell is large freshwater turtle species endemic to peninsular India. So far, only sporadic sightings of the species were recorded in parts of the Thungabhadra, Ghataprabha, Bhavani, Godavari, Krishna, Chalakkudy, Cauvery, and Moyar rivers.
In Cauvery, they were found during a first-of-its-kind pilot study carried out by a group of researchers to estimate their population in the wild in the state. The study results were presented at the third annual research conference on Thursday at the Advanced Institute for Wildlife Conservation.
The study was well received by the state forest department as there has been a steady decline in the soft-shell turtle sightings in recent years due to poaching, habitat fragmentation, hydropower projects and to some extent illegal river sand mining.
Peter Christopher, who is in the process of publishing a research paper along with other researchers from Wildlife Institute of India, Natural History Museum in London and Indigenous Biodiversity Foundation in Pondicherry, told TNIE, “We recorded all the sightings through visual encounter survey from October 2022 to September 2023. It was a painstaking exercise since sightings are difficult as these turtles are highly elusive.”
The researchers said the presence of turtles was confirmed when they were observed while surfacing for breathing, basking on rocks, and through spoor marks. “Visual encounter surveys were carried out 24 times in the Cauvery river between Tamil Nadu-Karnataka border near Hogenakkal,” Christopher said.
He said a comprehensive study should be carried out to better understand their population, feeding and breeding behaviour and threats.
The turtles have distinctive physical characteristics. When young, they possess distinct ocelli (eyes) on their carapace (upper shell) which tend to fade as they grow. Adults exhibit an olive green or greyish hue on their carapace, while their plastron (chest cover) is white or cream-coloured. Notably, many adults display a captivating head pattern with black stripes near the lips and interlaced red blotches. Their diet includes mosquito larvae, crabs, freshwater molluscs and fish, and they grow up to 700-1000mm in length.