When the State government announced the institution of the Tamil Nadu Endangered Species Conservation Fund (TNESCF) in its 2024 Budget, a rare frog having a bloated body, pointed snout and stout limbs grabbed space in the posters of the special fund.
The Purple Frog, two species of which are found in unique habitats in Tamil Nadu, are among the many lesser known and endangered species to be covered under the fund.
Believed to have co-existed with dinosaurs, the Purple Frog is often dubbed as a ‘living fossil’, as it has similarities to the Sooglossidae family of frogs in Seychelles, supporting the Gondwana landmass hypothesis.
Belonging to the Nasikabatrachidae family, the soil-dwelling frog is endemic to select habitats in the Western Ghats in Kerala and Tamil Nadu. For years, the amphibian has been drawing the attention of researchers, who are striving to solve the mysteries of its unique year-long subterranean life.
Two types in Tamil Nadu
Tamil Nadu is home to two types of Purple Frog: Nasikabatrachus sahyadrensis and Nasikabatrachus bhupathi. While the first was described by S.D. Biju and Franky Bossyut in Idukki district of Kerala in 2003, scientists of the Centre for Cellular and Molecular Biology, Hyderabad, discovered N. bhupathi, in the eastern slopes of the Western Ghats near the Srivilliputhur Grizzled Giant Squirrel Wildlife Sanctuary in Tamil Nadu in 2017 and named it after Indian herpetologist S. Bhupathy.
The Anamalai hills near Coimbatore is one of the prime habitats of the Purple Frog in Tamil Nadu, while they occur in higher numbers in the Western Ghat mountains in Kerala.
Herpetologist Sandeep Das, who has been documenting and studying the Purple Frog for over a decade, feels the fund will boost efforts to understand the species better and design conservation strategies.
According to him, the Purple Frogs emerge from moist soil after the first monsoon rain hits the ground of their habitats. The male frogs give out mating calls from the burrows itself and they slowly emerge looking for females. After the amplexus (mating among frogs), the females that are almost thrice the size of the males piggyback their pairs to the egg-laying sites, which are inundated crevices along fast-flowing streams. Though they spend hardly a day outside, they have a risky journey to the egg-laying sites as they are easy prey for predators like owls and the water snake.
The females lay 3,000 to 4,000 eggs, which the males fertilise, before returning to the underground. “The eggs develop into tadpoles in seven to eight days and the tadpoles become froglets in 100 to 130 days,” says Mr. Das.
Peculiar mouth
The tadpoles have a peculiar sucker-like mouth which helps them stick onto the rocks in the fast-flowing streams. However, not much is known about their subterranean life after they become adults. “They are not believed to remain in hibernation underground as gut content analysis of individuals that died during excavations had parts of earthworm, ants, termites, and soil mites. The life span of the frog is also being studied,” Mr. Das says.
Major threats
Habitat loss, road networks through their habitats, and climate change are some of the major threats to their survival. Climate change is directly affecting them as their mating process itself is triggered by rain. “If there is no rain after they lay eggs, the egg-laying sites will become dry, leading to destruction of eggs. Heavy rain that causes landslips can also damage their habitats,” he says.
According to J. Peter Prem Chakravarthy, biologist of the Anamalai Tiger Reserve, the use of pesticides in plantation areas like Valparai could also have a direct impact on the Purple Frog.
According to initial assessments, the Purple Frog ranked four on the ‘EDGE (Evolutionarily Distinct and Globally Endangered) of Existence’ priority amphibians list collated by the Zoological Society of London. Though the amphibian was in the ‘Endangered’ category on the Red List of the International Union for Conservation of Nature (IUCN) in 2004 based on early assessments, it was moved to the ‘Near Threatened’ category in 2020, after surveys over the years indicated a much higher population.
The Purple Frog was also brought under Schedule I of the Wildlife Protection (Amendment) Act, 2022.
Focus on lesser-known species
“The focus of wildlife conservation has always been on dominant species. There are several conservation programmes for elephants, tigers, and others. But lesser-known species had not received the attention they deserved. As a result, many lesser-known species are either endangered or threatened or some are even on the verge of extinction. This is true not only of wild animals but also of several plants,” says Supriya Sahu, Additional Chief Secretary, Environment, Climate Change and Forests, Tamil Nadu, explaining the reason for the government to establish the fund.
According to Ms. Sahu, the government will take steps for the conservation of lesser-known species, including the Purple Frog. “The Biodiversity Board of Tamil Nadu has prepared a reference list of endangered species, and we hope to take them up for conservation [under the fund],” she adds.
Apart from the Purple Frog, the fund, with a corpus of ₹50 crore, will cover rare, endangered, threatened, and lesser-known species like pangolin, otter, Nilgiri marten, slender loris, lion-tailed macaque, and dugong.
