Purple frog or ‘living fossil’ set to be Kerala’s state amphibian-II

Females exit their burrows and home in on a calling male. A male then exits his burrow and crawls onto a female’s back. The female, which is much larger, then carries the male to a breeding site, usually a shaded rocky pool next to a stream fed by rain. She lays her eggs in large clumps, sometimes up to a thousand.

Tadpoles that hatch from the eggs join the inundated stream. They cling to vertical rocks and cliffs covered in a thin film of water using their suckling mouthparts. “They are extremely strange. They attach to rocks very firmly and are difficult to pluck,” says Biju.

The tribals have devised a way to catch these tadpoles by creating an artificial barrier of rocks and vegetation upstream. They block a part of the stream to reduce water flow and render the tadpoles visible. Then, using a broom, they detach the tadpoles from rocks and collect them in baskets downstream.

Though the adult frog itself wasn’t officially described until 2003, Biju’s interviews with tribals suggest that they have known about the tadpoles and harvested them for food since their settlement 30 to 40 years ago.

Biju explains that harvesting wouldn’t have mattered then, when the frogs used to breed in large numbers, but it is now facing other grave dangers. “Most of its habitats are in and around hydroelectric projects and the species’ sex ratio is highly skewed towards males”.

“Usually male frogs are more in number compared to females, while females are extremely rare in case of Nasikabatrachus. During the breeding season, the local community consumes both adults and tadpoles. They specially search for [gravid] females much larger than the males and they carry large amount of eggs,”  Biju says.

A female lays a large number of eggs at a time but survival percentage is very small. “They have other enemies always, predators like insects, snakes and fish. Human beings are now much more dangerous than natural predators. That is the problem.”

Though tadpoles are a monsoon delicacy, adult frogs are eaten for their alleged medicinal properties, like in curing tuberculosis, or for aphrodisiac qualities. “They eagerly wait for the frogs to start calling from under the ground they go and grab them; they are not even allowing the animal to breed,” Biju says.

Unless urgent conservation measures are taken, the frog’s fate is sealed. Biju says that Govt and NGOs have to come together in sensitising tribal people about the importance of amphibian conservation.

Wildlife biologist Jodi Rowley from Australian Museum Research Institute, who was not involved in the study, told The Wire that harvesting frogs for food or traditional medicine is a big issue for conservation of many amphibian species, especially in Asia. “There’s not much actual information on the effect of harvesting on frog populations, though, and even less on harvesting tadpoles, which makes this [study] very important.”

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