Purple Frog: A Brief Interlude from a Secret Life Underground

It’s the month of June 2023, and I am in the Western Ghats, sitting in a room overlooking the mountains. It is hot and humid, unlike any other June I’ve spent here. The monsoon has arrived, but there’s not enough rain. This year climatologists recorded the area’s weakest monsoon in June in 47 years. The monsoon is changing, and the last couple of years have experienced several extreme events as a consequence. My mind goes back to the super frog, and I am here to research and determine how the erratic and low monsoon will affect its existence. One of the first groups of animals affected by the slightest change in weather patterns are amphibians, especially specialist species like the purple frog (Nasikabatrachus sahyadrensis), which are heavily dependent on the monsoon for their survival. (Specialist species require certain basic weather parameters in their habitats for them to breed successfully.) I’ve spent the last 12 years chasing the first showers and following the odd-looking but very enigmatic purple frog. This year, we’ve already spent 63 days in the field, but since it hasn’t rained enough for all the frogs to breed, our work seems far from over.

Living fossils

The scientific community found out about the existence of the purple frog only in 2003 when it was formally described by scientists Dr SD Biju and Dr Franky Bossuyt from the hill ranges of Idukki in Kerala. But once the species was discovered, its intriguing and secret burrowing life underground and bizarre body morphology put it in the limelight. It was even dubbed as the living fossil among amphibians.

Scientists may have discovered the purple frog rather late, but the frog has long been a part of the lives of the indigenous hill tribes of Tamil Nadu and Kerala. The fact that the indigenous communites knew so much about these frogs and had so many clues about their behavior was only discovered by us scientists much later into our research. In fact, the local tribes have different names for both sexes (padhal for males and padhayal for females), and the frogs also feature in their songs. So, while scientists struggled to understand their biology, these indigenous communities knew so much about their microhabitat, diet, ecology and even their secret lives underground. Finally, it was only in 2012, after years of research, that scientists began to understand their breeding behaviour.

Purple frogs have a long evolutionary history and strong connections with the Sooglossidae family of frogs in Seychelles. This frog’s evolutionary history could support the hypothesis of Gondwanaland — a supercontinent or great southern landmass that consisted of what today is Africa, South America, India, Madagascar, Australia and New Zealand. About 180 million years ago, the Gondwana landscape started dispersing, causing great tension in the Earth’s crust, and eventually, the countries and continents as we know them today were formed. How else could a queer-looking frog from India have close cousins on an island off the coast of Africa? 

Unique breeding behaviour

Purple frogs live underground throughout the year. The females surface above ground just for a day once a year and only for a couple of hours, to mate and lay their eggs. Immediately after the first monsoon showers, the male frogs start calling while they are still underground. It’s almost like the first rains are their alarm clock! There have also been instances of some individuals wandering alone above ground, looking lost during the first rains. But they wait patiently until there is enough water in the seasonal streams. When they feel there is enough water, they use the opportunity to become the first ones to breed (as opposed to other frogs and fishes). This way, they also ensure there is less competition and predation in their breeding habitat. Once the stream conditions are perfect, the mating begins. The females, almost three times the size of the males, emerge from their underground homes to their breeding sites, with the males sitting piggyback on them. The journey is not easy as there are predators, including owls and checkered keelbacks, waiting to devour them. Sometimes common Indian toad males may try to mount the purple frog, who struggles to get rid of them. The most dangerous thing for them, however, is the road networks bisecting their habitats. In many places, these roads are death traps for these frogs. Besides this, other pressures like linear intrusions, dams, uncontrolled tourism, littering etc., seriously threaten the breeding strategies they have evolved and adapted over a long time.

I first saw a purple frog in 2006 — a rescued individual trying to find its way out of an aquarium tank in a forest department facility. I wouldn’t have imagined that years later I would spend decades of my life working towards the conservation of the species. I started researching these frogs initially with the Zoological Society of London’s EDGE of Existence programme. That is when we realised how much attention this species needed and how without proper conservation attention, a species with such an amazing evolutionary history could easily be gone before we knew it.

Rebranding the purple frog

The first step in the conservation of any species is to build awareness and get the species as much visibility as possible. Yes, it is indeed a popular frog. It doesn’t need an introduction among the scientific and naturalist communities. But hardly anyone out of these circles had even heard about the frog. The question of how we conserve a species if it is not well-known pushed us to kickstart an awareness campaign alongside our research. Often big, charismatic species are loved, but how could we draw attention to a bizarre-looking frog with so many stories?

And suddenly, we had a brainwave! We decided to use their one-day surfacing behaviour and compare them to the legendary mythological character King Mahabali, who was banished to the underworld and allowed to visit his people once a day every year. We started calling it the Mahabali frog and highlighted its behaviour of emerging for just one day, which people could relate to. We then pitched the idea of having a state amphibian and proposed that the Mahabali frog be considered. This campaign gained much attention — maybe because of how unique the frog looked, people found it amusing, and the media took it up.

The awareness campaigns did have an impact. While it may still not have mainstream recognition, many people know about the frog. In 2020, the frog was also moved from the “Endangered” category to the “Near Threatened” category on the IUCN Red List based on distribution surveys, indicating a higher population than previously thought. The species has also been put on Schedule 1 in the 2022 amendment of the Wildlife Protection Act, which accords it the highest level of protection. Despite the protection status, changing climate and the fact that a majority of its breeding habitat falls outside protected areas, the conservation of this species will still require a lot of attention.

Despite all the positive news, several breeding adults are killed on roads as they are on their way to lay eggs each monsoon. This, coupled with climate change and the erratic monsoon, will seriously threaten their survival.