A Gliding Frog In The Cardamom Hills

Image: Saurabh Sawant/ Creative Commons
The quest to save this little gliding frog could teach us more about ecological restoration.

“Have you seen this frog?”. Translated into Tamil and Malayalam, this question along with a colour photograph was shown to the indigenous and non-indigenous communities of the Mankulam forest in Idduki, Kerala.

If you did, and you were a biologist in haste – you might be forgiven for saying yes, and identifying it as a Rhacophorus malabaricus – ie, the Malabar gliding frog. Except that answer is wrong – that is the fake frog. Another species, called Rhacophorus pseudomalabaricus, was what the researchers from the Conservation Research Group, Florida International University and Zoological Society of London were looking for.

The two are morphologically similar but exist on opposing spectrums of the International Union for the Conservation of Nature’s red list. The Malabar gliding frog is marked as Least Concern – the same as humans – where the false Malabar gliding frog (also known as the Anamalai Gliding Frog) is Critically Endangered. The two frogs don’t share habitats but they’re not very far from one another.

The difference is that while the Malabar gliding frog has a distribution across the Western Ghats, the Anamalai frog is restricted to the Indira Gandhi National Park (now called the Anamalai Tiger Reserve) and its surroundings. Or at least, it was until the researchers used oral testimonies to find their frog in Kerala’s Cardamom Hills.

The locals were aware of the false frog. They said that it flies from one plant to another and that it vocalizes all night throughout the monsoon. The women seemed to have a lower opinion of it, stating that it wasn’t good for a pregnant woman to touch one. Others mentioned that it ate cardamom – many of the tribals now work in cardamom plantations.

The evidence was good enough to rethink the frog’s range. Idduki is nearly 200 kilometres from the Anamalai park. So the researchers set to work exploring the forest, listening for calls – the age-old method of documenting a species existence.

But of all animal and bird noises, frog noise is most difficult to reproduce in words. The Greek poet Aristophanes got close describing it in his play, The Frogs. Berek-ek-ek, koax, koax, berek-ek-ek, koax – he wrote. The scientists weren’t as lucky as the poet. They had to decode and identify the exact croak from various forms of Frog croaks. Fortunately, they had help from artificial intelligence.

Raven Pro 1.4, an interactive sound analysis software, developed by Cornell University, helped them introduce some automation into the process. The software allowed them to analyse multiple audio samples – for many frogs croak in the forests – and isolate the ones they were looking for.

It paid off – they found a foam nest – with pseudomalabaris tadpoles of varying sizes. The final outcome of the study was that the false gliding frog was not as geographically limited as once thought. Indeed, they recommend changing its IUCN rating from Critically Endangered to Endangered.

Frog conservation isn’t often discussed, but it’s an important part of ecosystem management. Frogs are good indicators of a region’s ecological health – frog skins are highly permeable, allowing scientists to study how much bacteria, chemicals, and toxins they absorb from their surroundings. Frogs eat insects and algae and are eaten by birds, fish, monkeys and snakes – to name a few. They’re an important part of the food chain.

But also, frogs are important to research. In the 1920s, the African clawed frog was a useful ad-hoc pregnancy test; if injected with the urine of a pregnant woman, it would produce eggs within 24 hours. And Epibatidine, a powerful painkiller 200 times stronger than morphine, is made from the same species of poison dart frogs; and is being researched for use as a therapeutic drug.

In Mankulam, the researchers also found something else of note. There is a stream of thought in conservation that ecosystem restoration involves removing non-native species of plant – considered invasive and dangerous to local species. But this team found that the Anamalai Gliding Frog was doing just fine with nonindigenous species, including the invasive ones.

The false gliding frog inhabits higher elevations than the Malabar gliding frog, but mostly on vegetation that overhangs over small ponds. Like its ‘real’ cousin, the webs between its hands and feet are bright red – and used to glide from one branch to another.

The Anamalai hills were once in consideration for being a UNESCO world heritage site. The gliding frog itself is the only amphibian from India to be featured on a postage stamp. Any plan to help restore the habitat of the Anamalai gliding frog will need to be part of a larger conservation strategy targeted at the Western Ghats – the hill range in South India that’s older than the Himalayas.

Tadpole hunting in the region has driven other species of frogs into the endangered list. But it is habitat loss that has most threatened the Anamalai gliding frog. Protecting habitats requires an overarching model of conservation that includes the Western Ghats as well.

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