In our backyard Environment

Why the loud yellow Indian Bullfrog is a survivor

The Indian Bullfrog at Delhi’s Sanjay Van

The Indian Bullfrog at Delhi’s Sanjay Van   | Photo Credit: Chandra Bhushan Maurya

As the monsoon arrives, our appetite for pakodas becomes insatiable. So it is for the animals around us, except that they are blessed with a far more diverse menu than ours.

Frenzied mating and a voracious appetite come together to ensure the survival and procreation of the amphibian we’re going to talk about today. At any other time during the year, the Indian Bullfrog (Hoplobatrachus tigerinus) roam alone and have a varied dull olive green-brown appearance, camouflaging well with their immediate surroundings.

When the rain comes down, their breeding season begins, and the males, now yellow, with two blue vocal sacs, set out in search of females, that are generally larger. If you find a big congregation of adults, with the yellow males on top of dull-looking females in and around water bodies around this time, you know what they’re upto.

Classified under the International Union for Conservation of Nature’s (IUCN) Least Concern category, it is one of the most familiar and abundant frogs of South and South-East Asia, and also the largest frog found in the Indian Subcontinent. They can be identified by the pointed snout and long hind limbs, which help them jump.

Being nocturnal and formidable ambush predators, they lie in wait for their unsuspecting prey to come closer before lunging and grabbing them with their mouths. At times they may swim or stealthily hop towards their prey in order to catch them by surprise. The powerful jaws and sharp teeth, efficient tongue-play, and fairly large hands allow them to grab, constrict and push its helpless meal inside the mouth bit by bit.

With a large appetite and complete lack of dietary preference, they are known to feed on almost anything, which includes a wide array of both vertebrates and invertebrates including insects, worms, snakes, rodents, fish. They often engage in cannibalism by feeding on smaller individuals of their own kind and on other frogs. Even their tadpoles have been observed to feed on smaller tadpoles of their own kind as well as on tadpoles of other frogs in the vicinity.

In the way of the Nature, they also are an important prey-base for several other creatures like birds, bigger snakes, and at times desperate carnivore mammals. Rat snakes for instance live in sewers and feed on the frogs that also inhabit the area.

The Indian Bullfrog’s loud croaking call, attracts the opposite sex, but also predators, especially in areas with freshwater bodies like ponds, marshes, and lakes, a habitat that they prefer. Their feet are nearly entirely webbed to help them adjust to the water and the vegetation surrounding it. When threatened, they can jump on the surface of the water, just like on land, despite being large in size.

Until late into my career as a naturalist, I had only heard this frog in videos posted online. Three years ago, around this time, I got an opportunity from WWF-India to work on a publication on the wetlands of Keoladeo National Park (formerly called Bharatpur Bird Sanctuary) in Rajasthan.

On a late evening recce, the silence of the park burst with an echoed repetitive call of a creature. Somehow, the call seemed urgent and not normal, more like a plea! On investigating further, I found an unfortunate bullfrog in the jaws of a big Indian Rat Snake near the reeds of the wetland.

On seeing me, the snake slowly wriggled across the periphery of the wetland and made it into the denser reeds. At first, the call became a little more desperate, slowly fading and disappearing completely thereafter.

At the once quaint DSOI Army club in Dhaula Kuan, where evenings revolved around the adults engaging in drinks and dinner, with the young people playing video games at the club arcade, I would stand around and watch the swimming pool. The faint memory of those frogs made me realise much later, that they were all Indian Bullfrogs.

Bullfrog legs are considered a delicacy and they are illegally hunted and served in several places across the country even though the species is protected under Schedule IV of the Wildlife Protection Act of India, 1971. It is the most hunted frog across the country and the forest department works diligently towards any leads to try and curb its consumption.

Their opportunistic feeding behaviour, prolific breeding (with large egg clutches) and adaptability makes them invasive in nature, where they tend to overpower other native species, a problem frogs native to Andamans are facing at present. The species was also introduced in Madagascar and the situation follows the same course.

Areas like Sanjay Van and Lodhi Garden are presently homing a large number of breeding Indian Bullfrogs.

The writer is the founder of NINOX - Owl About Nature, a nature-awareness initiative. He is the Delhi-NCR reviewer for Ebird, a Cornell University initiative, monitoring rare sightings of birds. He formerly led a programme of WWF India.

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Printable version | Aug 12, 2020 2:05:06 AM | https://www.thehindu.com/sci-tech/energy-and-environment/the-yellow-indian-bullfrog-croaks-in-the-rains/article32171913.ece

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