Playing Hide and Seek with the Saw-Scaled Viper in Goa

Species Published : Dec 21, 2022 Updated : Dec 27, 2022

In the laterite plateaus of the Western Ghats, one of India’s most venomous snakes, the saw-scaled viper, finds a safe habitat

It’s a sun-soaked September morning after a night of torrential rain in Goa’s Bhagwan Mahavir Wildlife Sanctuary. Here, at the foothills of the Western Ghats, the forest abruptly gives way to a vast open clearing. The flat-topped plateau of dark laterite, about 50 metres above sea level, is carpeted in neon-green grass and white and yellow monsoon wildflowers.

Red-brown rocks lie inconspicuously baking in the sun. I’d have stumbled carelessly across them had naturalist Omkar Dharwadkar not cautioned me in advance. Entire microhabitats lie concealed under these weathered stones, whose cracks and crevices shelter several small creatures, including scorpions, frogs, crabs, and a variety of snakes.

None among them are as venomous as the saw-scaled viper (Echis carinatus) — the snake we are hoping to encounter today and the reason one must be careful while walking these rocky plateaus.

Laterite plateaus are characterised by swift transformation. The monsoon brings a lush green carpet and wildflower blooms, plus rain-fed streams that spring to life. These streams can disappear within hours in the absence of rain, given the highly porous nature of laterite soil. Photos: Dhritiman Mukherjee
Cover Photo: During the day, saw-scaled vipers hide under loose rocks, like this specimen spotted in Goa’s Bhagwan Mahavir Wildlife Sanctuary. As the smallest of India’s “Big 4” snakes and with superb camouflage, it’s easy to miss them in the rocky plateaus and forests they inhabit. Photo: Omkar Dharwadkar

We don’t have to look too far. Moments into our walk, Omkar artfully lifts a mid-sized rock holding it by its outermost edges. Underneath lies a striking, rather small reptile coiled up and very still. Bulbous golden eyes with vertical pupils sit at the extremities of a thick triangular head. A slender body is covered in serrated, almond-shaped scales patterned in shades of brown and grey. With colourings and markings that blend with the soil it sits on and the rock it lies under, the saw-scaled viper is superbly camouflaged in this laterite habitat.

After a few moments, it unfurls and then rearranges itself into a semi-circular jalebi, its head positioned right at the centre. Slithering in that tight, U-shaped formation, the viper’s keeled scaled rub against each other, producing a distinct sawing sound. It is this very sound that lends the snake its name. Likely irked by the presence of two nosy humans, the creature has decided to display its most defining behaviour trait: stridulation. This refers to the rubbing of scales against each other to emit a warning sound when it feels threatened.

The tightly coiled U-shaped position is characteristic of the saw-scaled viper. On loose sandy or gravelly surfaces, they can move sideways in a motion called sidewinding. Their most defining trait is the act of stridulation when they feel threatened. Video: Omkar Dharwadkar

Along with the Russell’s viper, spectacled cobra, and common krait, the saw-scaled viper makes up India’s “Big 4” — the list of venomous snakes responsible for the most snakebites in the country. For all its potency, the saw-scaled viper is small and unassuming at first glance. On average, the snake measures under 45 cm. The specimen I’m looking at is under 30 cm in length and appears quite calm initially, belying its aggressive nature and deadly character. As Omkar gingerly moves the snake with a stick to position the rock back atop it, the viper strikes like an uncoiled spring, leaving two visible drops of venom on the stick.

Saw-scaled viper venom is hemotoxic, which means it can prevent blood from clotting and cause tissue damage if its snakebite is not treated in time. In scrubland and rocky terrain like the laterite plateaus of Goa, the snakes hide under rocks during the day, emerging at night to prey on frogs, insects, and rodents. They are especially active after rainy nights and are seen more commonly during the monsoon than in other seasons.

From frogs to rodents and crabs, the saw-scaled viper’s diet is vast and varied. In rocky open habitats like this, burrowing frog species like the Fejervarya cepfi are all but invisible to the untrained eye (right). However, flamboyantly coloured freshwater crabs like this purple tree crab (Ghatiana atropurpurea) also traverse the terrain. Photos: Dhritiman Mukherjee (1), Omkar Dharwadkar (2)

Laterite soil is highly absorbent, and there is little trace of the downpour from a few hours ago. With a preference for dry, open areas like these plateaus in Goa’s Western Ghats, the unobtrusive and perfectly camouflaged saw-scaled viper goes mostly unnoticed unless you know exactly where to look. As the day progresses, under rocks and on the plateau floor, we spot many tiny creatures which serve as food for the serpent: a thumbnail-sized Indian burrowing frog; a scorpion of the Hottentotta genus with a sharply defined sting; bright purple and pink crabs. It’s evident that for the fascinating saw-scaled viper to exist peacefully, it needs more undisturbed pockets like this laterite plateau, where there is adequate food, shelter, and, most importantly, little disturbance from humans.