Shieldtails: Hidden Beauties of the Underground

Around the year 2008, I was designing a guesthouse in Coorg in a rich wildlife habitat. One day, on a rough jeep path, I came across an unusual snake lying dead, though it had no visible injuries. It was less than a foot long with a leathery yellow and black pattern and a unique tail end. I clicked a few photos and placed the beautiful specimen amid the roadside vegetation. Later, I was able to identify it as a shieldtail. This was my first, rather sad encounter with this beautiful group of snakes.

In September 2021, my friends Vivek Kale, Sadaf, and Rani of the Sahyadri Conservation and Research Organisation (SCRO) and I spent some time walking the Kumbharli Ghat in Maharashtra. Sadaf had a special way with snakes, and Rani with plants. Soon enough, Sadaf pointed out a shieldtail chasing a large earthworm on the edge of the road, rapidly moving towards the oncoming traffic. The lure of the tasty earthworm seemed to have helped the shieldtail overcome its otherwise shy nature (while no research on their exact hunting methods exists, it is believed that shieldtails use chemoreception [respond to chemical stimuli in their environment] to hunt earthworms). We ring-fenced to protect it from traffic. Sadaf was worried the shieldtail would get crushed under a vehicle. “It happens a lot in the monsoons”, he told us. There were days when he would count up to 10 dead shieldtails on this short stretch of road. Within moments, the shieldtail bit the earthworm into two. It seemed to have suddenly noticed the attention and rushed back into the vegetation. “It will surely come back,” Sadaf said as he picked the earthworm parts up and left them slightly off the road to try to ensure the Bombay shieldtail (Uroleltis macrolepis) didn’t risk coming back onto the road with oncoming traffic. 

Species and conservation status

Shieldtails are small harmless snakes that are largely nocturnal. They are a large, unique family (Uropeltidae) of ancient, nonvenomous snakes believed to have started their evolutionary journey around 56-60 million years ago. They are mainly restricted to the wet montane forests of peninsular India (Western Ghats mainly) and Sri Lanka, though a few species occur in other areas like the Eastern Ghats and hills of Central India, where they are the only endemic snakes. Shieldtails comprise 65 species. As per the latest status of the 47 found in India, 6 are “Critically Endangered”, 12 are “Endangered”, 4 are “Vulnerable”, 2 are “Near Threatened”, 12 are of “Least Concern” and the rest are classified as “data deficient” according to IUCN. Most of the 18 species found in Sri Lanka are “Threatened”, though according to evolutionary ecologist and herpetologist Dr Vivek Cyriac, assessments for many species have been done with little available information and may not be accurate.

Life of a shieldtail

These snakes are not well known in terms of their diversity, biology, and natural history. Shieldtails are fairly small snakes, the shortest barely 15–20 cm and the longest 76 cm. They are adapted to a burrowing way of life. Their skull is strong and inflexible, their eyes small, and body cylindrical and covered with smooth scales.

They are called shieldtails because they have a distinctive tail, that is extremely short, thick, and not always tapering compared to other snakes that have much longer tails, and most species have a subcircular keratinous (same substance that forms hair) shield at the tail tip. Some species have pointed tips and others have microscopic points.

Though they seem to prefer the humus-rich topsoil, they are capable of tunnelling deep through relatively hard soil. Their body scales help reduce friction while burrowing and their short, blunt, shield-like tails with their keeled scales act like stoppers and collect the soil behind them as they burrow, ensuring that the excavated soil and organic matter don’t fall back into the tunnel.

When approached by a predator, they do not bite, they coil their body into a ball, hiding their head by tucking it between their coils and displaying their tail (that looks like the head) to confuse predators into attacking the tail. Many have a dull-coloured back but very bright yellow or red underbellies. When threatened, they may turn upside down and twitch to display their contrasting colouration and startle predators. While it has been observed that when being attacked they defecate and the ones with pointed tail tips poke, whether this behaviour has any survival advantage still needs to be assessed. All species eat earthworms. They mate during the rainy season, and females retain eggs that hatch within the mother’s body, effectively giving birth to live babies.

Great diversity

Shieldtails are of great interest to scientists studying the evolution of animals. The diversity patterns of shieldtails in the Western Ghats is unlike any other Indian snake assemblage. According to some researchers, it mirrors the extremely high diversity and endemism of frogs and toads in the Western Ghats. Isolated massifs that were never reported to harbour shieldtails were found to harbour new undescribed shieldtail species, some of the Eastern Ghats species like Rhinophis goweri and Uropeltis rajendrani from the Kolli hills and U. jerdoni from Deverayanadurga and Nandi hills in Tumkur and Bangalore respectively best illustrate this. It’s likely that a high amount of diversity remains to be described, but continued habitat destruction and degradation throughout their range means that we may never know the true extent of shieldtail diversity. A citizen science initiative called the “Shieldtail Mapping Project” is gathering vital information with the help of citizens and is studying and popularising these fascinating snakes. Dr Vivek Cyriac, one of the project coordinators, told me that they have compiled about 360 observations covering 40 species of these snakes from across India. They are also on Instagram (@shieldtails). 

Parallel to Darwin’s finches

Additionally, because of their peculiar geographic distribution, with many hill ranges in South India and Sri Lanka having endemic shieldtail species, some scientists consider them analogous to Darwin’s finches. Darwin’s finches are small land birds named after Charles Darwin, 13 of which are endemic to the Galapagos Islands. It is thought that once their ancestor, the grassquits, arrived in the Galapagos, they diversified and adapted to the different environments found on the Islands, eventually becoming different species. They famously evolved to have different beaks suited to different food types, such as large seeds and insects, allowing them to occupy different niches. In a broader sense, some researchers feel shieldtail evolution could be to the Western Ghats what Darwin’s finches were to the Galapagos.

Local endemics

As the monsoons opened up in October, some friends and I travelled to Yelavali village in Bhimashankar Wildlife Sanctuary. A slight commotion caught my attention. A group of children aged 5-6 years were having an animated discussion with a young man just outside his humble home. With a beautiful shieldtail in front, he was telling the children that this snake was harmless, while the children looked on with a mix of curiosity and fear. I squatted down and looked at the snake, but it was clear that all it wanted to do was get away. “They come out quite often in the rains; they are quite common here and completely harmless,” the young man told me. We took a few quick photos to help with identification and released them. Back home, I checked for references. Fairly quickly, I was able to locate a 2008 paper by David Gower, Ashok Captain, and Sanjay Thakur that described the sheildtail I had handled as the “bicatenate shieldtail” found only in two localities, Bhimashankar and Fangul Gawhan. Sanjay is a good friend, and I called him. He told me, “You just wait, very soon you will read that based on DNA analysis, even the bicatenate shieldtail will be split into multiple species,” which would mean that in the 56-million-year evolutionary history of this unique family of snakes, the shieldtail I had handled was perhaps found only in Bhimashankar and nowhere else in the world!

With inputs from the Shieldtail Mapping Project team.