The snakes were not supposed to be there. Yet, there they were. When biologist Dikansh Parmar’s friend called to tell him about finding a king cobra among the cement piles near the platform of a railway station in Goa, he was “amazed and excited”.

Then it intrigued him: “How come the snake is here? How did it reach here? The area is not a king cobra territory.” The incident prompted Parmar to check for records of king cobra sightings in territories unsuitable to them. This was not a one-off incident. People have been documenting snakes on trains on their cell phones for quite some time.

Parmar, now based at the University of Bonn, and at the Institute for the Analysis of Biodiversity Change, along with an international team of researchers, uncoil the story behind the appearance of the snakes in a recent study published in Biotropca.

The world’s longest venomous snake, the king cobra (Ophiophagus kaalinga), may be hitching a ride on trains, offloading itself in territories both ecologically compatible and incompatible, triggering serious conservation and public safety worries.

The researchers mapped 47 verified king cobra locations in Goa. Using 22 years of snake rescue data from the Animal Rescue Squad Goa (ARSG) and advanced species distribution modelling, they found five outliers. These five had one common element: all were found near active railway lines and stations, an environment alien to a forest-dwelling apex predator.

“Finding a king cobra at the Chandor railway station in Goa was surprising for everybody in the rescue squad,” says Parmar, who has been associated with the ARSG for the past five years, supporting the organisation as a herpetologist. “It was not supposed to be there.”

Based on snake-rescue records, interviews with locals and sightings, the first-of-its-kind study shows railways as surprising dispersal routes, highlighting an under-appreciated consequence of human linear infrastructure.

“This means that the movement of species may not just be about ecological suitability anymore,” says Hinrich Kaiser, professor and co-author of the study. “It is now also about connectivity to human transport networks.”

The authors theorise that snakes are likely hopping on trains when they stop for a long period in prime cobra habitat in the Western Ghats before proceeding to Goa’s lowlands. It could also be that their hideouts are flooded in rains and they are seeking dry places. They could also be searching for food, which is plenty because freight trains are loaded with grains that attract rodents.

“One of the greatest strengths of this study is its use of records collected over a wide range of time, highlighting the importance of data curation that can be used in downstream research,” says Justin M. Bernstein, AMNH Postdoctoral Fellow, Division of Vertebrate Zoology, American Museum of Natural History.

For the research, Parmar spent years, imbibing local knowledge of king cobra habitats, spread across wet and slippery slopes of the Western Ghats, splintered landscapes and human-made environments, and coupling them with scientific models.

“Every record, every rescue, every kilometre walked mattered,” he says. “Only by pushing physical and mental limits could we begin to understand these snakes and their hidden journeys.”

The dispersal of king cobra through railways falls at the intersection of conservation and public safety. India has 69,181 km route length with 1,35,207 km total track length. King cobras, already endangered, hypothesised to be riding on trains and ending up in unsuitable places, could starve or die. Parmar says king cobra is a forested animal. The hustle and bustle of railways is not its thing.

On the other hand, human safety is an important consideration. To date, no snakebite incidents have been recorded on trains, and maintaining this record is possible through preventive measures and awareness. Encounters with wildlife in unexpected settings can lead to unpredictable reactions from people, which can increase the risk of accidents. Considering that India records an estimated 58,000 snakebite-related deaths annually, all occurring outside train environments, being vigilant can help ensure that such incidents continue to remain absent in railway contexts.

“It is critical for us to understand how infrastructure from humans can also influence where species are found, which ultimately aid in conservation efforts and identifying the factors that might drive species distribution patterns,” says Bernstein.

The study highlights the importance of collaboration between scientists and wildlife rescue organisations. The raw records from rescuers were  verified, examined, georeferenced, and analysed by the scientists, transforming into robust and meaningful scientific research.

“It shows that investing in and trusting local expertise is not just a nice thing to do for the snakes and for the local residents,” says Kaiser, “but it can be a key component of making real scientific discoveries that can help us become more aware and perhaps coexist better with the wildlife around us.”

In order to minimise  snakes-and-human encounters on trains, Parmar suggests railway authorities collaborate with NGOs, similar to how scientists work with rescue organisations. Railway stations could maintain state or district level rescue contact records, provide basic snake identification and rescue training through the forest department or registered NGOs, and keep a snake-handling tong available for emergency situations.

In addition, citizen science initiatives could be introduced to involve the public in wildlife-friendly practices. Passengers can be encouraged to avoid throwing leftover food out of trains or leaving it inside coaches.  

The researchers also call for further behaviour and genetic analyses to test the railway-dispersal hypothesis. Accurate species identification is crucial, particularly for species with restricted or endemic ranges. For example, Ophiophagus kaalinga or the king cobra is endemic to the Western Ghats. If an individual of this species is found in a different area, such as the Northeast, there is a risk of misidentification or accidental release into an unsuitable habitat. In such cases, genetic analysis can be employed to confirm the species’ identity. Once confirmed, the individual can be relocated back to its natural range in the Western Ghats. Such practices help prevent species distribution pollution, and avoid unintended ecological impact.

“It is important to think about these outcomes when the construction of new infrastructure is taking place,” says Bernstein.