Roads And Railways: Death Traps For Tigers

Expanding transportation network through Chitwan National Park in Nepal could reduce tiger numbers, reveals a study.

Asian Scientist Magazine (Jul. 20, 2022)–Nepal’s Chitwan National Park, a UNESCO World Heritage site tucked at the foot of the Himalayas, is one of the last refuges of the Bengal tiger. According to the third nationwide survey done in 2018, Nepal is well on track with its pledge to double tiger numbers by 2022. But a seminal study by researchers in the United States and Nepal predicts that much of this progress could come undone as the government plans on expanding its transportation network, which will cut through the national park. The study was published in PeerJ.

Dr. Neil Carter, lead author and assistant professor at the University of Michigan, said that the lack of knowledge about the consequences of building roads and railways within tiger ranges spells trouble for these endangered cats. The transportation networks can leave critical habitats forever fragmented while leading to tiger deaths from vehicle collisions and the displacement of the wild prey they rely on.

The researchers developed an advanced simulation model to forecast how roads close to the Chitwan National Park and the proposed railway intersecting the reserve would affect its tiger population in the next 20 years.  The model predicts that vehicle collisions on the existing roads will kill 46 tigers, and if the proposed railway is constructed, that will kill 30 more tigers. That will dwindle Chitwan’s comparatively small population of tigers from 133 to just 51 animals.

Co-author Narendra Pradhan from Nepal’s regional office of the International Union of Conservation of Nature (IUCN) told Mongabay how the death of a few tigers could have a reverberating effect on the overall population. The study focuses on the female tiger population and their dependent cubs to depict population growth. Pradhan said that female tigers do not just birth young ones, but research shows that they also ensure the cubs can fend for themselves and reach adulthood.

The study urged decision-makers to implement smart-green infrastructure planning around tiger ranges. That includes utilising wildlife crossing structures like overpasses and underpasses to allow tigers to roam freely across the landscape and also identifying ‘no go’ zones to steer clear of key tiger source populations such as in the Chitwan National Park. Researchers of this study suggested revisiting the new railway placement and considering measures like reducing track curvature and train speed within tiger habitats and restricting traffic volumes and speeds on the existing roads.

Although the study’s projections were based on tiger movement records dating back to the 1970s, the findings call for more robust estimates from field research to improve conservation efforts.

“There’s still much we need to learn about the effects of roads and railways on tiger behaviours and populations,” authors told PeerJ. “But we think that models like ours as part of a suite of monitoring techniques would enable the development of more comprehensive environmental impact assessments of new transport infrastructure projects early in the planning phase before it is too late.”

Source: University of Michigan; Photo: Shutterstock

The article can be found at: Forecasting effects of transport infrastructure on endangered tigers: a tool for conservation planning. 

Asian Scientist Magazine is an award-winning science and technology magazine that highlights R&D news stories from Asia to a global audience. The magazine is published by Singapore-headquartered Wildtype Media Group.

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