- Camera traps have captured tigers roaming at an elevation of 3,165 meters (10,384 feet) in eastern Nepal’s lower Himalayas — the highest they’ve ever been recorded in the country.
- Experts suggest a range of factors for this, including a growing tiger population that’s crowding some of the big cats out of the lowland plains and further uphill.
- Another set of camera trap images were captured in Dadeldhura district in western Nepal, which a previous study identified as a climate refugium, where temperatures remain relatively stable, allowing species to persist during regional and global climate changes.
- Other large mammals have also been recorded on camera trap here, including many that, like tigers, were previously thought to be confined to lower-elevation habitats.
KATHMANDU — During his regular patrol in the forests of Dadeldhura district in Nepal’s westernmost tip in 2020, forester Bishnu Prasad Acharya heard something strange from a temple priest. “He told me that he sees a Bengal tiger roam the dense forests in the hills now and then,” Acharya recalls.
“But I didn’t believe him,” he adds. Nepal’s tigers (Panthera tigris tigris) are found in the country’s southern flood plains, ranging up to the foothills of the Chure range. The temple in Dadeldhura is located in the Mahabharat range, or the lower Himalayas, further north and even higher in elevation than the Chure range. If the priest really had seen a tiger, then, it was two mountain ranges and more than 2,000 meters (6,600 feet) in elevation removed from its known habitat.
When the priest insisted it was a tiger, Adhikari approached WWF’s Terai Arc Landscape (TAL) program to request they set up camera traps in the area. The TAL program, which was already considering studying the impacts of climate change in the area, agreed, setting up 62 camera traps between March and April 2020.
To the researchers’ surprise, a tiger was caught by a camera placed at an elevation of 2,511 m (8,238 ft). This was a record for Nepal, which was later shattered by another camera trap image of a tiger at 3,165 m (10,384 ft) in eastern Nepal. The highest a tiger has ever been recorded is in another Himalayan country, the tiny kingdom of Bhutan, at a nose-bleeding 4,400 m (more than 14,400 ft). “Although it wasn’t visible in the images, it was snowing in the area when the photo of the tiger was captured,” Acharya says.
The news spread not only in Nepal, but also made headlines around the world, spawning the theory that climate change may have forced the tiger, previously believed to be restricted to Nepal’s floodplains, to move uphill in search of a cooler climate. A previous study had also identified this region of the eastern Himalayas as a “climate refugium” — a small zone that maintains relatively stable local temperatures, allowing species to persist during regional and global climate changes.
A recent study documenting the results from the camera traps shows that Dadelhura’s forests aren’t just important for tigers, but are also a valuable habitat for a wide range of other mammals, some of which had until now only been recorded at lower altitudes.
After analyzing the camera trap results, researchers described the region as “biologically diverse and ecologically significant,” home to a host of threatened and even endangered species.
The network of camera traps photographed 23 species, from the near threatened (the Himalayan goral, Naemorhedus goral, and the striped hyena, Hyaena hyaena), to the vulnerable (sambar deer, Rusa unicolor), and the endangered (Indian pangolin, Manis crassicaudata). Researchers posit that seven more species of mammals could be living in the area, such as the vulnerable Himalayan serow (Capricornis thar) and clouded leopard (Neofelis nebulosa), and endangered dhole (Cuon alpinus) and red panda (Ailurus fulgens).
“The photo of the striped hyaena we captured during the study at an elevation of 2,030 [meters, or 6,660 ft] is the highest-elevation record of the animal in Nepal,” Kanchan Thapa from WWF Nepal and lead author of the study, told Mongabay.
“The number of mammal species we found in Dadeldhura was comparable to the ones we find in neighboring Shuklaphanta National Park in the plains,” he added. “This also highlights how important the forest is in terms of conservation.”
The researchers note that many factors may have played a role in creating a favorable environment for so many mammals to survive in the area, which also provides a contiguous habitat between protected areas in Nepal and India, such as Shuklaphanta National Park and Nandhaur Wildlife Sanctuary.
One of these factors is the region’s forest cover. At 1,143 square kilometers (441 square miles), the forest cover as a proportion of Dadeldhura’s total area is the highest of any of Nepal’s 76 districts. The district’s gradient also gives rise to a rich range of vegetation, from subtropical to subalpine.
Another factor making the region attractive to megafauna like tigers is the recovery of forests as a result of successful community-led forestry programs.
The study also suggests that as the tiger population has increased in the species’ core habitats in the southern plains, these high-altitude forests may serve as a refuge for tigers looking for unclaimed space.
“As we know, tigers are very territorial, and some tigers are pushed to the fringes by more powerful ones,” Thapa said.
The authors suggest the tiger they photographed may have come to Dadeldhura from one of two key protected areas nearby: Shuklaphanta National Park (a distance of 24 kilometers, or 15 miles, in a straight line), or Nandhaur Wildlife Sanctuary in India, some 32 km (20 mi) away.
Acharya, the forester and also a co-author of the study, suggested another possibility. He told Mongabay that in the past, Nepal’s hills and plains maintained good forest connectivity, allowing tigers to move freely to and fro.
“That’s the reason why old people in the hills still remember seeing tigers, which many of us believe to be either leopards or other wild cats,” he said. “If it weren’t for the discovery, we would have taken such claims lightly. But now there’s room to believe that there’s some grain of truth in such statements.”
Conservationist Babu Ram Lamichhane from the National Trust for Nature Conservation (NTNC), a semigovernment body, said tigers are generalist species that thrive in a range of habitats, from the frigid conditions of eastern Russia and Central Asia, to the salty mangroves of Bengal. They may have roamed the hills of the lower Himalayas in the past, he suggested, becoming limited to the plains only more recently as their numbers declined.
But there’s a limit to the number of tigers the hills can support, given that the prey population there “is not sufficient.”
“The deer found in the hills have lower body mass compared to those in the plains, [so the tiger] population may not grow much in the hills compared to the plains,” Lamichhane said.
Now that research has established the value of the area as a climate refugium, it’s time to take action to conserve the area, the authors of the study say. They suggest that community forest leaders include species protection actions in their periodic operation plans to help keep the habitat intact.
Forestry authorities in Sudurpaschim province, where Dadeldhura is located, have proposed that the area be declared a forest conservation area.
“It is for the local people and the government to decide what kind of a conservation model they want to adopt,” said Lamichhane, who wasn’t involved in the study. “However, it can’t be denied that this area should be protected.”
Thapa said the findings “also have implications for areas in India adjoining Dadeldhura.” He added they show that those areas also have high potential for wildlife diversity, and need to be protected.
Thapa, G. J., Wikramanayake, E., Jnawali, S. R., Oglethorpe, J., & Adhikari, R. (2016). Assessing climate change impacts on forest ecosystems for landscape-scale spatial planning in Nepal. Current Science, 110(3), 345. doi:10.18520/cs/v110/i3/345-352
Thapa, K., Subba, S. A., Thapa, G. J., Dewan, K., Acharya, B. P., Bohara, D., . . . Malla, S. (2022). Wildlife in climate refugia: Mammalian diversity, occupancy, and tiger distribution in the western himalayas, Nepal. Ecology and Evolution, 12(12). doi:10.1002/ece3.9600