India's Terai Grasslands Are Vanishing, And Taking Species Found Nowhere Else With Them

The terai is a geographical accident. Where the Himalayan rivers slow down and drop their sediment load onto the plains, they created a belt of waterlogged grasslands, sal forests, and oxbow lakes stretching from Uttarakhand through Bihar and into the lowlands of Nepal. It runs roughly 30 to 50 kilometres wide. For most of human history, it was considered uninhabitable, malarial, flooded seasonally, dense with animals large enough to kill you. That hostility is precisely why it became one of the most biodiverse strips of land in Asia.

The grasses here are not the short-cropped variety most people picture. Elephant grass (Saccharum spontaneum) grows to six metres. Phragmites reeds form walls through which visibility drops to zero. These tall-grass communities, called bhabar-terai in older ecological literature, are distinct from both the Gangetic plains below and the Himalayan foothills above. They are their own world, and they exist nowhere else on earth in this configuration.

The greater one-horned rhinoceros (Rhinoceros unicornis) is the animal most associated with the terai, and the association is correct. Its entire global wild population, roughly 4,000 individuals, lives within this belt, concentrated in Kaziranga National Park in Assam and the Chitwan-Dudhwa corridor. Kaziranga alone holds about 2,600 of them. The rhino is a grazing specialist adapted to tall floodplain grasses; remove the grasslands and you remove the animal, because there is no substitute habitat anywhere.

Less famous but equally restricted: the barasingha, or swamp deer (Rucervus duvaucelii), whose splayed hooves evolved specifically to walk on waterlogged ground. The hard-ground subspecies in Kanha is considered functionally separate; the terai subspecies in Dudhwa National Park in Uttar Pradesh numbers under 2,000 animals. The hispid hare (Caprolagus hispidus) is rarer still, a small, coarse-furred rabbit found only in the tall grasslands of the terai and the Brahmaputra floodplain, with population estimates that have never exceeded a few thousand and may be far lower. The Bengal florican (Houbaropsis bengalensis), a bustard that performs its courtship display by leaping above the grass canopy, has a global population under 1,000 birds. India holds most of them.

The gharial (Gavialis gangeticus), the long-snouted fish-eating crocodilian, is not exclusive to the terai but depends on the clean, fast-moving rivers that flow through it, the Ghaghra, the Gandak, the Rapti. Fewer than 1,000 mature gharial remain in the wild. The terai's rivers are their last serious stronghold.

The malaria eradication campaigns of the 1950s and 1960s, while saving millions of human lives, removed the one barrier that had kept agricultural pressure off the terai for centuries. Within two decades, vast stretches were converted to farmland. A 2020 study published in Biological Conservation estimated that the terai arc landscape, the zone spanning from Uttarakhand to Bihar, had lost over 90 percent of its original natural habitat by the early 21st century. What remains is fragmented into protected patches separated by agricultural land, roads, and settlements.

Fire suppression has compounded the problem in ways that are less visible. Tall-grass communities require periodic burning to prevent succession into scrub and forest. Without fire, the open grassland that rhino, barasingha, and florican require closes over within a decade. Several protected areas in the terai have seen grassland coverage shrink from within their own boundaries because fire management has been inconsistent or politically difficult to implement near human settlements.

The third pressure is linear infrastructure. National Highway 74 cuts through the Terai Arc. Railway lines bisect movement corridors. The animals that depend on connected patches of grassland, tigers moving between Pilibhit and Dudhwa, elephants crossing from Nepal's Bardia into Katerniaghat, are stopped by roads that didn't exist a generation ago.

The rhino recovery is the one story the terai has to offer as an unambiguous success. In 1905, the greater one-horned rhino was estimated at fewer than 200 animals. Strict protection at Kaziranga, combined with anti-poaching enforcement and community involvement in buffer zones, brought the number back to over 4,000. Project Tiger, launched in 1973, stabilised tiger populations across several terai reserves including Corbett, Dudhwa, and Pilibhit, the last of which now has one of the highest tiger densities in India relative to its area.

But the rhino and tiger recoveries mask a more complicated picture. The species that recovered are large, charismatic, and politically useful for conservation funding. The hispid hare has no equivalent campaign. The Bengal florican has no equivalent census infrastructure. The grassland itself, the thing all of these animals depend on, has no dedicated national protection programme in the way forests do. India's Forest Rights Act and its Protected Area network were built around tree cover. Grasslands are legally categorised as wasteland in several states, which makes them easier to acquire for agriculture or development than forest land.

The terai's rivers face their own unresolved crisis. Barrages on the Gandak and Ghaghra have altered flow regimes that gharial depend on for nesting beaches. Sand mining on the Chambal and Rapti removes the gravel bars where gharial lay eggs. The Gharial Conservation Alliance has documented nest success rates collapsing in years of high sand extraction.

What the terai has demonstrated, across seven decades of conservation effort, is that protection works when it is applied to a specific, named animal with political visibility. The grassland as a whole, the six-metre grass, the waterlogged soil, the fire cycle, the river dynamic, has never had that political visibility. And the animals that depend on it most narrowly are the ones with the least time left.