Stretching across the fertile lowlands at the foothills of the Himalayas, the Terai Arc Landscape (TAL) is a transboundary conservation area that spans India and Nepal, forming one of the most biologically rich regions in South Asia. This mosaic of grasslands, riverine forests, wetlands, and sal-dominated woodlands is not only critical for iconic megafauna like tigers and elephants but also a paradise for Birdlife of the Terai Arc, home to an astounding over 600 species of birds.
The Indian part of the Terai Arc Landscape includes 13 protected areas, such as Corbett, Dudhwa, Rajaji, and Valmiki Tiger Reserves, while the Nepalese side safeguards its biodiversity through 14 protected areas, including Chitwan, Bardia, Shuklaphanta, and Parsa National Parks. Together, these reserves form a contiguous ecological corridor that supports both resident and migratory birds across altitudinal and seasonal gradients.
From critically endangered species like the Bengal Florican and White-rumped Vulture to winter visitors such as the Bar-headed Goose and colorful residents like the Indian Pitta and Great Hornbill, the birdlife of the Terai Arc reflects the region’s incredible ecological diversity. Whether you’re a seasoned ornithologist or a curious traveler, the avifauna of the Terai Arc promises awe-inspiring encounters with some of the subcontinent’s most fascinating bird species.
Why is it Called the Terai Arc Landscape?
The word “Terai” comes from the Hindi word Tarai, meaning “moist land”, which aptly describes this lush, low-lying belt lying south of the Himalayan foothills. The Terai is characterized by its flat alluvial plains, formed by the sediments carried by Himalayan rivers such as the Ganges, Ghaghara, Karnali, and Gandak. The constant interaction between these rivers and the forested land has shaped a rich mosaic of tall grasslands, wetlands, riverine forests, and sal-dominated woodlands, making it one of the most productive and fertile ecosystems in the region.
A Landscape of Extraordinary Diversity
What makes the Terai Arc Landscape exceptionally diverse is its geographic position as an ecotone—a transitional zone between the Himalayan uplands and the Gangetic plains. This unique location supports a wide range of habitats, allowing species from both lowland and montane regions to coexist. Seasonal monsoons, perennial river systems, and varying elevations contribute to high habitat heterogeneity, attracting both resident and migratory species, from aquatic birds to forest raptors, and from herbivores like swamp deer to top predators like tigers. This diversity extends to human communities as well, many of whom have coexisted with the landscape for generations, depending on it for resources while also playing a role in its conservation.
A Lifeline for Tigers
The Terai Arc Landscape is of critical importance to the long-term survival of the Bengal tiger (Panthera tigris tigris) in the Indian subcontinent. It contains some of the most well-connected tiger habitats, allowing movement between protected areas in India and Nepal through forested corridors and riverine belts. Tiger reserves such as Corbett, Pilibhit, Dudhwa, and Valmiki in India, and Chitwan, Bardiya, and Shuklaphanta in Nepal, serve as vital breeding grounds. The connectivity offered by this landscape enhances genetic exchange between tiger populations, reducing the risks of inbreeding and ensuring population resilience.
Moreover, the Terai Arc plays a key role in the global tiger recovery strategy. The governments of both India and Nepal, along with conservation partners, have prioritized this region for tiger corridor protection and landscape-level conservation. This holistic approach not only benefits tigers but also helps conserve countless other species that share their habitat.
Major Avian Attractions of the Terai Arc Landscape
The Terai Arc Landscape is a birdwatcher’s dream come true. With over 600 bird species recorded across its mosaic of grasslands, wetlands, forests, and riverine ecosystems, this transboundary region supports a dazzling array of avifauna, from globally threatened species to colorful residents and long-distance migrants.
Grassland and Wetland Specialists
Among the most iconic avian attractions of the Terai are its grassland specialists, many of which are globally threatened due to habitat loss. Chief among them is the Bengal Florican (Houbaropsis bengalensis), a critically endangered species that performs an extraordinary breeding display during the monsoon season in tall grasslands. The Terai is one of the last strongholds for this elusive bustard, particularly in protected areas like Shuklaphanta National Park and Dudhwa Tiger Reserve.
Wetlands and riverbanks attract large congregations of waterfowl and waders, including the majestic Sarus Crane (Antigone antigone), the tallest flying bird in the world and a symbol of marital fidelity in local folklore. Lakes, oxbow wetlands, and floodplains of the Karnali, Rapti, and Gandak rivers are frequented by Bar-headed Geese, Ruddy Shelducks, Black-necked Storks, Painted Storks, and Asian Openbills. Winter months bring a dramatic influx of migratory birds, including Northern Pintails, Common Teals, Ferruginous Ducks, and Garganeys, making the region a hotspot for waterbird watching.
Forest and Riverine Birds
The sal forests and riverine woodlands of the Terai are home to a wide variety of birds, from small insectivores to powerful raptors. Notable species include the Great Hornbill (Buceros bicornis), known for its massive casque and loud wingbeats, and the Oriental Pied Hornbill, which can often be seen flitting between fruiting trees in lowland forests. Mixed hunting parties in the forest canopy may include Maroon Orioles, Common Woodshrikes, Velvet-fronted Nuthatches, and Asian Paradise Flycatchers.
Birds of prey are also abundant and include Changeable Hawk-Eagles, Crested Serpent Eagles, and Shikras, as well as rarer species like the Pallas’s Fish Eagle and the Greater Spotted Eagle both considered vulnerable on the IUCN Red List.
Endangered and Critically Endangered Species
The Terai Arc Landscape is a refuge for several endangered and critically endangered bird species, whose populations have suffered due to habitat degradation, poisoning, and human disturbance. Key among them are:
- White-rumped Vulture (Gyps bengalensis) – Critically Endangered
Once common across the region, this vulture’s population plummeted due to the veterinary drug diclofenac. Now slowly recovering in some areas, particularly near vulture restaurants and protected roosts. - Slender-billed Vulture (Gyps tenuirostris) – Critically Endangered
Rare and highly range-restricted, this species shares similar threats as its white-rumped cousin and is occasionally spotted in protected stretches of the Terai. - Lesser Adjutant Stork (Leptoptilos javanicus) – Vulnerable
This large, bald-headed stork is often seen solitary or in pairs near marshes and floodplains in areas like Koshi Tappu and Shuklaphanta. - Black-bellied Tern (Sterna acuticauda) – Endangered
A graceful riverine bird, now in decline due to sand mining, egg predation, and water pollution. - Swamp Francolin (Ortygornis gularis) – Vulnerable
This elusive bird prefers dense tall grasslands and is best seen at dawn or dusk in reserves like Dudhwa and Shuklaphanta.
Migratory Highlights
Every winter, the Terai turns into a haven for migrants from Central Asia, Siberia, and the Tibetan plateau. Spectacular flocks of Demoiselle Cranes, Greylag Geese, Black-tailed Godwits, Marsh Harriers, and Pied Avocets adorn the wetlands. Their arrival not only enhances biodiversity but also signals the health of the habitat.
River Corridors as Birdlife Highways at Terai Arc
Major rivers like the Gandak, Ghaghara, Rapti, Karnali, and Koshi not only shape the landscape but act as flyways and foraging grounds for numerous waterbird species. Birding along these rivers, especially during winter, reveals large mixed flocks and rare migratory surprises.
Conclusion: A Living Symphony of Wings and Wetlands
The Terai Arc Landscape, straddling India and Nepal, is more than just a tiger corridor—it’s a vibrant, pulsating world of wings, songs, and seasonal migrations. Its wetlands, oxbow lakes, riverbanks, and grasslands together create one of the most ecologically significant bird habitats in South Asia. From the endangered Bengal Florican hidden in tall grasslands to flocks of Bar-headed Geese soaring above Himalayan rivers, the region hosts an extraordinary range of avian life.
Places like Corbett, Dudhwa, Kishanpur, Valmik, Bardiya and Chitwan are not just birding destinations, they are vital ecosystems that sustain global biodiversity. These habitats serve as breeding grounds, stopovers, and winter refuges for both resident and migratory species. Their conservation is crucial not just for birds, but for the health of the entire landscape.
As human pressures and climate change threaten wetlands across the world, the Terai Arc remains a beacon of hope showcasing how cross-border conservation, community participation, and habitat protection can preserve one of nature’s greatest spectacles. Whether you’re a seasoned ornithologist or a traveler seeking serenity, the birds of the Terai will always welcome you with a flutter, a call, and the timeless rhythm of the wild.
