What is Terai Arc Landscape (TAL)?
The Terai Arc Landscape (TAL), also known as the TAL, is a trans-boundary landscape situated in India and Nepal near the international border of both countries. The landscape, which spans an area of 49,500 sq. km, is located at the base of the Himalayas. Within this landscape, there are 15 protected areas.
The Indian portion of TAL stretches from the Yamuna River in the west to Valmiki Tiger Reserve in Bihar in the east, covering five states along the Shivaliks and Gangetic plain. On the other hand, the Nepal part is distributed across 14 districts from Rautahat in the east to Kanchanpur in the west and contains six protected areas.
This landscape contains almost all the forests of the Shivalik and Terai regions of India, and over 75% of the remaining forests of the Terai, Churia, and Shivalik foothills in Nepal.
The Features of Terai Arc Landscape
This remarkable transboundary landscape comprises three distinct geographical and physiographical zones.:
- Shivalik (known as Churia in Nepal) constitutes the southernmost and geologically youngest range of the Himalayas. It is characterized by sandstone and conglomerate rock formations that run parallel to the southern boundary of the lesser Himalayan ranges. At times, they are challenging to distinguish from these ranges.
- Bhabar is typified by a low-gradient terrain featuring coarse alluvium, boulders, and a mix of Sal (Shorea robusta) and miscellaneous vegetation communities. These areas are linked with the lesser Himalayan ranges and the lower slopes of the Shivaliks. The Bhabar zone is recognized for its wide, rocky, and porous streambeds (known as raus), which are distinctive traits.
- Terai is defined by fine alluvium and clay-rich swamps that nurture a diverse landscape of tall grasslands, wetlands, and mixed deciduous forests dominated by Sal (Shorea robusta) forest. These habitats thrive along the floodplains of numerous streams and rivers originating in the Himalayas. Among these zones within the TAL, the Terai holds particular significance, listed among the globally important 200 ecoregions for its unique Terai-Duar Savannas and Grasslands. These alluvial floodplain grasslands are renowned as the world’s tallest grasslands, with certain grass species growing taller than seven meters. Explore our popular tiger safari tours in the Terai Belt of India.
The biodiversity value of Terai Arc Landscape
The Terai Arc Landscape (TAL) stands as a biologically diverse eco-region, harboring a rich array of wildlife. It boasts 86 species of mammals, over 600 species of birds, 47 species of herpetofauna, 126 species of fish, and a remarkable count of over 2,100 species of flowering plants.
The expansive tall alluvial floodplain grasslands and subtropical deciduous forests within the TAL sustain one of the world’s highest densities of tigers and host the second-largest population of greater one-horned rhinoceroses. Additionally, the region is a habitat for numerous remarkable wildlife species such as Asiatic elephants, Indian gaurs, sloth bears, dholes, 12 species of wild cervids and bovids, 11 species of canids and felids, along with critically endangered species like the Gangetic dolphin and gharial. This diverse range of plant and animal species significantly contributes to the global biodiversity significance of the Terai Arc Landscape.
Among the rare and endangered avian species within this landscape, two stand out prominently: the Bengal florican and the swamp francolin. Consequently, the conservation of forest tracts within this landscape becomes imperative to protect and preserve these representative endangered fauna.
The Tigers and Tiger Reserve of Terai
The Terai Arc Landscape (TAL) comprises 15 protected areas primarily established to safeguard the tiger population that roams across this expanse. It includes two Level I Tiger Conservation Units (TCUs) — Chitwan-Parsa-Valmiki and Rajaji-Corbett — and two Level II TCUs — Dudwa-Kailali and Shuklaphanta-Kishanpur.
For the sake of management and based on distinct land features, the TAL is divided into two sections. The western part, situated in the Shivalik-Bhabar tracts, is characterized by numerous seasonal streams called “raus” and perennial streams referred to as “sots.” This region accommodates two tiger reserves, namely Rajaji and Corbett Tiger Reserves. Conversely, the eastern portion witnesses the convergence of “raus” and “sots” into the Terai, sustaining water sources throughout the year. Predominantly composed of Terai grasslands thriving on alluvial silts and clay deposits, this area features vast swampy regions attracting migratory waterfowl and providing favorable conditions for species like swamp deer, hog deer, and rhinoceros. The protected areas in this zone—Pilibhit, Dudhwa, and Valmiki Tiger Reserves—are embedded within human-utilized landscapes and sugarcane fields. These protected areas are crucial for transboundary tiger conservation, as they are interconnected with Nepal.
The western section boasts higher forest cover and experiences lower human disturbance, while the eastern part is characterized by intensive agriculture and lower forest cover. Over time, the tiger-occupied area within the landscape has expanded, with new tiger records observed in the Dehradun Forest Division, marking the western limit of tiger distribution in the landscape. Initially, in 2006, tigers were primarily present in and around Tiger Reserves like Rajaji, Corbett, Pilibhit, Dudhwa, and Valmiki. However, by 2014 and 2018, most habitats in the landscape were colonized, indicating a 14% increase in occupancy. Higher colonization was noted in forested areas surrounding Corbett and Dudhwa, as well as non-tiger reserve areas such as Lansdowne, Amangarh, Terai East, Terai West, and Nandhaur Wildlife Sanctuary.
Tiger reserves of Terai Arc Landscape
Rajaji Tiger Reserve
This forest represents the westernmost tiger-occupied area within this landscape. The low tiger population density in the western part of the tiger reserve, attributed to anthropogenic disturbance, prompted the reintroduction of tigers in 2020. This initiative ultimately led to the recolonization of tigers in the forests of Himachal Pradesh and Haryana, which lie further west of the tiger reserve. A tiger previously photographed in Rajaji Tiger Reserve was reported from Simbalbara Wildlife Sanctuary in Himachal Pradesh in 2023. While these reports are encouraging, these forests require improved protection and increased prey populations to facilitate tiger settlement in the area.
Rajaji Tiger Reserve not only stands as the westernmost tiger reserve of TAL but also marks the north-westernmost limit of Asian Elephants in the world. Relocating human settlements from the reserve has contributed to the recovery of the tiger population. According to the latest census, the reserve harbors 54 tigers within its boundaries, and the landscape, in total, supports 78 tigers utilizing the reserve.
Corbett Tiger Reserve
Corbett National Park, renowned as the premier tiger reserve of TAL, not only boasts the distinction of being India’s first national park but also houses the highest number of tigers in the country, as per the latest estimation. The reserve represents the Shivalik and Bhabar tracts of TAL. The Corbett tiger reserve area and its surrounding forests have a rich history of conserving not only tigers but also all other fauna within this landscape. It was from this reserve that the ‘Project Tiger’ was launched in 1973, marking its significance as India’s inaugural national park and a crucial tiger stronghold.
The reserve’s diverse habitats, abundant prey, and perennial water sources make it an ideal habitat for tigers. Apart from tigers, this reserve also stands out as India’s prime location for birdwatching, hosting nearly half of the bird species found in India, including some species with restricted ranges. Moreover, the reserve is exceptionally well connected with other protected areas in the landscape through wildlife corridors.
According to the latest census, approximately 319 tigers utilize this reserve, with a population of 260 tigers within Corbett’s boundaries.
Pilibhit Tiger Reserve
The Pilibhit Tiger Reserve, situated in the Terai region of the landscape, comprises dense Sal forests, tall alluvial grasslands, savannahs, and impenetrable swamps. It serves as a habitat for a diverse array of wildlife, including 35 mammal species and 350 bird species. Among the notable species of great conservation interest within the reserve are the tiger, leopard, sloth bear, swamp deer, Bengal florican, Finn’s weaver, and swamp francolin.
Pilibhit holds significant importance within the Terai Arc Landscape, nestled between the Terai East division in the north, Shukla Phanta National Park in the northeast, and Dudhwa Tiger Reserve buffer division in the southeast.
The Pilibhit forests were officially notified and reserved in 1879, initiating scientific forestry for the first time in 1893. For the subsequent 120 years, the forests were primarily managed for timber production. The habitat of the tiger was neglected until dedicated efforts by some forest officers led to its restoration and the initiation of tiger population monitoring. This restoration effort resulted in the recovery of the tiger population. Subsequently, the area was declared a wildlife sanctuary in February 2014, followed by its designation as a tiger reserve in June 2014. According to the tiger estimation report of 2022, there are 63 tigers within the reserve, with a total of 71 tigers utilizing the reserve’s area.
Dudhwa Tiger Reserve
Dudhwa tiger reserve is a typical and one of the finest examples of terai eco-system in the landscape. This is the only place which holds the viable population of the nominate sub-species of the northern swamp deer. Out of the seven deer species found in India, the reserve has five. This is the only reserve in Northern India having the great Indian one-horned rhinoceros, which was successfully reintroduced here in the year in 1984. Some critically endangered species, such as the Bengal florican and hispid hare find a home here.
Dudhwa tiger reserve, comprising of three protected areas, i.e., Dudhwa National Park, Kishanpur Wildlife Sanctuary and Katerniaghat Wildlife Sanctuary, stands out as the primary protected area complex of the terai.
The Pilibhit, Kishanpur, Dudhwa and Katerniaghat protected areas are more or less contiguous patch of habitat in continuity with the TAL of Uttarakhand and Nepal. It provides an important corridor along the terai between Uttarakhand and the eastern terai forests up to Valmiki Tiger Reserve in Bihar.
Valmiki Tiger Reserve
Valmiki Tiger Reserve stands as the easternmost tiger reserve within TAL, sharing contiguity with Nepal’s Chitwan National Park and linked with Sohagi Barwa Wildlife Sanctuary in Uttar Pradesh. This reserve holds immense significance within the landscape. Valmiki TR’s vegetation has been categorized into seven forest types, with Sal being the dominant tree species.
Over the years, the tiger population in Valmiki Tiger Reserve has notably increased. This rise can be credited to prey restoration efforts within the park and the augmented tiger population in Nepal’s adjoining Chitwan National Park, serving as a source population for tigers in this landscape. The surge in tiger numbers within Valmiki has led to the colonization of Sohagibarwa Wildlife Sanctuary. In a promising development for the eastern boundary of this landscape’s tiger population, tiger cubs and juveniles, photographed within Valmiki Tiger Reserve, dispersed to Sohagibarwa and established territories in 2021.
This colonization marks a positive step for the eastern extent of the tiger population within this landscape. Together with Chitwan, which has 128 tigers, and Parsa National Park, housing 41 tigers, this population block hosts a total of 213 tigers. As per the latest estimation, Valmiki Tiger Reserve is home to 54 tigers within its boundaries.
The Corridors of Terai Arc Landscape
In the Terai-Arc landscape, Corbett is linked to Pilibhit and Dudhwa via Nepal and a few fragmented connections within India, primarily through the Gola River corridor. Unfortunately, this corridor is on the brink of being lost and requires immediate attention for restoration. Suhelwa is entirely isolated from other protected areas within India and solely connected through habitats in Nepal. Proposed border roads for defense purposes between India, Nepal, and Bhutan must be strategically planned and managed to avoid becoming barriers to genetic exchange among tigers and other wildlife.
The tigers of Valmiki have been identified as a conservation priority due to their genetic distinctiveness and vulnerability. The connectivity of this tiger reserve with Nepal’s Chitwan National Park remains crucial, as it sustains the tiger population here. Most tiger reserves in this landscape are linked through forest patches in Nepal. Implementing mitigation measures at the critical junctions in this landscape can ensure the long-term movement of wild animals throughout this area. Browse our best tiger safari tours in India.
The Terai-Arc landscape, comprising a network of 15 protected areas spanning Nepal and India, harbors one of the largest tiger populations. The five tiger reserves situated on the Indian side, in conjunction with Nepal’s protected areas like Bardia, Chitwan, and Shuklaphanta, serve as source populations for areas with lower tiger occupancy. Conservation efforts at the level of these protected areas, coupled with bolstering corridor connectivity and enhancing protection measures, will establish connectivity for the unrestricted movement of large wildlife. This facilitates genetic exchange within the landscape, fostering healthy tiger populations across all forested areas.