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Site description (2004 baseline):

This site includes two reserve forests, Subansiri in Dhemaji district and Dulung in Lakhimpur district in northeastern Assam. The river Subansiri passes through the middle of the IBA, while its tributaries Pavo, Geruka, Dirpai and Dulung drain other parts of the site. It is here that the Subansiri River debouches into the plains, forming a broad braided stretch of aquatic and terrestrial habitats. The terrain of the site is hilly, as it covers foothills of the Eastern Himalayas. Small flat areas occur along the southern portion. The higher parts of Subansiri Reserve Forest are more than 300 m above msl. The site is known for wildlife, especially Asian Elephant Elephas maximus and birds. There was an excellent patch of terai grassland in Dirpai area of Subansiri RF, where the Bengal Florican Houbaropsis bengalensis and the Swamp Francolin Francolinus gularis used to occur. While the call of the francolins is still heard, the florican has become sporadic. This is mainly due to encroachment and settlements in its grassland habitat. There is also a record of the Chestnut-breasted or Red-breasted Hill Partridge Arborophila mandellii from the higher areas of Subansiri RF (Choudhury 2000). The entire area is clothed with thick, lush Tropical Evergreen and Semi-evergreen forests, with absolute habitat contiguity with Taley Valley Wildlife Sanctuary (IBA) of Arunachal Pradesh, across the river Subansiri.

AVIFAUNA: Subansiri is an extremely important habitat for bird life. More than 200 bird species have been identified, some of them rare (A. U. Choudhury pers. comm. 2003). This site represents Biome-9 (Indo- Chinese Tropical Moist Forests) but birds of other biomes (5, 7, 8, 11 and 12) are also found here, some species only in winter. Some of the important species noted are the Himalayan Griffon Gyps himalayensis, Rufous-breasted Blue Flycatcher Ficedula hodgsonii, Slaty Flycatcher F. tricolor, Ferruginous Flycatcher Muscicapa ferruginea, Chestnut-headed Tesia Tesia castaneocoronata, Grey-bellied Tesia T. cyaniventer, Blue-throated Barbet Megalaima asiatica, Bay Woodpecker Blythipicus pyrrhotis, Maroon Oriole Oriolus traillii, Black-naped Oriole O. tenuirostris, Grey Treepie Dendrocitta formosae, Black-winged Cuckoo Shrike Coracina melaschistos, White-throated Bulbul Alophoixus flaveolus, Black Bulbul Hypsipetes leucocephalus, Grey-winged Blackbird Turdus boulboul, Redheaded Babbler Stachyris ruficeps, Himalayan Golden-backed Woodpecker Dinopium shorii, Necklaced Laughingthrush Garrulax moniligerus, Black-gorgeted Laughingthrush G. pectoralis and Rufous-necked Laughingthrush G. ruficollis.

OTHER KEY FAUNA: Subansiri Reserve Forest has most of the major mammal species found in Tropical Evergreen and Semi-evergreen forests of Assam.

It has four species of primates, such as the Slow Loris Nycticebus coucang, Capped Langur Trachypithecus pileatus, Assamese Macaque Macaca assamensis and Rhesus Macaque M. mulatta.

Asiatic Black Bear Ursus thibetanus is perhaps the largest predator but is confined to higher altitudes. In the steamy jungles and tall grasslands, there are Tiger Panthera tigris, Leopard P. pardus, Clouded Leopard Neofelis nebulosa and Marbled Cat Pardofelis marmorata (Choudhury 1996). Gaur Bos frontalis, Serow Nemorhaedus sumatraensis, Sambar Cervus unicolor, and Barking Deer Muntiacus muntjak are the ungulates. Malayan Giant Squirrel Ratufa bicolor is quite common in closed canopy forest. The Gangetic River Dolphin Plantanista gangetica is usually found in the monsoon, while Common Otter Lutra lutra, and Smooth Indian Otter Lutrogale perspicillata are found throughout the year in undisturbed streams and rivers.

MAIN THREATS: Environmental impact of the Lower Subansiri Hydel Project; Encroachment; Illegal felling of trees; Poaching; Grazing.

India’s largest hydroelectric project (Siang project is yet to be commissioned) is being constructed here. Known as the Lower Subansiri Hydroelectric Project, its installed capacity will be 2000 MW. This is the most significant conservation issue that will affect the site. The central and state goverments have laid down certain conditions to minimize the damage to the biodiversity of the site. One of the conditions laid down by the Government of India is the declaration of adjacent forests as wildlife sanctuaries or national parks. Therefore, this IBA site may soon get sanctuary status. Owing to the very high biodiversity value of this proposed IBA, it is vital that a detailed bio-habitat analysis is undertaken by a reputed organization like the BNHS, before any decision can be taken with regard to the Lower Subansiri Hydroelectric Project. Such studies would need to focus on the presence and the likely impact on rare and endangered species of plants and animals and also on the impacts of wildlife on account of loss of riverine habitats such as sand banks, rivulets, denning and nesting sites and breeding grounds of aquatic fauna. A special study is required to assess the impact of the dam, reservoir and supporting infrastructure such as labour and housing colonies on the migration route of elephants (Saghal and Sharma 2002). According to the National Hydroelectric Power Corporation (NHPC), only 42 ha of Taley Valley WLS would be submerged by the reservoir. The fact is that the proposed reservoir would submerge a large primary forests of Taley RF and Panir RF in Arunachal Pradesh and Subansiri RF in Assam. These are vital forests for a large number of endangered species protected under the Indian Wildlife Protection Act (Choudhury 2002, Vagholikar and Ahmed 2003). The proposed submergence extends approximately 75 km upstream. Therefore, the impact on areas outside the Taley Valley WLS, including corridors and riverine patches, is likely to be as severe as the damage to the Sanctuary itself.

Key contributors: Anwaruddin Choudhury, Neeraj Vagholikar, Manju Menon and Bikul Goswami.

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Subansiri (India). Downloaded from https://datazone.birdlife.org/site/factsheet/subansiri-iba-india on 22/11/2024.