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Location India, West Bengal
Central coordinates 88o 58.35' East  22o 10.77' North
IBA criteria A1
Area 133,010 ha
Altitude 0 - 5m
Year of IBA assessment 2004

Bombay Natural History Society

Site description The Sundarban is the largest delta covered with mangrove forests and vast saline mud flats in the world. It got the name from the mangrove plant locally known as Sundari Heritiera minor. The Sundarban stretches from the Hooghly (India) on the west to the Meghna (Bangladesh) in the east, both of which are major streams of the River Ganga. It spreads over the southern part of three districts, namely 24-Parganas (India), Khulna and Backarganj (Bangladesh). The boundary of Sundarban within West Bengal is demarcated by the Raimangal and Hooghly rivers in the East and West respectively, and the Bay of Bengal in the south. The northern limit cannot be clearly defined due to the progressive reclamation of land. The Sundarban covers an area of 9,63,000 ha, of which 2,58,500 ha is demarcated as the Sundarban Tiger Reserve and 1,33,000 as the National Park (core area). Sajnakhali Wildlife Sanctuary (36,234 ha) lies within the buffer zone, to the north of Netidhopani and Chadkhali forest blocks. There are two small sanctuaries within the Biosphere Reserve: the 583 ha Halliday Island Wildlife Sanctuary, and the 3,885 ha Lothian Island Wildlife Sanctuary. Sunderban is the largest mangrove forest, with perhaps the largest tiger population in the world. It is a World Heritage Site and Biosphere Reserve, both in India and Bangladesh. It is also proposed as a Ramsar site. This World Heritage site is known for its rich biodiversity, especially fish, crustaceans, reptiles and birds. The total area of the IBA extends over 4,26,200 ha, of which 2,32,000 ha is under mangrove forest and the remaining is under water (Mukherjee 1975). As reported earlier, Heritiera minor, locally known as Sundari (Jain and Sastry 1983) is a predominant feature of the IBA. Champion (1936) classified the Sundarban as Moist Tropical Seral Forest, comprising beach forest and tidal forests. Characteristic species include Rhizophora spp., Bruguiera gymnorhiza, Ceriops sp., and Avicennia officinalis. Heritiera minor is scattered over areas of higher elevation, along with Sonneratia apetala, Excoecaria agallocha, and Phoenix paludosa. Low mangrove forest (3-6 m high) occurs between Matla and Muriganga, to the west of the National Park and Tiger Reserve. This area is devoid of fresh water because its rivers are cut off from the ramifications of the Hooghly in the north. The soft mud of the intertidal zone supports a dense forest, very similar in composition to salt-water Heritiera forest. Various trees and other plants were introduced, including some exotics.

Key Biodiversity 

AVIFAUNA: Sanyal (2002) identified 163 species of birds from Sunderban but recently, Sujan Chatterjee (in litt. 2003) has listed 219 species. Although the whole of the Sunderban mangrove is a bird watcher’s paradise, Sajnakhali Wildlife Sanctuary is best known for its bird life. Mukherjee (1959) found 16 species in a breeding colony, including Darter Anhinga melanogaster and Black-necked Stork Ephippiorhynchus asiaticus (both presently Near Threatened). In India, Sunderban in the most important site for the Vulnerable Masked Finfoot Heliopais personata. It is difficult to estimate the total number of this elusive bird, but it is fairly common in suitable areas. Earlier, Greater Adjutant Leptoptilos dubius was commonly seen but now sightings are rare due to drastic decline in its numbers. Another uncommon species is the Spoon-billed Sandpiper Eurynorhynchus pygmeus, which is regularly reported from this site. As can be expected, Sunderban is famous for its waterbirds and water-dependent birds, such as the kingfishers. Out of the 12 kingfisher species found in India, six are found in this IBA. They are the Common Alcedo atthis, Brown-winged Halcyon amauroptera, Stork-billed H. capensis, Ruddy H. coromanda, White-throated H. smyrnensis, Black-capped H. pileata, Collared Todiramphus chloris and Pied Ceryle rudis Kingfishers. About 30 species of small waders (sandpipers, stints, plovers, curlews, etc.) and nine species of gulls and terns are found here. Sunderban is one of two sites where the Mangrove Whistler Pachycephala grisola is definitely found. This species is not considered threatened by BirdLife International (2001) as it is widely distributed in south and southeast Asia but its narrow, ribbon-like habitat along the coasts, that is under tremendous human pressure all over Asia, would put this species at risk in future. Incidentally, this is the only bird species that is entirely restricted to mangroves (Ali and Ripley, 1987, Grimmett et al. 1998). The vast Sunderban mangroves and mud flats host hundreds of thousands of waterbirds, especially waders but as we do not have species-wise detailed information, we have not listed this site under any A4 criteria. This site is selected only on the basis of presence of globally threatened species (A1 criteria).

OTHER KEY FAUNA: Although seldom seem, the Tiger Panthera tigris is the star attraction of Sunderban. Sunderban also has the largest population of the Estuarine Crocodile Crocodylus porosus. A hundred years ago the Sundarban Forests were the home of many wild animals, including the Javan Rhinoceros Rhinoceros sondaicus, Swamp Deer Cervus duvauceli, Chital Axis axis, Wild Boar Sus scrofa, Rhesus Macaque Macaca mullata, Fishing Cat Felis viverrina, and Wild Buffalo Bubalus arnee. It is said that Barking Deer Muntiacus muntjak existed on these swamp islands, but it has not been recorded in recent years from the Sundarban Forests that lie in West Bengal.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Swamp Francolin Francolinus gularis resident  2004  present  A1  Vulnerable 
Baer's Pochard Aythya baeri winter  2004  present  A1  Critically Endangered 
Lesser Adjutant Leptoptilos javanicus resident  2004  present  A1  Vulnerable 
Greater Adjutant Leptoptilos dubius non-breeding  2004  present  A1  Endangered 
Pallas's Fish-eagle Haliaeetus leucoryphus resident  2004  present  A1  Vulnerable 
Greater Spotted Eagle Clanga clanga winter  2004  present  A1  Vulnerable 
Masked Finfoot Heliopais personatus resident  2004  present  A1  Endangered 
Spoon-billed Sandpiper Calidris pygmaea winter  2004  present  A1  Critically Endangered 

IBA Monitoring

2012 low favourable medium
Medium - based upon reliable but incomplete / partially representative data

No known threats no known threats happening now whole area/population (>90%) no or imperceptible deterioration low

Forest   0 0 good (> 90%) good (> 90%) favourable

Whole area of site (>90%) covered by appropriate conservation designation  A comprehensive and appropriate management plan exists that aims to maintain or improve the populations of qualifying bird species  Some limited conservation initiatives are in place  medium 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Sundarbans National Park 133,010 is identical to site 133,010  
Sundarbans National Park World Heritage Site 133,010 is identical to site 133,010  
Sunderban UNESCO-MAB Biosphere Reserve 963,000 protected area contains site 133,010  


IUCN habitat Habitat detail Extent (% of site)
Forest   -
Coastline   -
Wetlands (inland)   -
Artificial - terrestrial   -

Land use

Land-use Extent (% of site)
fisheries/aquaculture -
Notes: Fisheries
nature conservation and research -
Notes: Nature Conservation

Acknowledgements Key contributors: Sujan Chatterjee, Kushal Mukherjee and the IBA team.


Ali, S. and Ripley, S. D. (1987) Compact Edition of the Handbook of the Birds of India and Pakistan. Oxford University Press, New Delhi.

BirdLife International (2001) Threatened Birds of Asia: The BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.

Champion, H. G. (1936) A preliminary survey of the forest types of India and Burma. Indian Forest Records (New Series) 1: 1-286.

Grimmett, R., Inskipp, C. and Inskipp, T. (1998) Birds of the Indian Subcontinent. Christopher Helm (Publishers) Ltd., London, U.K.

Jain, S. K. and Sastry, A. R. K. (1983) Botany of some tiger habitats in India. Botanical Survey of India, Howrah. Pp. 40-44.

Mukherjee, A. K. (1959) Pakhirala, Sajnakhali - an introduction to a bird sanctuary in the Sundarbans. J. Bombay Nat. Hist. Soc. 30: 161-165.

Mukherjee, A. K. (1975) The Sundarban of India and its biota. J. Bombay Nat. Hist. Soc. 72: 1-20.

Sanyal, P. (2002) Sunderbans Biosphere Reserve. In Traditional Ecological Knowledge for Managing Biosphere Reserves in South and Central Asia. Eds. Ramakrishan, P., Rai, R. K.

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Sundarbans Biosphere Reserve (National Park). Downloaded from on 24/10/2016

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