The Indian Sundarbans Has Been a UNESCO World Heritage Site Since 1987, Had 100 Tigers Photographed in 2022, and Won Approval in 2025 to Enlarge Its Tiger Reserve to 3,629.57 Square Kilometres

The Indian Sundarbans is a mangrove forest in the Ganges delta of West Bengal that UNESCO listed as a World Heritage Site in 1987, and the national tiger survey of 2022 photographed 100 different tigers in it. The listed property, Sundarbans National Park, covers 133,010 hectares of forest and tidal waterways. It sits inside a tiger reserve, a biosphere reserve and a Ramsar wetland, each with its own boundary and date.

What UNESCO wrote in 1987

UNESCO’s statement of Outstanding Universal Value rests on two criteria, (ix) and (x). Under (ix) it calls the Sundarbans the largest area of mangrove forest in the world and “the only one that is inhabited by the tiger”. It says tides keep reshaping the land, with erosion stronger along the estuaries and silt deposited along the inner waterways, and that the forest works as a nursery for marine life and a buffer against cyclones. Under (x) it records some 78 mangrove species and calls the site the richest mangrove forest in the world.

UNESCO gives the area as 133,010 hectares, about 55 per cent forest and 45 per cent tidal rivers, creeks, canals and river mouths. Bangladesh’s part of the forest was listed separately in 1997, according to a UNESCO news item of 4 June 2020.

The sources divide the whole forest between the two countries differently. UNESCO’s text puts about 34 per cent of the mangrove area in India. The National Tiger Conservation Authority’s 2022 report says 42 per cent of the mangrove habitat lies in Indian territory. The West Bengal Department of Sundarban Affairs gives the Indian reserved forest as 4,200 sq km of a forest of about 10,200 sq km.

Seventy-eight mangrove species, and the tree the delta may be named after

The Sundarban Tiger Reserve’s website says the name Sundarban is believed to come from sundari, the local name of the mangrove tree Heritiera fomes. The reserve counts more than 300 plant species and names over two dozen mangroves and close associates, among them garjan (Rhizophora apiculata), genwa (Excoecaria agallocha), keora (Sonneratia apetala), kankra (Bruguiera gymnorhiza), the palm hental (Phoenix paludosa) and the nipa palm golpata (Nypa fruticans). UNESCO’s count of 78 mangrove species is higher than the reserve’s list, and neither source says how its figure was drawn up.

The reserve describes how these plants live in salt water. Their leaves are leathery and push out extra salt, their roots include stilt roots and pneumatophores (roots that rise above the mud to take in air, because the soil holds little oxygen), and their seeds germinate while still on the tree. The Ramsar information sheet says the Indian Sundarban holds over 60 per cent of India’s mangrove forest area and 90 per cent of its mangrove species.

Tigers that swim for their food

UNESCO says the Sundarbans tigers live an almost amphibious life. They swim long distances and eat fish, crabs and water monitor lizards. The 2022 national report describes them as smaller in size and morphologically different from the tigers of peninsular India, and names spotted deer, wild pig and rhesus macaque as their main prey.

UNESCO also records Irrawaddy and Ganges river dolphins, king cobras and the northern river terrapin, which it says was once believed extinct, and it says the site provides nesting grounds for olive ridley, green and hawksbill turtles.

What the cameras counted in 2022

The 2022 national survey detected tigers in 41 grid cells of the Sundarbans and photographed 100 individual tigers older than a year, the NTCA and the Wildlife Institute of India report. The reserve’s own tiger page gives the detail. In its account, 713 camera stations ran for 25,264 trap nights and produced 849 tiger photographs, 81 tigers were photographed in the reserve and 20 in the adjoining South 24 Parganas forests, and one tiger appeared in both. It gives a population estimate of 101 (standard error 10). Down To Earth, citing the latest census, reports the split as 80 inside the reserve and 21 outside.

The same page lists the estimate as 76 in 2014, 88 in 2018 and 101 in 2022. It puts tiger density at 4.27 per 100 sq km over an occupied area of 1,895 sq km, and the sex ratio, corrected for detection, at two females to every male. How camera-trap counting works is set out in how India counts its tigers and lions, and the national totals are in India’s three tiger numbers.

West Bengal’s forest minister told PTI when the 2022 report came out that the figure of 100 did not reflect reality and should be higher. The state’s Chief Wildlife Warden told the agency that a camera-trap count of 100 was bound to fall short of the true population.

Fieldwork for the next count began on 27 November 2025, when forest officials started installing 1,484 cameras over about 4,100 sq km, including the Matla, Raidighi and Ramganga ranges, PTI reported. The reserve’s tiger page still lists 2022 as its latest cycle.

Four designations on one forest

The Sundarban Tiger Reserve took effect on 23 December 1973 as one of the first nine reserves under Project Tiger, according to its website. It gives the area as 2,584.89 sq km. That is the 1,330.10 sq km national park, the 362.40 sq km Sajnekhali Wildlife Sanctuary and 892.43 sq km of reserve forest. A core zone of 1,699.62 sq km was notified in 2007 and a buffer of 885.27 sq km in 2009.

On 19 August 2025 the standing committee of the National Board for Wildlife approved adding 1,044.68 sq km from the Matla, Raidighi and Ramganga ranges of South 24 Parganas, Down To Earth reported on 22 August. That takes the reserve to 3,629.57 sq km, second in India to Nagarjunasagar-Srisailam in Andhra Pradesh at 3,727.82 sq km.

The Government of India declared a Sundarban Biosphere Reserve of 9,630 sq km in 1989, the state’s Department of Sundarban Affairs says, and UNESCO admitted it to its world network in November 2001, a date UNESCO’s own text confirms. On 30 January 2019 the Indian Sundarban became Ramsar site number 2370, with an area of 423,000 hectares. It is one of the wetlands in the tally that reached 103 on 15 October 2026, covered in tuput’s piece on India’s Ramsar list.

Staffing is the shortfall the officials themselves name. The reserve’s website lists 50 per cent vacancies in front-line staff among its challenges. A forest official told Down To Earth the reserve had hardly 40 per cent of its approved manpower and that the state notification for the enlarged area was still awaited.

Fences, honey permits and the villages at the edge

UNESCO’s news item of 19 August 2020 gives 4.5 million as the number of people living in the Indian Sundarbans. Its statement of integrity records that tigers killed an average of 45 people a year from 1975 to 1982, and says this has caused conflict with local people who use the adjacent reserve for honey, firewood and fishing. In a summary given to UNESCO for its 2012 best-practice review, the Indian government says the site borders 25 densely populated villages on its north-western edge.

That summary lists what was tried. Forestry operations stopped, permits for hental and golpata ended, freshwater ponds were dug, and human face masks and clay models fitted with electric energisers were set up. The summary says none of these had conclusively proved effective, and that nylon-net fencing along the forest fringe had. By then 54 km of 70 km was fenced, and the state reported a downward trend in killings and strayings. The mesh is 4 by 4 inches so that deer are not strangled, and because tigers can clear an 8-foot fence, concrete and bamboo posts were used to reach 10 to 12 feet.

The reserve’s website now lists nylon-net fences of about 21 km in the western national park range, 35 km in the Sajnekhali range and 40 km in the Basirhat range. A forest guard checks them daily with a member of the local joint forest management committee, the beat officer weekly and the range officer every 15 days. After Cyclone Amphan made landfall on 20 May 2020, UNESCO said around 80 per cent of the fencing was damaged, and its Rapid Response Facility funded WWF-India to replace at least 50 km of nylon net. The storm’s forecast and toll are in tuput’s article on cyclone warning in India.

Honey and beeswax are gathered in April and May under permits the reserve issues every year, and the honey goes to the reserve’s godowns and then to the West Bengal Forest Development Corporation. The Better India (12 January 2026) relays a WWF report that puts the toll of what it calls blood honey at about five collectors a year, around 34 per cent of conflict deaths. WWF-India and the Sundarbans Biosphere Reserve directorate then asked five honey collectors to keep apiary boxes in fenced areas instead of seeking wild honey. The daily yield per box was nearly double the wild yield, and three cooperatives now sell the honey as Bonphool Wild Honey.

The same article says WWF-India has trained 99 local volunteers, called prokriti bondhus, in 46 villages since June 2022. They have carried out 75 wildlife rescues and helped officials in 10 tiger-straying incidents.

Sea level and erosion in the published record

UNESCO’s integrity text says salinity in the Indian Sundarbans is influenced by upstream diversion of up to 40 per cent of the Ganges’s dry-season flow, and that the effects are not clearly understood. The NTCA’s 2022 report says the region is open to sea-level rise and submergence and gains and loses land every year.

The Ministry of Earth Sciences’ National Centre for Coastal Research assessed shorelines from 1990 to 2016 and found 63 per cent of West Bengal’s 534.35 km coast eroding, with 99.05 sq km of land lost to erosion, the most of any state. Those figures cover the whole state coast, not the Sundarbans alone.

A modelling study by researchers at Jadavpur University, University College London and the University of East Anglia, published in Science of the Total Environment in 2023, looked at the Indian Sundarbans to 2100 under a range of sea-level scenarios. It found the mangroves could lose between 42 and 80 per cent of their current area if current management continues, and that managed realignment could offset the losses at the cost of productive land and the migration of the human population.