Its historical range covered the Indus River valley until the early 19th century, almost all of India, western Pakistan, southern Nepal, Bangladesh, Bhutan and southwestern China.

[18] Several scientists indicated that adult male Bengal tigers in the Terai consistently attain more than 227 kg (500 lb) of body weight.

[28] The Bengal tiger's historical range covered the Indus River valley until the early 19th century, almost all of India, western Pakistan, southern Nepal, Bangladesh, Bhutan, and southwestern China.

[29][30] In 1982, a sub-fossil right middle phalanx was found in a prehistoric midden near Kuruwita in Sri Lanka, which is dated to about 16,500 years ago and tentatively considered to be of a tiger.

Tigers appear to have arrived in Sri Lanka during a pluvial period, during which sea levels were depressed, evidently prior to the last glacial maximum about 20,000 years ago.

The latter habitat once covered a huge swath of grassland, riverine and moist semi-deciduous forests along the major river system of the Gangetic and Brahmaputra plains, but has now been largely converted to agricultural land or severely degraded.

[34] In the 20th century, Indian censuses of wild tigers relied on the individual identification of footprints known as pug marks – a method that has been criticised as deficient and inaccurate.

These landscapes comprise the following:[36] Manas-Namdapha, Orang-Laokhowa and Kaziranga-Meghalaya are Tiger Conservation Units in northeastern India, stretching over at least 14,500 km2 (5,600 sq mi) across several protected areas.

Information is lacking on many aspects of Sundarbans tiger ecology, including relative abundance, population status, spatial dynamics, habitat selection, life history characteristics, taxonomy, genetics, and disease.

[54] A rising sea-level due to climate change is projected to cause a severe loss of suitable habitat for this population in the following decades, around 50% by 2050 and 100% by 2070.

[61] Royal Manas and Jigme Singye Wangchuck National Parks form the largest contiguous tiger conservation area in Bhutan representing subtropical to alpine habitat types.

[67] The presence of the Bengal tiger in southeastern Tibet Autonomous Region, China was investigated in 1995 when the loss of livestock was high in Mêdog County due to a large predator.

[70] A camera trapping and interview survey during 2013–2018 in nine potential sites in Mêdog County revealed that only 1–3 non-resident individuals might be entering the area south of the Yarlung Tsangpo river, but only during the dry season from October to March.

[71] In early 2019, a Bengal tiger was photographed twice at an elevation of 2,000 m (6,600 ft) in a broadleaved forest in Yarlung Tsangpo Grand Canyon National Nature Reserve.

Resident adults of either sex maintain home ranges, confining their movements to definite habitats within which they satisfy their needs and those of their cubs, which include prey, water and shelter.

A male tiger keeps a large territory in order to include the home ranges of several females within its bounds, so that he may maintain mating rights with them.

[75] The Bengal tiger is a carnivore and prefers hunting large ungulates such as gaur, sambar, chital, barasingha, water buffalo, nilgai, serow and takin.

The nature of the tiger's hunting method and prey availability results in a "feast or famine" feeding style: they often consume 18–40 kg (40–88 lb) of meat at one time.

[90] In the 1960s, certain aspects of tiger behaviour at Kanha National Park indicated that the peak of sexual activity was from November to about February, with some mating probably occurring throughout the year.

[93] The most significant immediate threat to the existence of wild tiger populations is the illegal wildlife trade in poached skins and body parts between India, Nepal and China.

The governments of these countries have failed to implement adequate enforcement response, and wildlife crime remained a low priority in terms of political commitment and investment for years.

Each group of people has different motives for killing tigers, ranging from profit and excitement to safety concerns; and has access to the illegal wildlife trade in body parts.

For at least a thousand years, tiger bones have been an ingredient in traditional medicines that are prescribed as a muscle strengthener and treatment for rheumatism and body pain.

They are thought to have followed domestic livestock that wintered in the plains when they returned to the hills in the spring, and then being left without prey when the herds dispersed back to their respective villages.

The goals are to manage tigers as a single metapopulation, the dispersal of which between core refuges can help maintain genetic, demographic, and ecological integrity, and to ensure that species and habitat conservation becomes mainstreamed into the rural development agenda.

In Nepal a community-based tourism model has been developed with a strong emphasis on sharing benefits with local people and on the regeneration of degraded forests.

[128] In January 2008, the Government of India launched a dedicated anti-poaching force composed of experts from Indian police, forest officials and various other environmental agencies.

Since no lions have been transferred from Gujarat to Madhya Pradesh so far, it may be used as a sanctuary for the tiger instead where it could help keep down the leopard population that targets the main prey of reintroduced cheetahs.

[133] In July 1976, Billy Arjan Singh acquired a hand-reared tigress from Twycross Zoo in the United Kingdom, and reintroduced her to the wild in Dudhwa National Park with the permission of India's then Prime Minister Indira Gandhi.

[143][144] Stuart Bray, who had originally invested a large sum of money in the project, claimed that he and his wife, Li Quan, watched the film crew "[chase] the prey up against the fence and into the path of the tigers just for the sake of dramatic footage.