Bengal tiger
The Bengal tiger is a population of the Panthera tigris tigris subspecies. It ranks among the largest of wild cats. It is distributed from India, southern Nepal, Bangladesh, Bhutan to Southwestern China. Its historical range extended to the Indus Basin until the early 19th century, and it is thought to have been present in the Indian subcontinent since the Late Pleistocene about 12,000 to 16,500 years ago. It is threatened by poaching, habitat loss and habitat fragmentation.
As of 2022, the Bengal tiger population was estimated at 3,167–3,682 individuals in India, 316–355 individuals in Nepal, 131 individuals in Bhutan and around 125 individuals in Bangladesh. It is the national animal of India.
Taxonomy
Felis tigris was the scientific name used by Carl Linnaeus in 1758 for the tiger. It was subordinated to the genus Panthera by Reginald Innes Pocock in 1929. Bengal is the traditional type locality of the species and the nominate subspecies Panthera tigris tigris.The validity of several tiger subspecies in continental Asia was questioned in 1999. Morphologically, tigers from different regions vary little, and gene flow between populations in those regions is considered to have been possible during the Pleistocene. Therefore, it was proposed to recognise only two subspecies as valid, namely P. t. tigris in mainland Asia, and P. t. sondaica in the Greater Sunda Islands and possibly in Sundaland. The nominate subspecies P. t. tigris constitutes two clades: the northern clade comprises the Siberian and Caspian tiger populations, and the southern clade all remaining continental tiger populations. The extinct and living tiger populations in continental Asia have been subsumed to P. t. tigris since the revision of felid taxonomy in 2017.
Phylogeny
Results of a genetic analysis of 32 tiger samples indicate that the Bengal tiger samples grouped into a different clade than the Siberian tiger samples.Genetic ancestry
The Bengal tiger is defined by three distinct mitochondrial nucleotide sites and 12 unique microsatellite alleles. The pattern of genetic variation in the Bengal tiger corresponds to the premise that it arrived in India approximately 12,000 years ago. This is consistent with the lack of tiger fossils from the Indian subcontinent prior to the late Pleistocene, and the absence of tigers from Sri Lanka, which was separated from the subcontinent by rising sea levels in the early Holocene.Characteristics
The Bengal tiger's coat is yellow to light orange, with stripes ranging from dark brown to black; the belly and the interior parts of the limbs are white, and the tail is orange with black rings. The white tiger is a recessive mutant, which is reported in the wild from time to time in Assam, Bengal, Bihar and especially in the former State of Rewa. However, it is not an occurrence of albinism. In fact, only one fully authenticated case of a true albino tiger is known, and there are no confirmed cases of black tigers, except for a possible specimen examined in Chittagong in 1846. Fourteen Bengal tiger skins in the collection of the Natural History Museum, London have 21–29 stripes.Another recessive mutant is the golden tiger that has a pale golden fur with red-brown stripes. The mutants are very rare in nature.
The greatest skull length of a tiger is in males and in females. It has exceptionally stout teeth. Its canines are long and thus the longest among all cats.
Body weight and size
The Bengal tiger ranks among the biggest wild cats alive.Males and female Bengal tigers in Panna Tiger Reserve reach a head-to-body length of and respectively, including a tail about long. Total length ranges from for male tigers and for female tigers. They typically range from in shoulder height.
Subadult males weigh between and reach when adult; subadult females weigh and reach between when adult. In central India, 42 adult male Bengal tigers weighed on average with a range of ; their total length was with a range of, and their average shoulder height was ; 39 adult female Bengal tigers weighed an average of with a maximum of and an average total length of ranging from.
Several scientists indicated that adult male Bengal tigers in the Terai consistently attain more than of body weight. Seven adult males captured in Chitwan National Park in the early 1970s had an average weight of ranging from, and that of the females averaged ranging from. Two male tigers captured in Chitwan National Park in the 1980s exceeded weights of and are the largest free ranging tigers reported to date.
The smallest recorded weights for Bengal tigers are from the Bangladesh Sundarbans, where adult females weigh.
Three tigresses from the Bangladesh Sundarbans had a mean weight of. The oldest female weighed and was in a relatively poor condition at the time of capture. Their skulls and body weights were distinct from those of tigers in other habitats, indicating that they may have adapted to the unique conditions of the mangrove habitat. Their small sizes are probably due to a combination of intense intraspecific competition and small size of prey available to tigers in the Sundarbans, compared to the larger deer and other prey available to tigers in other parts.
The very large "Leeds Tiger" on display at Leeds City Museum, shot in 1860 near Mussoorie, had a body length of at death. Two tigers shot in Kumaon District and near Oude at the end of the 19th century allegedly measured more than. But at the time, sportsmen had not yet adopted a standard system of measurement; some measured 'between the pegs' while others measured 'over the curves'. The greatest length of a tiger skull measured "over the bone"; this one was shot in the vicinity of Nagina in northern India.
In the beginning of the 20th century, a male tiger was shot in central India with a head and body length of between pegs, a chest girth of, a shoulder height of and a tail length of, which was perhaps bitten off by a rival male. This specimen could not be weighed, but it was estimated to weigh about. A male weighing was shot in northern India in the 1930s. A male tiger shot in Nepal weighed and measured 'over the curves'.
The heaviest wild tiger was possibly a male killed in 1967 in the foothills of the Himalayas that measured between pegs and over curves; it weighed after eating a buffalo calf. Without eating the calf, it would have likely weighed about. In the Central Provinces of India, a male tiger shot weighed and measured.
The Bengal tiger rivals the Siberian tiger in average weight.
Distribution and habitat
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. The modern tiger inhabits India, Bangladesh, Nepal, Bhutan, and southwestern China.It is estimated to have been present in the Indian subcontinent since the Late Pleistocene, for about 12,000 to 16,500 years.
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 tiger probably arrived too late in southern India to colonise Sri Lanka, which earlier had been connected to India by a land bridge.
Results of a phylogeographic study using 134 samples from tigers across the global range suggest that the historical northeastern distribution limit of the Bengal tiger is the region in the Chittagong Hills and Brahmaputra River basin, bordering the historical range of the Indochinese tiger.
In the Indian subcontinent, Bengal tigers inhabit tropical moist evergreen forests, tropical dry forests, tropical and subtropical moist deciduous forests, mangroves, subtropical and temperate upland forests, and alluvial grasslands. 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. The best examples of this habitat type are limited to a few blocks at the base of the outer foothills of the Himalayas including the Tiger Conservation Units Rajaji-Corbett-Pilibhit, Bardia-Banke, and the transboundary TCUs Chitwan-Parsa-Valmiki, Dudhwa-Kailali and Shuklaphanta-Kishanpur. Tiger densities in these TCUs are high, in part because of the extraordinary biomass of ungulate prey.
In Pakistan, Khairpur was the last stronghold of the tiger by the late 19th century; the last individuals were shot in 1906 in Bahawalpur in the Indus Riverine jungles.
India
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. Camera traps are now being used in many sites.Good tiger habitats in subtropical and temperate forests include the Tiger Conservation Units Manas-Namdapha. TCUs in tropical dry forest include Hazaribag Wildlife Sanctuary, Nagarjunsagar-Srisailam Tiger Reserve, Kanha-Indravati corridor, Orissa dry forests, Panna National Park, Melghat Tiger Reserve and Ratapani Tiger Reserve. The TCUs in tropical moist deciduous forest are probably some of the most productive habitats for tigers and their prey, and include Kaziranga-Meghalaya, Kanha-Pench, Simlipal and Indravati Tiger Reserves. The TCUs in tropical moist evergreen forests represent the less common tiger habitats, being largely limited to the upland areas and wetter parts of the Western Ghats, and include the tiger reserves of Periyar, Kalakad-Mundathurai, Bandipur and Parambikulam Wildlife Sanctuary.
During a tiger census in 2008, camera trap and sign surveys using GIS were employed to estimate site-specific densities of tiger, co-predators and prey. Based on the result of these surveys, the total tiger population was estimated at 1,411 individuals ranging from 1,165 to 1,657 adult and sub-adult tigers of more than 1.5 years of age. Across India, six landscape complexes were surveyed that host tigers and have the potential to be connected. These landscapes comprise the following:
- in the Sivaliks–Gangetic flood plain landscape there are six populations with an estimated population size of 259 to 335 individuals in an area of of forested habitats, which are located in Rajaji and Corbett National Parks, in the connected habitats of Dudhwa-Kheri-Pilibhit, in Suhelwa Tiger Reserve, in Sohagi Barwa Sanctuary and in Valmiki National Park;
- in the Central Indian highlands there are 17 populations with an estimated population size of 437 to 661 individuals in an area of of forested habitats, which are located in the landscapes of Kanha-Pench, Satpura-Melghat, Sanjay-Palamau, Navegaon-Indravati; isolated populations are supported in the tiger reserves of Bandhavgarh, Tadoba, Simlipal and the national parks of Panna, Ranthambore–Kuno–Palpur–Madhav and Saranda;
- in the Eastern Ghats landscape there is a single population with an estimated population size of 49 to 57 individuals in a habitat in three separate forest blocks located in the Srivenkateshwara National Park, Nagarjunasagar Tiger Reserve and the adjacent proposed Gundla Brahmeshwara National Park, and forest patches in the tehsils of Kanigiri, Badvel, Udayagiri and Giddalur;
- in the Western Ghats landscape there are seven populations with an estimated population size of 336 to 487 individuals in a forested area of in three major landscape units Periyar-Kalakad-Mundathurai, Bandipur-Parambikulam-Sathyamangalam-Mudumalai-Anamalai-Mukurthi and Anshi-Kudremukh-Dandeli;
- in the Brahmaputra flood plains and northeastern hills tigers live in an area of in several patchy and fragmented forests;
- in the Sundarbans National Park tigers live in about of mangrove forest.
Ranthambore National Park hosts India's westernmost tiger population. The Dangs' Forest in southeastern Gujarat is potential tiger habitat.
In May 2018, a tiger was recorded in Sahyadri Tiger Reserve for the first time in eight years.
In February 2019, a tiger was sighted in Gujarat's Lunavada area in Mahisagar district, and found dead shortly afterwards. Officials assumed that it originated in Ratapani Tiger Reserve and travelled about over two years. It probably died of starvation. In May 2019, camera traps recorded tigers in Mhadei Wildlife Sanctuary and Bhagwan Mahaveer Sanctuary and Mollem National Park, the first records in Goa since 2013.
The tigers in the Sundarbans in India and Bangladesh are the only ones in the world inhabiting mangrove forests. The population in the Indian Sundarbans was estimated as 86–90 individuals in 2018.
As of 2014, the Indian tiger population was estimated to range over an area of and number 2,226 adult and subadult tigers older than one year. About 585 tigers were present in the Western Ghats, where Radhanagari and Sahyadri Tiger Reserves were newly established. The largest population resided in Corbett Tiger Reserve with about 215 tigers. The Central Indian tiger population is fragmented and depends on wildlife corridors that facilitate connectivity between protected areas. By 2018, the population had increased to an estimated 2,603–3,346 individuals. As of 2022, the Indian population was estimated to comprise 3,167–3,682 individuals.