The Bengal Tiger


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Categories : Wildlife

The Bengal tiger is a tiger from a specific population of the Panthera tigris tigris subspecies that is native to the Indian subcontinent.[3] It is threatened by poachingloss, and fragmentation of habitat, and was estimated at comprising fewer than 2,500 wild individuals by 2011. None of the Tiger Conservation Landscapes within its range is considered large enough to support an effective population of more than 250 adult individuals.[1] India‘s tiger population was estimated at 1,706–1,909 individuals in 2010.[4] By 2018, the population had increased to an estimated 2,603–3,346 individuals.[5] Around 300–500 tigers are estimated in Bangladesh, 220–274 tigers in Nepal and 103 tigers in Bhutan.[1][6][7]

The tiger is estimated to be present in the Indian subcontinent since the Late Pleistocene, for about 12,000 to 16,500 years.[8][9][10]

The Bengal tiger ranks among the biggest wild cats alive today.[2][11] It is considered to belong to the world’s charismatic megafauna.[12] It is the national animal of both India and Bangladesh.[13] It used to be called Royal Bengal tiger.[14]

TAXONOMY

.[19] Felis tigris was the scientific name used by Carl Linnaeus in 1758 for the tiger.[15] 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.[16]

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.[17] 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.[18] The extinct and living tiger populations in continental Asia have been subsumed to P. t. tigris since the revision of felid taxonomy in 2017.[3]

Results of a genetic analysis of 32 tiger samples indicate that the Bengal tiger samples grouped into a different monophyletic clade than the Siberian tiger samples

GENETIC ANCESTORY

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.[20] 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.[9]

CHARACERTISTICS

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 of the tiger, which is reported in the wild from time to time in Assam, Bengal, Bihar, and especially from the former State of Rewa. However, it is not to be mistaken as an occurrence of albinism. In fact, there is only one fully authenticated case of a true albino tiger, and none of black tigers, with the possible exception of one dead specimen examined in Chittagong in 1846.[21]

Males and females have an average total length of 270 to 310 cm (110 to 120 in) and 240 to 265 cm (94 to 104 in) respectively, including a tail of 85 to 110 cm (33 to 43 in) long.[2][22] They typically range 90 to 110 cm (35 to 43 in) in height at the shoulders.[22] The standard weight of males ranges from 175 to 260 kg (386 to 573 lb), while that of the females ranges from 100 to 160 kg (220 to 350 lb).[2][22] The smallest recorded weights for Bengal tigers are from the Bangladesh Sundarbans, where adult females are 75 to 80 kg (165 to 176 lb).[23]

The tiger has exceptionally stout teeth. Its canines are 7.5 to 10 cm (3.0 to 3.9 in) long and thus the longest among all cats.[24] The greatest length of its skull is 332 to 376 mm (13.1 to 14.8 in).[17]

BODY WEIGHT

Bengal tigers weigh up to 325 kg (717 lb), and reach a head and body length of 320 cm (130 in).[24] Several scientists indicated that adult male Bengal tigers from the Terai in Nepal and Bhutan, and Assam, Uttarakhand and West Bengal in north India consistently attain more than 227 kg (500 lb) of body weight. Seven adult males captured in Chitwan National Park in the early 1970s had an average weight of 235 kg (518 lb) ranging from 200 to 261 kg (441 to 575 lb), and that of the females was 140 kg (310 lb) ranging from 116 to 164 kg (256 to 362 lb).[25] Thus, the Bengal tiger rivals the Siberian tiger in average weight.[26] In addition, the record for the greatest length of a tiger skull was an “over the bone” length of 16.25 in (413 mm); this tiger was shot in the vicinity of Nagina in northern India.[27]

Three tigresses from the Bangladesh Sundarbans had a mean weight of 76.7 kg (169 lb). The oldest female weighed 75 kg (165 lb) 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.[28]

RECORDS

Two tigers shot in Kumaon District and near Oude at the end of the 19th century allegedly measured more than 12 ft (366 cm). 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’.[29] In the beginning of the 20th century, a male tiger was shot in central India with a head and body length of 221 cm (87 in) between pegs, a chest girth of 150 cm (59 in), a shoulder height of 109 cm (43 in) and a tail length of 81 cm (32 in), which was perhaps bitten off by a rival male. This specimen could not be weighed, but it was calculated to weigh no less than 272 kg (600 lb).[30] A male weighing 259 kg (570 lb) was shot in northern India in the 1930s.[27] In 1980 and 1984, scientists captured and tagged two male tigers in Chitwan National Park that weighed more than 270 kg (595 lb).[31] The heaviest wild tiger was possibly a huge male killed in 1967 at the foothills of the Himalayas. It weighed 388.7 kg (857 lb) after eating a buffalo calf, and measured 323 cm (127 in) in total length between pegs, and 338 cm (133 in) over curves. Without eating the calf beforehand, it would have likely weighed at least 324.3 kilograms (715 lb). This specimen is on exhibition in the Mammals Hall of the Smithsonian Institution.[32]

DISTRIBUTION AND HABITAT

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 ybp 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.[33] The tiger probably arrived too late in southern India to colonise Sri Lanka, which earlier had been connected to India by a land bridge.[16]

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.[9][34] In the Indian subcontinent, tigers inhabit tropical moist evergreen foreststropical dry forests, tropical and subtropical moist deciduous forestsmangroves, subtropical and temperate upland forests, and alluvial grasslands. 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. Today, 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 (TCUs) RajajiCorbettBardiaBanke, and the transboundary TCUs ChitwanParsaValmikiDudhwaKailali and ShuklaphantaKishanpur. Tiger densities in these TCUs are high, in part because of the extraordinary biomass of ungulate prey.[35]

The tigers in the Sundarbans in India and Bangladesh are the only ones in the world inhabiting mangrove forests.[4] The population in the Indian Sundarbans was estimated as 86-90 individuals in 2018.[5]

HUNTING AND DIET

The tiger is a carnivore. It prefers hunting large ungulates such as chitalsambargaur, and to a lesser extent also barasinghawater buffalonilgaiserow and takin. Among the medium-sized prey species it frequently kills wild boar, and occasionally hog deerIndian muntjac and grey langur. Small prey species such as porcupineshares and peafowl form a very small part in its diet. Because of the encroachment of humans into tiger habitat, it also preys on domestic

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