The Royal Bengal Tiger
The Bengal tiger (Panthera tigris tigris) is a tiger subspecies native to the Indian subcontinent that in 2010 has been classified as endangered by IUCN. The total population is estimated at fewer than 2,500 individuals with a decreasing trend, and none of the Tiger Conservation Landscapes within the Bengal tiger's range is large enough to support an effective population size of 250 adult individuals.[1]
The Bengal tiger is the most numerous tiger subspecies with populations estimated at 1,520–1,909 in India, 440 in Bangladesh, 124–229 in Nepal and 67–81 in Bhutan.[2][3][4][5]
Bengal is traditionally fixed as the typical locality for the binomial Panthera tigris, to which the British taxonomist Reginald Innes Pocock subordinated the Bengal tiger in 1929 under the trinomial Panthera tigris tigris.[6]
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 is white, and the tail is white with black rings.
Male Bengal tigers had a total length, including the tail, from 270 to 310 cm (110 to 120 in), while females range from 240 to 265 cm (94 to 104 in).[8] Tails are 85 to 110 cm (33 to 43 in) long, and height at the shoulders is 90 to 110 cm (35 to 43 in).[9] The head and body length of three males captured in Nagarahole National Park ranged from 189 to 204 cm (74 to 80 in), with a tail length of 100 to 107 cm (39 to 42 in), while a single female measured 161 cm (63 in), with a tail length of 87 cm (34 in).[10] The average weight of males is 221.2 kg (488 lb), while that of females is 139.7 kg (308 lb).[11]
Males captured in Chitwan National Park in the early 1970s had an average weight of 235 kg (520 lb) ranging from 200 to 261 kg (440 to 580 lb), and that of the females was 140 kg (310 lb) ranging from 116 to 164 kg (260 to 360 lb).[12] Males from the northern India are as large as Siberian tigers with a greatest length of skull of 332 to 376 mm (13.1 to 14.8 in).[13]
The white tiger is a recessive mutant of the Bengal tiger, which was reported in the wild from time to time in Assam, Bengal, Bihar and especially from the former State of Rewa. 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.
Two tigers shot in Kumaon and near Oude at the end of the 19th century allegedly measured more than 12 ft (370 cm). But at the time, sportsmen had not yet adopted a correct system of measurement, some measuring between pegs and others round the curves.[15]
In the beginning of the 20th century, a male Bengal tiger was shot in central India with a head and body length of 221 cm (87 in) measured between pegs, 150 cm (59 in) of chest girth, a shoulder height of 109 cm (43 in) and a tail of just 81 cm (32 in), 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).[16]
A heavy male weighing 570 lb (260 kg) was shot in northern India in the 1930s.[17] The heaviest known tiger was a huge male killed in 1967 that weighed 388.7 kg (857 lb) and measured 322 cm (127 in) in total length between the pegs, and 338 cm (133 in) over curves. This specimen is on exhibition in the Mammals Hall of the Smithsonian Institution.[18] In 1980 and 1984, scientists captured and tagged two male tigers in Chitwan National Park that weighed more than 270 kg (600 lb)
Bengal tigers are 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 they arrived in India approximately 12,000 years ago.[20] This recent history of tigers in the Indian subcontinent is consistent with the lack of tiger fossils from India 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.
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.[22] In 1929, the British taxonomist Pocock assumed that tigers arrived in southern India too late to colonize Ceylon, which earlier had been connected to India by a land bridge.[23]
In the Indian subcontinent, tigers inhabit tropical moist evergreen forests, tropical dry forests, tropical and subtropical moist deciduous forests, mangroves, subtropical and temperate upland forests, and alluvial grasslands. Latter tiger habitat once covered a huge swath of grassland and riverine and moist semi-deciduous forests along the major river system of the Gangetic and Brahmaputra plains, but has now been largely converted to agriculture or severely degraded. Today, the best examples of this habitat type are limitated to a few blocks at the base of the outer foothills of the Himalayas including the Tiger Conservation Units (TCUs) Rajaji-Corbett, Bardia-Banke, and the transboundary TCUs Chitwan-Parsa-Valmiki, Dudhwa-Kailali and Sukla Phanta-Kishanpur. Tiger densities in these blocks are high, in part a response to the extraordinary biomass of ungulate prey
India
In the past, Indian censuses of wild tigers relied on the individual identification of footprints known as pug marks — a method that has been criticized as deficient and inaccurate.[25]
Good tiger habitats in subtropical and temperate upland forests include the Tiger Conservation Units (TCUs) Manas-Namdapha. TCUs in tropical dry forest include Hazaribagh National Park, 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.[24]
The methodology used during the tiger census of 2008 extrapolates site-specific densities of tigers, their co-predators and prey derived from camera trap and sign surveys using GIS. Based on the result of these surveys, the total tiger population has been 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. The following six landscape complexes comprising several ecological landscapes were surveyed across India based on current tiger occupancy and potential for connectivity:[26]
in the Shivaliks–Gangetic flood plain landscape there are six populations with an estimated population size of 259 to 335 individuals occupying 5,080 square kilometres (1,960 sq mi) of forested habitats, which are located in Rajaji and Corbett national parks, in the connected habitats of Dudhwa National Park in Lakhimpur Kheri District, 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 occupying 48,610 square kilometres (18,770 sq mi) 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 occupying 7,772 square kilometres (3,001 sq mi) of 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, Baduel, Udayagiri and Giddalur;
in the Western Ghats landscape there are seven populations with an estimated population size of 336 to 487 individuals occupying 21,435 square kilometres (8,276 sq mi) forest in three major landscape units;
in the Brahmaputra flood plains and north-eastern hills tigers occupy 4,230 square kilometres (1,630 sq mi) in several patchy and fragmented forests;
in the Indian Sundarbans tigers occupy about 1,586 square kilometres (612 sq mi) of mangrove forest.
In May 2008, forest officials spotted 14 tiger cubs in Rajasthan's Ranthambore National Park.[27] In June 2008, a tiger from Ranthambore was relocated to Sariska Tiger Reserve, where all tigers had fallen victim to poachers and human encroachments since 2005.[28]
Nepal
The tiger population in the Terai of Nepal is split into three isolated subpopulations that are separated by cultivation and densely settled habitat. The largest population lives in Chitwan National Park and in the adjacent Parsa Wildlife Reserve encompassing an area of 2,543 km2 (982 sq mi) of prime lowland forest. To the west, the Chitwan population is isolated from the one in Bardia National Park and adjacent unprotected habitat further west, extending to within 15 km (9.3 mi) of the Sukla Phanta Wildlife Reserve, which harbours the smallest population.[29] The bottleneck between the Chitwan/Parsa and Bardia/Sukla Phanta metapopulations is situated just north of the town of Butwal.
As of 2009, an estimated 121 breeding tigers lived in Nepal.[30] By 2010, the number of adult tigers has reached 155.[4] A survey conducted from December 2009 to March 2010 indicates that 125 adult tigers live in Chitwan National Park and its border areas covering 1,261 km2 (487 sq mi).[31]
Bangladesh
As of 2004, population estimates in Bangladesh ranged from 200 to 419, mostly in the Sunderbans.[32][33] This region is the only mangrove habitat in this bioregion, where tigers survive, swimming between islands in the delta to hunt prey.[24] As of 2010, the mean estimated number is estimated at 440 adult tigers. Bangladesh's Forest Department is raising mangrove plantations supplying forage for spotted deer. Since 2001, afforestation has continued on a small scale in newly accreted lands and islands of the Sundarbans.[3]
Bhutan
As of 2005, the population in Bhutan is estimated at 67–81 individuals.[5] Tigers occur from an altitude of 200 m (660 ft) in the subtropical Himalayan foothills in the south along the border with India to over 3,000 m (9,800 ft) in the temperate forests in the north, and are known from 17 of 18 districts. Their stronghold appears to be the central belt of the country ranging in altitude between 2,000 and 3,500 m (6,600 and 11,500 ft), between the Mo River in the west and the Kulong River in the east.[34] In 2010, camera traps recorded a pair of tigers at altitudes of 3,000 to 4,100 m (9,800 to 13,500 ft). The male was recorded scent-marking, and the female can also be seen to be lactating, confirming that the pair are living within their own territory, and strongly suggesting they are breeding at that altitude.[35]
The basic social unit of the tiger is the elemental one of mother and offspring. Adult animals congregate only on an ad hoc and transitory basis when special conditions permit, such as plentiful supply of food. Otherwise they lead solitary lives, hunting individually for the dispersed forest and tall grassland animals, upon which they prey. They establish and maintain home ranges. Resident adults of either sex tend to confine their movements to a definite area of habitat within which they satisfy their needs, and in the case of tigresses, those of their growing cubs. Besides providing the requirements of an adequate food supply, sufficient water and shelter, and a modicum of peace and seclusion, this location must make it possible for the resident to maintain contact with other tigers, especially those of the opposite sex. Those sharing the same ground are well aware of each other’s movements and activities.[14]
In the Panna Tiger Reserve an adult radio-collared male tiger moved 1.7 to 10.5 km (1.1 to 6.5 mi) between locations on successive days in winter, and 1 to 13.9 km (0.62 to 8.6 mi) in summer. His home range was about 200 km2 (77 sq mi) in summer and 110 km2 (42 sq mi) in winter. Included in his home range were the much smaller home ranges of two females, a tigress with cubs and a sub-adult tigress. They occupied home ranges of 16 to 31 km2 (6.2 to 12 sq mi).[36]
The home ranges occupied by adult male residents tend to be mutually exclusive, even though one of these residents may tolerate a transient or sub-adult male at least for a time. 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. Spacing among females is less complete. Typically there is partial overlap with neighbouring female residents. They tend to have core areas, which are more exclusive, at least for most of the time. Home ranges of both males and females are not stable. The shift or alteration of a home range by one animal is correlated with a shift of another. Shifts from less suitable habitat to better ones are made by animals that are already resident. New animals become residents only as vacancies occur when a former resident moves out or dies. There are more places for resident females than for resident males.[14]
During seven years of camera trapping, tracking, and observational data in Chitwan National Park, 6 to 9 breeding tigers, 2 to 16 non-breeding tigers, and 6 to 20 young tigers of less than one year of age were detected in the study area of 100 km2 (39 sq mi). One of the resident females left her territory to one of her female offspring and took over an adjoining area by displacing another female; and a displaced female managed to re-establish herself in a neighboring territory made vacant by the death of the resident. Of 11 resident females, 7 were still alive at the end of the study period, 2 disappeared after losing their territories to rivals, and 2 died. The initial loss of two resident males and subsequent take over of their home ranges by new males caused social instability for two years. Of 4 resident males, 1 was still alive and 3 were displaced by rivals. Five litters of cubs were killed by infanticide, 2 litters died because they were too young to fend for themselves when their mothers died. One juvenile tiger was presumed dead after being photographed with severe injuries from a deer snare. The remaining young lived long enough to reach dispersal age, 2 of them becoming residents in the study area.
The Bengal tiger is the most numerous tiger subspecies with populations estimated at 1,520–1,909 in India, 440 in Bangladesh, 124–229 in Nepal and 67–81 in Bhutan.[2][3][4][5]
Bengal is traditionally fixed as the typical locality for the binomial Panthera tigris, to which the British taxonomist Reginald Innes Pocock subordinated the Bengal tiger in 1929 under the trinomial Panthera tigris tigris.[6]
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 is white, and the tail is white with black rings.
Male Bengal tigers had a total length, including the tail, from 270 to 310 cm (110 to 120 in), while females range from 240 to 265 cm (94 to 104 in).[8] Tails are 85 to 110 cm (33 to 43 in) long, and height at the shoulders is 90 to 110 cm (35 to 43 in).[9] The head and body length of three males captured in Nagarahole National Park ranged from 189 to 204 cm (74 to 80 in), with a tail length of 100 to 107 cm (39 to 42 in), while a single female measured 161 cm (63 in), with a tail length of 87 cm (34 in).[10] The average weight of males is 221.2 kg (488 lb), while that of females is 139.7 kg (308 lb).[11]
Males captured in Chitwan National Park in the early 1970s had an average weight of 235 kg (520 lb) ranging from 200 to 261 kg (440 to 580 lb), and that of the females was 140 kg (310 lb) ranging from 116 to 164 kg (260 to 360 lb).[12] Males from the northern India are as large as Siberian tigers with a greatest length of skull of 332 to 376 mm (13.1 to 14.8 in).[13]
The white tiger is a recessive mutant of the Bengal tiger, which was reported in the wild from time to time in Assam, Bengal, Bihar and especially from the former State of Rewa. 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.
Two tigers shot in Kumaon and near Oude at the end of the 19th century allegedly measured more than 12 ft (370 cm). But at the time, sportsmen had not yet adopted a correct system of measurement, some measuring between pegs and others round the curves.[15]
In the beginning of the 20th century, a male Bengal tiger was shot in central India with a head and body length of 221 cm (87 in) measured between pegs, 150 cm (59 in) of chest girth, a shoulder height of 109 cm (43 in) and a tail of just 81 cm (32 in), 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).[16]
A heavy male weighing 570 lb (260 kg) was shot in northern India in the 1930s.[17] The heaviest known tiger was a huge male killed in 1967 that weighed 388.7 kg (857 lb) and measured 322 cm (127 in) in total length between the pegs, and 338 cm (133 in) over curves. This specimen is on exhibition in the Mammals Hall of the Smithsonian Institution.[18] In 1980 and 1984, scientists captured and tagged two male tigers in Chitwan National Park that weighed more than 270 kg (600 lb)
Bengal tigers are 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 they arrived in India approximately 12,000 years ago.[20] This recent history of tigers in the Indian subcontinent is consistent with the lack of tiger fossils from India 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.
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.[22] In 1929, the British taxonomist Pocock assumed that tigers arrived in southern India too late to colonize Ceylon, which earlier had been connected to India by a land bridge.[23]
In the Indian subcontinent, tigers inhabit tropical moist evergreen forests, tropical dry forests, tropical and subtropical moist deciduous forests, mangroves, subtropical and temperate upland forests, and alluvial grasslands. Latter tiger habitat once covered a huge swath of grassland and riverine and moist semi-deciduous forests along the major river system of the Gangetic and Brahmaputra plains, but has now been largely converted to agriculture or severely degraded. Today, the best examples of this habitat type are limitated to a few blocks at the base of the outer foothills of the Himalayas including the Tiger Conservation Units (TCUs) Rajaji-Corbett, Bardia-Banke, and the transboundary TCUs Chitwan-Parsa-Valmiki, Dudhwa-Kailali and Sukla Phanta-Kishanpur. Tiger densities in these blocks are high, in part a response to the extraordinary biomass of ungulate prey
India
In the past, Indian censuses of wild tigers relied on the individual identification of footprints known as pug marks — a method that has been criticized as deficient and inaccurate.[25]
Good tiger habitats in subtropical and temperate upland forests include the Tiger Conservation Units (TCUs) Manas-Namdapha. TCUs in tropical dry forest include Hazaribagh National Park, 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.[24]
The methodology used during the tiger census of 2008 extrapolates site-specific densities of tigers, their co-predators and prey derived from camera trap and sign surveys using GIS. Based on the result of these surveys, the total tiger population has been 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. The following six landscape complexes comprising several ecological landscapes were surveyed across India based on current tiger occupancy and potential for connectivity:[26]
in the Shivaliks–Gangetic flood plain landscape there are six populations with an estimated population size of 259 to 335 individuals occupying 5,080 square kilometres (1,960 sq mi) of forested habitats, which are located in Rajaji and Corbett national parks, in the connected habitats of Dudhwa National Park in Lakhimpur Kheri District, 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 occupying 48,610 square kilometres (18,770 sq mi) 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 occupying 7,772 square kilometres (3,001 sq mi) of 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, Baduel, Udayagiri and Giddalur;
in the Western Ghats landscape there are seven populations with an estimated population size of 336 to 487 individuals occupying 21,435 square kilometres (8,276 sq mi) forest in three major landscape units;
in the Brahmaputra flood plains and north-eastern hills tigers occupy 4,230 square kilometres (1,630 sq mi) in several patchy and fragmented forests;
in the Indian Sundarbans tigers occupy about 1,586 square kilometres (612 sq mi) of mangrove forest.
In May 2008, forest officials spotted 14 tiger cubs in Rajasthan's Ranthambore National Park.[27] In June 2008, a tiger from Ranthambore was relocated to Sariska Tiger Reserve, where all tigers had fallen victim to poachers and human encroachments since 2005.[28]
Nepal
The tiger population in the Terai of Nepal is split into three isolated subpopulations that are separated by cultivation and densely settled habitat. The largest population lives in Chitwan National Park and in the adjacent Parsa Wildlife Reserve encompassing an area of 2,543 km2 (982 sq mi) of prime lowland forest. To the west, the Chitwan population is isolated from the one in Bardia National Park and adjacent unprotected habitat further west, extending to within 15 km (9.3 mi) of the Sukla Phanta Wildlife Reserve, which harbours the smallest population.[29] The bottleneck between the Chitwan/Parsa and Bardia/Sukla Phanta metapopulations is situated just north of the town of Butwal.
As of 2009, an estimated 121 breeding tigers lived in Nepal.[30] By 2010, the number of adult tigers has reached 155.[4] A survey conducted from December 2009 to March 2010 indicates that 125 adult tigers live in Chitwan National Park and its border areas covering 1,261 km2 (487 sq mi).[31]
Bangladesh
As of 2004, population estimates in Bangladesh ranged from 200 to 419, mostly in the Sunderbans.[32][33] This region is the only mangrove habitat in this bioregion, where tigers survive, swimming between islands in the delta to hunt prey.[24] As of 2010, the mean estimated number is estimated at 440 adult tigers. Bangladesh's Forest Department is raising mangrove plantations supplying forage for spotted deer. Since 2001, afforestation has continued on a small scale in newly accreted lands and islands of the Sundarbans.[3]
Bhutan
As of 2005, the population in Bhutan is estimated at 67–81 individuals.[5] Tigers occur from an altitude of 200 m (660 ft) in the subtropical Himalayan foothills in the south along the border with India to over 3,000 m (9,800 ft) in the temperate forests in the north, and are known from 17 of 18 districts. Their stronghold appears to be the central belt of the country ranging in altitude between 2,000 and 3,500 m (6,600 and 11,500 ft), between the Mo River in the west and the Kulong River in the east.[34] In 2010, camera traps recorded a pair of tigers at altitudes of 3,000 to 4,100 m (9,800 to 13,500 ft). The male was recorded scent-marking, and the female can also be seen to be lactating, confirming that the pair are living within their own territory, and strongly suggesting they are breeding at that altitude.[35]
The basic social unit of the tiger is the elemental one of mother and offspring. Adult animals congregate only on an ad hoc and transitory basis when special conditions permit, such as plentiful supply of food. Otherwise they lead solitary lives, hunting individually for the dispersed forest and tall grassland animals, upon which they prey. They establish and maintain home ranges. Resident adults of either sex tend to confine their movements to a definite area of habitat within which they satisfy their needs, and in the case of tigresses, those of their growing cubs. Besides providing the requirements of an adequate food supply, sufficient water and shelter, and a modicum of peace and seclusion, this location must make it possible for the resident to maintain contact with other tigers, especially those of the opposite sex. Those sharing the same ground are well aware of each other’s movements and activities.[14]
In the Panna Tiger Reserve an adult radio-collared male tiger moved 1.7 to 10.5 km (1.1 to 6.5 mi) between locations on successive days in winter, and 1 to 13.9 km (0.62 to 8.6 mi) in summer. His home range was about 200 km2 (77 sq mi) in summer and 110 km2 (42 sq mi) in winter. Included in his home range were the much smaller home ranges of two females, a tigress with cubs and a sub-adult tigress. They occupied home ranges of 16 to 31 km2 (6.2 to 12 sq mi).[36]
The home ranges occupied by adult male residents tend to be mutually exclusive, even though one of these residents may tolerate a transient or sub-adult male at least for a time. 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. Spacing among females is less complete. Typically there is partial overlap with neighbouring female residents. They tend to have core areas, which are more exclusive, at least for most of the time. Home ranges of both males and females are not stable. The shift or alteration of a home range by one animal is correlated with a shift of another. Shifts from less suitable habitat to better ones are made by animals that are already resident. New animals become residents only as vacancies occur when a former resident moves out or dies. There are more places for resident females than for resident males.[14]
During seven years of camera trapping, tracking, and observational data in Chitwan National Park, 6 to 9 breeding tigers, 2 to 16 non-breeding tigers, and 6 to 20 young tigers of less than one year of age were detected in the study area of 100 km2 (39 sq mi). One of the resident females left her territory to one of her female offspring and took over an adjoining area by displacing another female; and a displaced female managed to re-establish herself in a neighboring territory made vacant by the death of the resident. Of 11 resident females, 7 were still alive at the end of the study period, 2 disappeared after losing their territories to rivals, and 2 died. The initial loss of two resident males and subsequent take over of their home ranges by new males caused social instability for two years. Of 4 resident males, 1 was still alive and 3 were displaced by rivals. Five litters of cubs were killed by infanticide, 2 litters died because they were too young to fend for themselves when their mothers died. One juvenile tiger was presumed dead after being photographed with severe injuries from a deer snare. The remaining young lived long enough to reach dispersal age, 2 of them becoming residents in the study area.
The Royal Bengal Tiger
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