Tiger (Panthera tigris)
Taxonomy and etymology
In 1758, Linnaeus first described the species in his work Systema Naturae under the scientific name Felis tigris. In 1929, the British taxonomist Reginald Innes Pocock subordinated the species under the genus Panthera using the scientific name Panthera tigris.
The word Panthera is probably of Oriental origin and retraceable to the Ancient Greek word panther, the Latin word panthera, the Old French word pantere, most likely meaning "the yellowish animal", or from pandarah meaning whitish-yellow. The derivation from Greek pan- ("all") and ther ("beast") may be folk etymology that led to many curious fables.
The word "tiger" is retraceable to the Latin word tigris meaning a spotted tiger hound of Actaeon. The Greek word tigris is possibly derived from a Persian source.
The Tiger once ranged widely across Asia, from Turkey in
the west to the eastern coast of Russia (Nowell and Jackson 1996). Over the past
100 years Tigers have disappeared from Southwest and Central Asia, from two
Indonesian islands (Java and Bali) and from large areas of Southeast and Eastern
Asia. Tigers have lost over 93% of their historic range (Sanderson et al. 2006,
Walston et al. 2010b). Tigers are currently found in thirteen Asian range
states: Bangladesh, Bhutan, Cambodia, China, India, Indonesia, Lao PDR,
Malaysia, Myanmar, Nepal, Russia, Thailand and Vietnam. They may still
persist in North Korea, although there has been no recent confirmed evidence.
In 1994, the first comprehensive assessment to delineate Tiger range was carried out (Dinerstein et al. 1997). Priority areas for Tiger conservation were estimated to total 1.64 million km² in 159 Tiger Conservation Units (TCUs), roughly equivalent to discrete meta-populations, not including Russia (later estimated at 270,0000 km²: Sanderson et al. 2006) and China. While this was generally considered representative of current distribution, Tiger presence was confirmed in just 47% the TCUs, and 89% were scored as undergoing medium to high levels of poaching of Tigers and their prey.
This exercise was revised and updated ten years later, and in delineating Tiger Conservation Landscapes (TCLs), greater emphasis was placed on actual records of Tiger presence and breeding (Sanderson et al. 2006). TCLs were defined as areas where there is sufficient habitat to conserve at least five Tigers, and Tigers have been confirmed to occur in the past decade. Tiger range was estimated at 1.1 million km² in 76 TCLs (again, roughly equivalent to discrete meta-populations). This represented a 41% decline from the range described a decade earlier (in South and Southeast Asia, a drop from 1.55 million km² to 914,000 km²: Sanderson et al. 2006: 63), attributed primarily to poaching pressure (Dinerstein et al. 2007). Habitat loss due to deforestation was also to blame, notable particularly in Sumatra and Myanmar (Wikramanayake et al. 2010). In India, landscapes with Tigers found to be much smaller and more fragmented than in the original assessment (Sanderson et al. 2006: 63 and Figure 4.12).
Records of Tigers were collected over a ten-year period (1995–2004), a period which may have been too liberal for places like Cambodia which underwent a sharp rise in poaching pressure in the 1990s (Sanderson et al. 2006: Appendix 6). While 53% of the TCU survey respondents reported evidence of Tiger breeding in the time period 1995–2004, out of over 2,500 point records collected in 2005, just 8% had confirmed evidence of breeding Tigers (Sanderson et al. 2006: 11-17). Large areas of habitat were defined as Tiger landscapes based on suitability, but given data paucity on Tiger presence there were often few records of breeding and actual Tiger occupancy to substantiate these (Sanderson et al. 2006: Figures 2.3 and 4.8).
A review of land management within Tiger Conservation Landscapes described the TCLs as “potential habitat for Tigers” and found only 21% of their area to be legally protected. Management effectiveness was generally poor in the protected areas, with regulatory, budgetary and enforcement constraints, and hunting cited as the main threat. Significant portions of the TCLs are designated concessions for resource extraction (timber, oil and gas, minerals, etc.) (Forrest et al. 2011).
Tiger range was revisited again in 2009, by which time the extent of the Tiger’s range collapse had become evident. “Vast areas of Southeast Asia [were] recently found to be void of Tigers and depleted of prey by hunters” (Walston et al. 2010a: 5). The exercise used a different methodology to prioritize areas for Tiger conservation. Source Sites were defined as areas with confirmed current presence of Tigers and evidence of breeding, population estimates of >25 breeding females, legal protection, and embedded in a larger habitat landscape with the potential to hold >50 breeding females. An extensive review of scientific literature as well as correspondence with Tiger scientists and protected area managers resulted in the identification of just 42 source sites totalling approximately 90,000 km². Many Southeast Asian countries, previously considered to have large areas with Tigers, are now considered, on the basis of extensive survey effort over the past decade or more, to have essentially no healthy breeding populations: Myanmar, Cambodia, Vietnam and Bhutan have no confirmed source sites (although some sites with potential), and Laos just one (Walston et al. 2010a,b).
On the range map accompanying this Red List assessment, the Source Sites are delineated as Extant range, and the Tiger Conservation Landscapes as Probably Extant, as they are based primarily on “realistic inferences (e.g., based on distribution of suitable habitat at appropriate altitudes and proximity to areas where the taxon is known or thought very likely to remain extant,” as defined by the IUCN Red List of Threatened Species).
Bangladesh; Bhutan; Cambodia; China (Anhui - Regionally Extinct, Beijing - Regionally Extinct, Chongqing - Regionally Extinct, Fujian - Possibly Extinct, Guangdong - Possibly Extinct, Guangxi - Regionally Extinct, Guizhou - Regionally Extinct, Hebei - Regionally Extinct, Heilongjiang, Henan - Regionally Extinct, Hubei - Regionally Extinct, Hunan - Possibly Extinct, Jiangsu - Regionally Extinct, Jiangxi - Possibly Extinct, Jilin, Liaoning - Regionally Extinct, Shaanxi - Possibly Extinct, Shandong - Regionally Extinct, Shanghai - Regionally Extinct, Shanxi - Regionally Extinct, Sichuan - Regionally Extinct, Tianjin - Regionally Extinct, Tibet [or Xizang], Xinjiang - Regionally Extinct, Yunnan, Zhejiang - Possibly Extinct); India; Indonesia (Bali - Regionally Extinct, Jawa - Regionally Extinct, Sumatera); Lao People's Democratic Republic; Malaysia (Peninsular Malaysia); Myanmar; Nepal; Russian Federation; Thailand; Vietnam
Korea, Democratic People's Republic of
Afghanistan; Iran, Islamic Republic of; Kazakhstan; Kyrgyzstan; Pakistan; Singapore; Tajikistan; Turkey; Turkmenistan; Uzbekistan
Tigers have muscular bodies with particularly powerful
forelimbs and large heads. The pelage coloration varies between shades of orange
or brown with white ventral areas and distinctive black stripes. The face has
long whiskers, which are especially long in males. The pupils are circular with
yellow irises. The small, rounded ears have black markings on the back,
surrounding a white spot. These spots, called ocelli, play an important role in
The pattern of stripes is unique to each animal, these unique markings can be used by researchers to identify individuals (both in the wild and captivity), much in the same way that fingerprints are used to identify humans. It seems likely that the function of stripes is camouflage, serving to help tigers conceal themselves amongst the dappled shadows and long grass of their environment as they stalk their prey. The stripe pattern is also found on the skin of the tiger. If a tiger were to be shaved, its distinctive camouflage pattern would be preserved.
The tiger are the most variable in size of all big cats, even more so than the leopard and much more so than lions. The Bengal, Caspian and Siberian tiger subspecies represent the largest living felids, and rank among the biggest felids that ever existed. An average adult male tiger from Northern India or Siberia outweighs an average adult male lion by around 45.5 kg (100 lb). Females vary in length from 200 to 275 cm (79 to 108 in), weigh 65 to 167 kg (140 to 370 lb) with a greatest length of skull ranging from 268 to 318 mm (10.6 to 12.5 in). Males vary in size from 250 to 390 cm (98 to 150 in), weigh 90 to 306 kg (200 to 670 lb) with a greatest length of skull ranging from 316 to 383 mm (12.4 to 15.1 in). Body size of different populations seems to be correlated with climate—Bergmann's Rule—and can be explained from the point of view of thermoregulation. Large male Siberian tigers can reach a total length of more than 3.5 m (11.5 ft) "over curves", 3.3 m (10.8 ft) "between pegs" and a weight of 306 kg (670 lb). This is considerably larger than the size reached by the smallest living tiger subspecies, the Sumatran tiger, which reach a body weight of 75 to 140 kg (170 to 310 lb). Of the total length of a tiger, the tail comprises 0.6 to 1.1 m (2.0 to 3.6 ft).At the shoulder, tigers may variously stand 0.7 to 1.22 m (2.3 to 4.0 ft) tall. The accepted record weight, per the Guinness Book of World Records, for a wild tiger was 389 kg (860 lb) for a Bengal tiger shot in 1967, though its weight may have been boosted by the fact that it had eaten a water buffalo the previous night. Tigresses are smaller than the males in each subspecies, although the size difference between male and female tigers tends to be more pronounced in the larger tiger subspecies, with males weighing up to 1.7 times more than the females. In addition, male tigers have wider forepaw pads than females. Biologists use this difference to determine gender based on tiger tracks. The skull of the tiger is very similar to that of the lion, though the frontal region is usually not as depressed or flattened, with a slightly longer postorbital region. The skull of a lion has broader nasal openings. However, due to the amount of skull variation in the two species, usually, only the structure of the lower jaw can be used as a reliable indicator of species.
There are nine subspecies of tiger, three of which are extinct. Their historical range in Bangladesh, Siberia, Iran, Afghanistan, India, China, and southeast Asia, including three Indonesian islands is severely diminished today. The surviving subspecies, in descending order of wild population, are:
The Bengal tiger (Panthera tigris tigris), also called the Indian tiger, lives in India, Nepal, Bhutan and Bangladesh, and is the most common subspecies with populations estimated at less than 2,500 adult individuals. In 2011 the total population of adult tigers is estimated at 1,520–1,909 in India, 440 in Bangladesh, 155 in Nepal and 75 in Bhutan. It lives in alluvial grasslands, subtropical and tropical rainforests, scrub forests, wet and dry deciduous forests, and mangroves. Male Bengal tigers had a total length, including the tail, of 270 to 310 cm (110 to 120 in), while females range from 240 to 265 cm (94 to 104 in). The weight of males range from 175 to 260 kg (390 to 570 lb), while that of the females range from 100 to 181 kg (220 to 400 lb).In northern India and Nepal, tigers tend to be of larger size. Males often average 235 kilograms (520 lb), while females average 141 kilograms (310 lb). In 1972, Project Tiger was founded in India aiming at ensuring a viable population of tigers in the country and preserving areas of biological importance as a natural heritage for the people. But the illicit demand for bones and body parts from wild tigers for use in Traditional Chinese medicine is the reason for the unrelenting poaching pressure on tigers on the Indian subcontinent. Between 1994 and 2009, the Wildlife Protection Society of India has documented 893 cases of tigers killed in India, which is just a fraction of the actual poaching and illegal trade in tiger parts during those years. An area of special conservation interest lies in the Terai Arc Landscape in the Himalayan foothills of northern India and southern Nepal, where 11 protected areas comprising dry forest foothills and tall grass savannas harbour tigers in a 49,000 square kilometres (19,000 sq mi) landscape. 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. The approach has been successful in reducing poaching, restoring habitats, and creating a local constituency for conservation.
The Indochinese tiger (Panthera tigris corbetti), also called Corbett's tiger, is found in Cambodia, China, Laos, Burma, Thailand, and Vietnam. These tigers are smaller and darker than Bengal tigers: Males weigh from 150–190 kg (330–420 lb) while females are smaller at 110–140 kg (240–310 lb). Their preferred habitat is forests in mountainous or hilly regions. According to government estimates of national tiger populations, the subspecies numbers around a total of 350 individuals. All existing populations are at extreme risk from poaching, prey depletion as a result of poaching of primary prey species such as deer and wild pigs, habitat fragmentation and inbreeding. In Vietnam, almost three-quarters of the tigers killed provide stock for Chinese pharmacies.
The Malayan tiger (Panthera tigris jacksoni), exclusively found in the southern part of the Malay Peninsula, was not considered a subspecies in its own right until 2004. The new classification came about after a study by Luo et al. from the Laboratory of Genomic Diversity Study, part of the National Cancer Institute of the United States. According to official government figures, the population in the wild may number around 500 individuals, but is under considerable poaching pressure. The Malayan tiger is the smallest of the mainland tiger subspecies, and the second smallest living subspecies, with males averaging about 120 kg (260 lb) and females about 100 kg (220 lb) in weight. The Malayan tiger is a national icon in Malaysia, appearing on its coat of arms and in logos of Malaysian institutions, such as Maybank.
The Sumatran tiger (Panthera tigris sumatrae) is found only on the Indonesian island of Sumatra, and is critically endangered. It is the smallest of all living tiger subspecies, with adult males weighing between 100–140 kg (220–310 lb) and females 75–110 kg (170–240 lb). Their small size is an adaptation to the thick, dense forests of the island of Sumatra where they reside, as well as the smaller-sized prey. The wild population is estimated at between 400 and 500, seen chiefly in the island's national parks. Recent genetic testing has revealed the presence of unique genetic markers, indicating that it may develop into a separate species, if it does not go extinct. This has led to suggestions that Sumatran tigers should have greater priority for conservation than any other subspecies. While habitat destruction is the main threat to existing tiger population (logging continues even in the supposedly protected national parks), 66 tigers were recorded as being shot and killed between 1998 and 2000, or nearly 20% of the total population.
The Siberian tiger (Panthera tigris altaica), also known as the Amur tiger, inhabits the Amur-Ussuri region of Primorsky Krai and Khabarovsk Krai in far eastern Siberia. It ranks among the biggest felids that have ever existed with a head and body length of 160–180 cm (63–71 in) for females and 190–230 cm (75–91 in) for males, plus a tail of about 60–110 cm (24–43 in) and an average weight of around 227 kg (500 lb) for males. Siberian tigers have thick coats and a paler golden hue and fewer stripes. The heaviest wild Siberian tiger weighed 384 kg (850 lb) but according to Mazák this record is not reliable. In 2005, there were 331–393 adult-subadult Siberian tigers in the region, with a breeding adult population of about 250 individuals. The population has been stable for more than a decade, but partial surveys conducted after 2005 indicate that the Russian tiger population is declining. At the turn of the century, the phylogenetic relationships of tiger subspecies was re-assessed, and a remarkable similarity between the Siberian and Caspian tiger observed indicating that the Siberian tiger population is the genetically closest living relative of the extinct Caspian tiger, and strongly implying a very recent common ancestry for the two groups.
The South China tiger (Panthera tigris amoyensis), also known as the Amoy or Xiamen tiger, is the most critically endangered subspecies of tiger and is listed as one of the 10 most endangered animals in the world. One of the smaller tiger subspecies, the length of the South China tiger ranges from 2.2–2.6 m (87–100 in) for both males and females. Males weigh between 127 and 177 kg (280 and 390 lb) while females weigh between 100 and 118 kg (220 and 260 lb). From 1983 to 2007, no South China tigers were sighted. In 2007 a farmer spotted a tiger and handed in photographs to the authorities as proof. The photographs in question, however, were later exposed as fake, copied from a Chinese calendar and digitally altered, and the "sighting" turned into a massive scandal. In 1977, the Chinese government passed a law banning the killing of wild tigers, but this may have been too late to save the subspecies, since it is possibly already extinct in the wild. There are currently 59 known captive South China tigers, all within China, but these are known to be descended from only six animals. Thus, the genetic diversity required to maintain the subspecies may no longer exist. Currently, there are breeding efforts to reintroduce these tigers to the wild.
Hybridisation among the big cats, including the tiger, was first conceptualised in the 19th century, when zoos were particularly interested in the pursuit of finding oddities to display for financial gain. Lions have been known to breed with tigers (most often the Amur and Bengal subspecies) to create hybrids called ligers and tigons. Such hybrids were once commonly bred in zoos, but this is now discouraged due to the emphasis on conserving species and subspecies. Hybrids are still bred in private menageries and in zoos in China.
The liger is a cross between a male lion and a tigress. Because the lion sire passes on a growth-promoting gene, but the corresponding growth-inhibiting gene from the female tiger is absent, ligers grow far larger than either parent. They share physical and behavioural qualities of both parent species (spots and stripes on a sandy background). Male ligers are sterile, but female ligers are often fertile. Males have about a 50% chance of having a mane, but, even if they do, their manes will be only around half the size of that of a pure lion. Ligers are typically between 10 to 12 feet in length, and can be between 800 and 1,000 pounds or more.
The less common tigons is a cross between the lioness and the male tiger.
There is a well-known allele that produces the white tiger, technically known as chinchilla Calvinistic, an animal which is rare in the wild, but widely bred in zoos due to its popularity. Breeding of white tigers will often lead to inbreeding (as the trait is recessive). Many initiatives have taken place in white and orange tiger mating in an attempt to remedy the issue, often mixing subspecies in the process. Such inbreeding has led to white tigers having a greater likelihood of being born with physical defects, such as cleft palates and scoliosis (curvature of the spine). Furthermore, white tigers are prone to having crossed eyes (a condition known as strabismus). Even apparently healthy white tigers generally do not live as long as their orange counterparts. Recordings of white tigers were first made in the early 19th century. They can only occur when both parents carry the rare gene found in white tigers; this gene has been calculated to occur in only one in every 10,000 births. The white tiger is not a separate sub-species, but only a colour variation; since the only white tigers that have been observed in the wild have been Bengal tigers (and all white tigers in captivity are at least part Bengal), it is commonly thought that the recessive gene that causes the white colouring is probably carried only by Bengal tigers, although the reasons for this are not known. Nor are they in any way more endangered than tigers are generally, this being a common misconception. Another misconception is that white tigers are albinos, despite the fact that pigment is evident in the white tiger's stripes. They are distinct not only because of their white hue; they also have blue eyes.
In addition, another recessive gene may create a very unusual "golden" or "golden tabby" colour variation, sometimes known as "strawberry." Golden tigers have light gold fur, pale legs and faint orange stripes. Their fur tends to be much thicker than normal. There are extremely few golden tigers in captivity, around 30 in all. Like white tigers, golden tigers are invariably at least part Bengal. Some golden tigers carry the white tiger gene, and when two such tigers are mated, can produce some stripe less white offspring. Both white and golden tigers tend to be larger than average Bengal tigers.
Other colour variations
There is no authenticated case of a black tiger, with the possible exception of one dead specimen examined in Chittagong in 1846.There are unconfirmed reports of a "blue" or slate-coloured tiger, the Maltese tiger. Largely or totally black tigers are assumed, if real, to be intermittent mutations rather than distinct species.
The thirteen Tiger Range Countries have come together in an
unprecedented pledge to double the world’s Tiger population by 2022, the next
Year of the Tiger on the Asian lunar calendar, with a goal of achieving at least
6,000 Tigers. This figure was based on a baseline global population of 3,200,
agreed upon at a preparatory workshop held in Kathmandu, Nepal in October 2009;
3,200 Tigers was the IUCN Red List population estimate at that time. Since then,
Tiger Range Countries have adjusted their baseline national Tiger estimates,
finalized in the Global Tiger Recovery Program adopted at the International
Tiger Forum in St Petersburg, Russia in November 2010 (GTRP 2010). These
estimates now total approximately 4,000 adult Tigers (see Table, which updates
the GTRP’s figure for India based on its most recent national census results
[Jhala et al. 2011]).
However, estimates of the Tiger populations in 42 protected source sites where there is evidence of breeding total 2,154 Tigers (Walston et al. 2010a, modified from their 2,126 to include the most recent published estimates from Nepal of Tiger populations in Chitwan, Bardia and Shuklaphanta). Although this is not a complete estimate of the global Tiger population (for example, most Amur Tigers in Russia are found in unprotected areas), generally Tiger status outside the source sites is poor and poorly known. IUCN Guidelines (IUCN Standards and Petitions Subcommittee 2010) define population as the number of mature individuals, defined as “individuals known, estimated or inferred to be capable of reproduction.” While in general this refers to all reproductive-age adults in the population, the Guidelines also “stress that the intention of the definition of mature individuals is to allow the estimate of the number of mature individuals to take account of all the factors that may make a taxon more vulnerable than otherwise might be expected.” Tigers require large populations to persist, and the survival rate of breeding adult females is a key parameter, with models suggesting population declines when mortality of breeding females rises over 15% (Chapron et al. 2008). Population declines in recent years have been most pronounced outside protected areas (Walston et al. 2010b). The IUCN Guidelines advise that “mature individuals that will never produce new recruits should not be counted.” For the purposes of Red List assessment, the estimated population in the Source Sites is used as a proxy for the breeding population of adult Tigers.
In 1998, the global Tiger population was estimated, less rigorously, at 5,000 to 7,000 Tigers (Seidensticker et al. 1999). Although to some extent the new numbers represent improved knowledge, it is clear that there have been substantial population declines, with Tigers all but eliminated from much of their recent forest range, particularly in Southeast Asia.
Habitat and Ecology:
Tigers are found mainly in the forests of tropical Asia, although they historically occurred more widely in drier and colder climes. One subspecies, the Amur Tiger P.t. altaica, persists in the Russian Far East. Photos of Tigers up to 4,500 m have been obtained in Bhutan (Wang 2008). Availability of a sufficient prey base of large ungulates is the Tiger's major habitat requirement: "wild pigs and deer of various species are the two prey types that make up the bulk of the Tiger's diet, and in general Tigers require a good population of these species in order to survive and reproduce" (Sunquist and Sunquist 2002). Based on studies, Karanth et al. (2004) estimate that Tigers need to kill 50 large prey animals per year. Tigers are opportunistic predators, however, and their diet includes birds, fish, rodents, insects, amphibians, reptiles in addition to other mammals such as primates and porcupines. Tigers can also take ungulate prey much larger than themselves, including large bovids (water buffalo, gaur, banteng), elephants and rhinos (Nowell and Jackson 1996). Tigers are generally solitary, with adults maintaining exclusive territories, or home ranges. Adult female home ranges seldom overlap, whereas male ranges typically overlap from 1–3 females, a typical felid pattern of social organization. Tiger home ranges are small where prey is abundant - e.g., female home ranges in Chitwan averaged 20 km², while in the Russian Far East they are much larger at 450 km² (Sunquist and Sunquist 2002). Similarly, reported Tiger densities range from 11.65 adult Tigers per 100 km² where prey is abundant (India's Nagarhole National Park) to as low as 0.13–0.45 per 100 km² where prey is more thinly distributed, as in Russia's Sikhote Alin Mountains (Nowell and Jackson 1996).
In the past, tigers were found throughout Asia, from the
Caucasus and the Caspian Sea to Siberia and the Indonesian islands of Java, Bali
and Sumatra. During the 20th century, tigers have been extirpated in western
Asia and became restricted to isolated pockets in the remaining parts of their
range. Today, their fragmented and partly degraded range extends from India in
the west to China and Southeast Asia. The northern limit of their range is close
to the Amur River in south eastern Siberia. The only large island inhabited by
tigers today is Sumatra.
Tigers were extirpated on the island of Bali in the 1940s, around the Caspian Sea in the 1970s, and on Java in the 1980s. Loss of habitat and the persistent killing of tigers and tiger prey precipitated these extirpations, a process that continues to leave forests devoid of tigers and other large mammals across South and Southeast Asia. Since the beginning of the 21st century, their historical range has shrunk by 93%. In the decade from 1997 to 2007, the estimated area known to be occupied by tigers has declined by 41%.
Fossil remains indicate that tigers were present in Borneo and Palawan in the Philippines during the late Pleistocene and Holocene.
Tigers can occupy a wide range of habitat types but will usually require sufficient cover, proximity to water, and an abundance of prey. Bengal tigers live in many types of forests, including wet, evergreen, the semi-evergreen of Assam and eastern Bengal; the swampy mangrove forest of the Ganges Delta; the deciduous forest of Nepal, and the thorn forests of the Western Ghats. In various parts of their range they inhabit or have inhabited additionally partially open grassland and savanna as well as taiga forests and rocky habitats. Compared to the lion, the tiger prefers denser vegetation, for which its camouflage colouring is ideally suited, and where a single predator is not at a disadvantage compared with the multiple felines in a pride. A further habitat requirement is the placement of suitably secluded den locations, which may consist of caves, large hollow trees or dense vegetation.
Adult tigers lead solitary lives and congregate only on an ad hoc and transitory basis when special conditions permit, such as plentiful supply of food. 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. Those sharing the same ground are well aware of each other's movements and activities. The size of a tiger's home range mainly depends on prey abundance, and, in the case of male tigers, on access to females. A tigress may have a territory of 20 km2 (7.7 sq mi), while the territories of males are much larger, covering 60 to 100 km2 (23 to 39 sq mi). The range of a male tends to overlap those of several females.
Tigers are strong swimmers, and are often found bathing in ponds, lakes, and rivers. Among fellow big cats, only the jaguar shares with the tiger a similar fondness for and capability in the water. They may also cross rivers up to 6 to 7 km (3.7 to 4.3 mi) across and can swim a distance of up to 29 km (18 mi) in a day. During the extreme heat of the day, they often cool off in pools. They are able to carry prey through or capturing it in the water. The relationships between individuals can be quite complex, and it appears that there is no set "rule" that tigers follow with regards to territorial rights and infringing territories. For instance, although for the most part tigers avoid each other, both male and female tigers have been documented sharing kills, usually with others of the opposite sex or cub. George Schaller observed a male tiger share a kill with two females and four cubs. Females are often reluctant to let males near their cubs, but Schaller saw that these females made no effort to protect or keep their cubs from the male, suggesting that the male might have been the father of the cubs. In contrast to male lions, male tigers will allow the females and cubs to feed on the kill first. Furthermore, tigers seem to behave relatively amicably when sharing kills, in contrast to lions, which tend to squabble and fight. Unrelated tigers have also been observed feeding on prey together. The following quotation is from Stephen Mills' book Tiger, as he describes an event witnessed by Valmiki Thapar and Fateh Singh Rathore in Ranthambhore National Park: A dominant tigress they called Padmini killed a 250 kg (550 lb) male nilgai – a very large antelope. They found her at the kill just after dawn with her three 14-month-old cubs and they watched uninterrupted for the next ten hours. During this period the family was joined by two adult females and one adult male – all offspring from Padmini's previous litters and by two unrelated tigers, one female the other unidentified. By three o'clock there were no fewer than nine tigers round the kill.
When young female tigers first establish a territory, they tend to do so fairly close to their mother's area. The overlap between the female and her mother's territory tends to wane with increasing time. Males, however, wander further than their female counterparts, and set out at a younger age to mark out their own area. A young male will acquire territory either by seeking out a range devoid of other male tigers, or by living as a transient in another male's territory until he is old and strong enough to challenge the resident male. The highest mortality rate (30–35% per year) amongst adult tigers occurs for young male tigers who have just left their natal area, seeking out territories of their own.
Male tigers are generally more intolerant of other males within their territory than females are of other females. For the most part, however, territorial disputes are usually solved by displays of intimidation, rather than outright aggression. Several such incidents have been observed, in which the subordinate tiger yielded defeat by rolling onto its back, showing its belly in a submissive posture. Once dominance has been established, a male may actually tolerate a subordinate within his range, as long as they do not live in too close quarters. The most violent disputes tend to occur between two males when a female is in oestrus, and may result in the death of one of the males, although this is a rare occurrence. To identify his territory, the male marks trees by spraying of urine and anal gland secretions, as well as marking trails with scat. Males show a grimacing face, called the Flehmen response, when identifying a female's reproductive condition by sniffing their urine markings. Like the other Panthera cats, tigers can roar. Tigers will roar for both aggressive and non-aggressive reasons. Other tiger vocal communications include moans, hisses, growls and chuffs.
Tigers have been studied in the wild using a variety of techniques. The populations of tigers were estimated in the past using plaster casts of their pugmarks. This method was criticized as being inaccurate. Attempts were made to use camera trapping instead. Newer techniques based on DNA from their scat are also being evaluated. Radio collaring has also been a popular approach to tracking them for study in the wild.
Hunting and diet
In the wild, tigers mostly feed on larger and medium sized animals, with most studies indicating a preference for native ungulates averaging 90 kg (200 lb) at a minimum. Sambar, chital, barasingha, wild boar, gaur, nilgai and both water buffalo and domestic buffalo, in descending order of preference, are the tiger's favoured prey in India. Sometimes, they also prey on other predators, including other large species such as leopards, pythons, sloth bears and crocodiles. In Siberia the main prey species are manchurian wapiti and wild boar (the two species comprising nearly 80% of the prey selected) followed by sika deer, moose, roe deer, and musk deer. In Sumatra, sambar, Muntjac, wild boar, and Malayan tapir are predominantly preyed upon. In the former Caspian tiger's range, prey included saga antelope, camels, Caucasian wisent, yak, and wild horses. Like many predators, they are opportunistic and will eat much smaller prey, such as monkeys, peafowl's, other largish, ground-based birds, hares, porcupines and fish.
Adult elephants are too large to serve as common prey, but conflicts between tigers and elephants, with the huge elephant typically dominating the predator, do sometimes take place. A case where a tiger killed an adult Indian Rhinoceros has been observed, although adult rhinoceros are often ignored as potential prey due to a combination of very large size, a short temper and very thick skin, which render them a laborious and very difficult kill. Young elephant and rhino calves are occasionally taken. Tigers also sometimes prey on domestic animals such as dogs, cattle, horses, and donkeys. These individuals are termed cattle-lifters or cattle-killers in contrast to typical game-killers.
Old tigers, or those wounded and rendered incapable of catching their natural prey, have turned into man-eaters; this pattern has recurred frequently across India. An exceptional case is that of the Sundarbans, where healthy tigers prey upon fishermen and villagers in search of forest produce, humans thereby forming a minor part of the tiger's diet. Tigers will occasionally eat vegetation for dietary fiber, the fruit of the Slow Match Tree being favoured.
Tigers are thought to be nocturnal predators, hunting at night. However, in areas where humans are typically absent, they have been observed via remote controlled, hidden cameras hunting during the daylight hours. They generally hunt alone and ambush their prey as most other cats do, overpowering them from any angle, using their body size and strength to knock the prey off balance. Successful hunts usually require the tiger to almost simultaneously leap onto their quarry, knock it over and grab the throat or nape with its teeth. Even with their great masses, tigers can reach speeds of about 49–65 kilometres per hour (35–40 miles per hour), although they can only do so in short bursts, since they have relatively little stamina; consequently, tigers must be relatively close to their prey before they break their cover. If the prey catches wind of the tiger's presence before the moments of the pounce, the tiger will usually abandon the hunt rather than chase prey or battle it head-on. Tigers have great leaping ability; horizontal leaps of up to 10 m (33 ft) have been reported, although leaps of around half this amount are more typical. However, only one in twenty (or 5–10%) hunts, including any instances of stalking in proximity to potential prey, ends in a successful kill. An adult tiger can go up to two weeks without eating but then can gorge on up to 34 kg (75 lb) of flesh at one sitting. In captivity, adult tigers are fed 3 to 6 kg (6.6 to 13 lb) of meat a day. Due to their low hunting success rate, ability to go prolonged periods without food and naturally low population densities, tigers typically have little to no deleterious effect on the populations of the species they prey on. Several other large carnivores, such as gray wolves, spotted hyenas and lions, live in groups and need to capture relatively greater quantities of prey in order to feed and maintain stability in their respective packs, clans or prides.
When hunting large prey, tigers prefer to bite the throat and use their extremely powerful forelimbs to hold onto the prey, often simultaneously wrestling it to the ground. The tiger remains latched onto the neck until its prey dies of strangulation. By this method, gaurs and water buffalos weighing over a ton have been killed by tigers weighing about a sixth as much. Although they can kill healthy adults of large bovids weighing at least 1,000 kg (2,200 lb), tigers often select the calves or infirm of very large species. Large prey can be quite dangerous to tackle, with the great bulk and massive horns of large bovids, the strong legs and antlers of mature deer and the long, powerful tusks of boars all being potentially fatal to the tiger. No other extant land predator routinely takes on prey this large on their own. Whilst hunting sambars, which comprise up to 60% of their prey in India, tigers have reportedly called out a passable impersonation of the male sambar's rutting call in order to attract them.With small prey such as monkeys and hares, the tiger bites the nape, often breaking the spinal cord, piercing the windpipe, or severing the jugular vein or common carotid artery. Though rarely observed, some tigers have been recorded to kill prey by swiping with their paws, which are powerful enough to smash the skulls of domestic cattle, and break the backs of sloth bears. After killing their prey, tigers sometimes drag their prey to conceal it in vegetative coverage, usually pulling it by grasping with their mouths at the site of the killing bite (on the throat in large prey, on the nape in smaller prey). This too can require great physical strength. In one case, after it had killed an adult gaur, a tiger was observed to drag the massive carcass over a distance of 12 m (39 ft). When 13 men simultaneously tried to drag the same carcass later, they were unable to move it. During the 1980s, a tiger named "Genghis" in Ranthambhore National Park was observed frequently hunting prey through deep lake water, a pattern of behaviour that had not been previously witnessed in over 200 years of observations. Moreover, he appeared to be extraordinarily successful for a tiger, with as many as 20% of hunts ending in a kill. Tigers usually prefer to eat prey they've caught themselves but are not above eating carrion in times of scarcity and may even pirate prey from other large carnivores. Although predators typically avoid one another, if a prey item is under dispute or a serious competitor is encountered, displays of aggression are a regular occurrence. If these are not sufficient, the conflicts may come turn violent and tigers may kill such formidable competitors as leopards, striped hyenas, pythons and even crocodiles on occasion, In some cases, rather than being strictly competitive, the attacks by tigers on other large carnivores seem to be predatory in nature. Situations where smaller predators, such as badgers, lynxes and foxes are attacked, are almost certainly predatory. Interestingly, this species' closest living relative, the lion, deals with competing predators very differently, undoubtedly due to the fact that it lives in large prides. Lions do not treat other predators as prey, as does the tiger, but invests a good deal of time proactively track down other predators and killing them, then leaving their bodies uneaten. Lions kill competitors from honey badgers to spotted hyenas and, in protected areas of Africa, are the leading cause of mortality for African wild dogs and cheetahs. The tiger does not spend as much time tracking down other predators.
Occasionally, a large crocodile may attempt to predate a tiger. When seized by a crocodile, a tiger will strike at the reptile's eyes with its paws. When killing crocodiles, after stunning them about the face, tigers will flip the reptile's body over and disembowel it through the softer belly rather try to penetrate the thick, well-armoured upper hide. Eighteenth century Physician Oliver Goldsmith described the frequent conflicts between mugger crocodiles and tigers that occurred during that time. Thirsty tigers would frequently descend to the rivers to drink and on occasion were seized and killed by the muggers, though more often the tiger escaped and the reptile was disabled. Mature mugger crocodiles may target much the same prey as the tiger, including sambar and water buffalo. Occasionally, a mugger and a tiger will try to claim a carcass killed by either one, resulting in a "tug of war" at the water's edge until one of them comes away with it. A potentially more formidable foe is the larger, more aggressive Saltwater Crocodile, which the tiger rarely encounters outside of estuarial regions of eastern India. The first confirmed case of a saltwater crocodile predating an adult tiger occurred in that region in 2011. There is a second-hand account of a tiger killing a "small" saltwater crocodile.
The considerably smaller leopard dodges competition from tigers by hunting in different times of the day and hunting different prey. In India’s Nagarhole National Park, most prey selected by leopards was from 30 to 175 kg (66 to 390 lb) against a preference for prey weighing over 176 kg (390 lb) in the tigers. The average prey weight in the two respective big cats in India was 37.6 kg (83 lb) against 91.5 kg (202 lb). With relatively abundant prey, tigers and leopards were seen to successfully coexist without competitive exclusion or inter-species dominance hierarchies that may be more common to the savanna (where the leopard may co-exist with the lion). Tigers have been known to suppress wolf populations in areas where the two species coexist, mainly via competitive exclusion. There four proven records of Siberian tigers killing wolves and not eating them. Dhole packs have been observed to challenge the big cats in disputes over food and have even killed tigers in rare cases. However, tigers have also been observed killing multiple dholes at once and the dhole will typically only attack a tiger directly if the pack is quite large. Lone golden jackals expelled from their pack have been known to form commensal relationships with tigers. These solitary jackals, known as kol-bahl, will attach themselves to a particular tiger, trailing it at a safe distance in order to feed on the big cat's kills. A kol-bahl will even alert a tiger to a kill with a loud pheal. Tigers have been known to tolerate these jackals: one report describes how a jackal confidently walked in and out between three tigers walking together a few feet away from each other. When in the presence of a tiger, a golden jackal pack will emit a howl very different from its normal vocalization that is thought to function as a warning to other jackals.
Other than the rare large crocodile or large dhole pack, the only serious competitors to tigers are bears. Some bears, especially the brown bear of the North, will try to steal tigers' kills, although the tiger will sometimes defend its kill. However, in some cases, bears (especially cubs) are preyed upon by tigers. Although it hunts all its prey via ambush, tigers are especially cautious when handling bears, as many bears are capable of killing a tiger whilst defending themselves. Predation seems especially prevalent in India, where tigers may attack sloth bears. The sloth bears can be quite aggressive and will sometimes displace young tigers away from their kills or successfully defend themselves via counterattack. Despite this, sloth bears are killed with some regularity and react fearfully to the presence of tigers or even stimuli related to them (i.e. the call of the sambar deer due to the tiger's impersonation of it). Bears (Asiatic black bears and brown bears) make up 5–8% of the tiger's diet in the Russian Far East. Some accounts claim that the black bears more successfully avoid predation by tigers because they are skilled tree-climbers, although dietary research has contrarily indicated that the smaller, less aggressive black bear (comprising 4–6.5% of the tiger's local diet) is the more common prey species than the brown bear (at 1–1.5% of the diet).Siberian tigers and brown bears usually avoid confrontation but can sometimes be competitors, with dominance seemingly determined by the age, sex and size of the rivals rather than species. Older and larger males of both species tend to dominate in this interspecies conflict. Some brown bears, upon emerging from hibernation, follow tigers habitually in order to steal their kills. Tigers will kill brown bear cubs and even adults on some occasions, especially if they find the bears in their dens during the hibernation cycle or in periods of low prey density in the fall. There are also records of brown bears killing tigers up to the size of adult males, either in self-defence or in disputes over kills. Tigers may additionally predate the other bear species it encounters (or had encountered historically), which includes Giant pandas and sun bears, but information is very limited on such interactions.
Mating can occur all year round, but is generally more common between November and April. A female is only receptive for three to six days and mating is frequent during that time period. A pair will copulate frequently and noisily, like other cats. The gestation period can range from 93 to 112 days, although the average is 104–106 days. The litter size usually consists of anywhere from 1 to 6 cubs, though 2 to 3 is usually the norm. Cubs can weigh from 680 to 1,400 g (1.5 to 3.1 lb) each at birth and are born blind and helpless. The females rear them alone, with the birth site and maternal den being sheltered locations such as thickets, caves and rocky crevices. The father of the cubs generally takes no part in rearing them. Unrelated wandering male tigers may even kill cubs to make the female receptive, since the tigress may give birth to another litter within 5 months if the cubs of the previous litter are lost. The mortality rate of tiger cubs is fairly high – approximately half do not survive to be more than two years old. Few other predators attack tiger cubs due to the diligence and ferocity of the mother tiger. Beyond humans and other tigers, common causes of cub mortality are starvation, freezing and accidents.
There is generally a dominant cub in each litter, which tends to be male but may be of either sex. This cub generally dominates its siblings during play and tends to be more active, leaving its mother earlier than usual. The cubs open their eyes at 6 to 14 days old. At 8 weeks, the cubs may make short ventures out of the den with their mother, although they do not travel with her as she roams her territory until they are older. The cubs are nursed in total for a period of 3 to 6 months. Around the time they are weaned, they start regularly engaging in territorial walks with their mother. During this stage, the tigress's young are also taught how to hunt. The cubs are often capable (and nearly adult size) hunters by the time they are 11 months old. The cubs become independent around 18 months of age, but it is not until they are around 2–2½ years old that they fully separate from their mother. Females reach sexual maturity at 3–4 years, whereas males reach sexual maturity at 4–5 years.
Over the course of her life, a female tiger will typically give birth to an approximately equal number of male and female cubs. Tigers breed well in captivity, and the captive population in the United States may rival the wild population of the world. The known limit for lifespan in captivity is 26 years, and while captive animals usually outlive wild ones, it is thought that a wild adult tiger, with no natural predators as long as doesn't run afoul of humans, can likely live to a comparable age.
Intraspecific predatory relationships
Normally wild tigers, especially if they have no prior contact with humans, will actively avoid interactions with humans. However, according to some sources, tigers are thought to be responsible for more human deaths through direct attack than any other wild mammal. Attacks are occasionally provoked, as tigers will lash out after being injured while they themselves are hunted. Occasionally, attacks are provoked accidentally, as when a human surprises a tiger or inadvertently comes between a mother and her young. Occasionally human behavior will inadvertently provoke tiger attacks by triggering their natural instincts. In one case, a postman who delivered mail on foot in a rural region of India where interactions with tigers are commonplace, was not bothered by them for several years despite many interactions. Soon after the postman started to use a bicycle, the man was attacked by a tiger, theatrically having been instinctively provoked by the chase. Although humans are not regular prey for tigers, occasionally tigers will come to view people as prey. Such attacks tend to be particularly prevalent in areas where population growth, logging, and farming have put pressure on tiger habitats and reduced wild prey for them. Most man-eating tigers are old and missing teeth, acquiring a taste for humans because of their inability to capture their preferred prey. This was the case in the Champawat Tiger, a tigress found in Nepal and then India, that was found to have had two broken canines. She was responsible for an estimated 430 human deaths, the most attacks known to be perpetrated by a single wild animal per the Guinness Book, by the time she was shot in 1907 by Jim Corbett.
Unlike man-eating leopards, even established man-eating tigers will seldom enter human settlements, usually remaining at village outskirts. Nevertheless, attacks in human villages do occur. Tigers treat humans as they do other potential prey, engaging in a length stalking phase before pouncing from close range. Since they are nocturnal, many attacks occur at night while people are usually sleeping. Attacks are also common when people are working outdoors and are physically engaged in distracting tasks. Thanks to their natural predatory instincts, such as their use of stealth and surprise and their tendency to attack partially isolated people, early writings tend to profile man-eating tigers and other similarly-disposed big cats as "cowardly". Due to the size and power of the tiger, few humans survive when a predatory attack is carried out.
Reportedly, in the Singapore area (where tigers are now extirpated) in the 1840s, an estimated 1,000 fatalities occurred from tiger attacks. Man-eaters have been a particular problem in recent decades in India and Bangladesh, especially in Kumaon, Garhwal and the Sundarbans mangrove swamps of Bengal, where some healthy tigers have been known to hunt humans. Because of rapid habitat loss attributed to climate change, tiger attacks have increased in the Sundarbans.The Sundarbans area reportedly had 129 human deaths from tigers from 1969 to 1971. In the 10 years prior to that period, according to Chakrabarti (1984), humans were predated at an estimated rate of 100 per year in the Sudarban region, with a possible high of around 430 in some years of the 1960s. Unusually, in some years in the Sundarbans, more humans are killed by tigers than vica versa. In the year of 1972, India's production of honey and beeswax dropped by 50% when at least 29 people who gathered these materials were devoured.
Almost all tigers that are identified as man-eaters are quickly captured, shot, or poisoned. Current Indian wildlife protection laws state that animals must be saved unless the tiger is a repeat offender and no hope exists for rehabilitation. However, man-eating attacks may still lead to revenge killing of several tigers, including those not involved in the attack. On occasion, man-eating tigers are relocated to large nature preserves, with mixed success. In 1986 in the Sundarbans, since tiger almost always attack from the rear, the idea was implemented that masks with human faces on them be worn to the back of the head, on the theory that tigers will usually not carry through attacks if seen by their prey. This temporarily decreased the number of attack, though the tigers appeared to become habituated to the masks and attacks again increased in the following years.
Tigers kept in captivity retain wild instinct and, especially those in privately-owned collections where improper handling is more common, may attack humans. An estimated 1.75 fatal attacks occur per year in captivity, with at least 27 people killed or seriously injured in the United States by tigers from 1998 to 2001.In large, well-kept public zoos, tiger attacks on humans are very rare and tigers who associate with their zookeepers from birth may be docile and even affectionate towards their handlers once fully grown. However, most zoos are rightfully cautious and, when the tigers must be handled closely (such as medical procedures), it is a necessity to assure that tigers are fully unconscious from anesthesia.Tatiana, a female tiger, escaped from her enclosure in the San Francisco Zoo, killing one person and seriously injuring two more before being shot and killed by the police. The enclosure had walls that were lower than they were legally required to be, allowing the tiger to climb the wall and escape
Illegal trade in high-value Tiger products including
skins, bones, meat and tonics is a primary threat to Tigers, which has led to
their recent disappearance from broad areas of otherwise suitable habitat, and
continues at unsustainable rates.
Asia is a densely populated and rapidly developing region, bringing huge pressures to bear on the large wild areas required for viable Tiger populations. Conversion of forest land to agriculture and silviculture, commercial logging, and human settlement are the main drivers of Tiger habitat loss. With their substantial dietary requirements, Tigers require a healthy large ungulate prey base, but these species are also under heavy human subsistence hunting pressure and competition from domestic livestock.
Tiger attacks on livestock and people can lead to intolerance of Tigers by neighbouring communities and presents an ongoing challenge to managers to build local support for Tiger conservation. In some areas there have been many human deaths - for example, 41 people were killed by Tigers in the Sundarbans mangrove forest of Bangladesh during an 18-month period in 2001–2003 (Khan 2004).
Commercial hunting and traditional medicine
Historically, tigers have been hunted at a large scale so their famous striped skins could be collected. The trade in tiger skins peaked in 1960s, just before international conservation efforts took effect. By 1977, a tiger skin in an English market was considered to be worth $4,250 American dollars.
Many people in China and other parts of Asia have a belief that various tiger parts have medicinal properties, including as pain killers and aphrodisiacs. There is no scientific evidence to support these beliefs. The use of tiger parts in pharmaceutical drugs in China is already banned, and the government has made some offences in connection with tiger poaching punishable by death. Furthermore, all trade in tiger parts is illegal under the Convention on International Trade in Endangered Species of Wild Fauna and Flora and a domestic trade ban has been in place in China since 1993.
However, the trading of tiger parts in Asia has become a major black market industry and governmental and conservation attempts to stop it have been ineffective to date. Almost all black marketers engaged in the trade are based in China and have either been shipped and sold within in their own country or into Taiwan, South Korea or Japan. The Chinese subspecies was almost completely decimated by killing for commerce due to both the parts and skin trades in the 1950s through the 1970s. Contributing to the illegal trade, there are a number of tiger farms in the country specialising in breeding the cats for profit. It is estimated that between 5,000 and 10,000 captive-bred, semi-tame animals live in these farms today. However, many tigers for traditional medicine black market are wild ones shot or snared by poachers and may be caught anywhere in the tiger's remaining range (from Siberia to India to the Malay Peninsula to Sumatra). In the Asian black market, a tiger penis can be worth the equivalent of around $300 U.S. dollars. In the years of 1990 through 1992, 27 million products with tiger derivatives were found
In 2010, the Year of the Tiger on the Asian lunar calendar,
Tigers were the focus of substantial conservation effort and investment. At a
“Tiger Summit” held in St. Petersburg, Russia in November 2010, the 13 Tiger
Range Countries adopted a Global Tiger Recovery Program (GTRP 2010). The goal is
to effectively double the number of wild Tigers by 2022 through actions to: i)
effectively preserve, manage, enhance and protect Tiger habitats; ii) eradicate
poaching, smuggling and illegal trade of Tigers, their parts and derivatives;
iii) cooperate in transboundary landscape management and in combating illegal
trade; iv) engage with indigenous and local communities; v) increase the
effectiveness of Tiger and habitat management; and vi) restore Tigers to their
former range. The Tiger Summit was attended by Heads of State including Russia,
China, Laos, Nepal and Bangladesh, and represents a policy commitment to Tiger
conservation of unprecedented significance.
The future of Tiger range depends upon the Asian governments creating effective Tiger landscapes by conserving large areas of suitable habitat. Within these landscapes, the most urgent need is to first secure the source sites—protected areas with viable Tiger populations—where most of the global Tiger population is now clustered, and many of which are currently too threatened to deliver their potential as the wellspring of species recovery (Walston et al. 2010b