Panthera tigris
tiger

The range of tigers once extended across Asia from eastern Turkey and the Caspian Sea south of the Tibetan plateau eastward to Manchuria and the Sea of Okhotsk. Tigers were also found in northern Iran, Afghanistan, the Indus valley of Pakistan, Laos, Thailand, Vietnam, Cambodia, Malaysia, and the islands of Java and Bali. Tigers are now extinct or nearly extinct in most of these areas. Populations remain relatively stable in northeastern China, Korea, Russia, and parts of India and the Himalayan region. ()

There are eight recognized subspecies of Panthera tigris. Siberian tigers, P. t. altaica, are currently found only in a small part of Russia, including the Amurussuri region of Primorye and Khabarovsk. Bengal tigers, P. t. tigris, are found in India, Bangladesh, Nepal, Bhutan, and China. Indochinese tigers, P. t. corbetti, are found in Cambodia, China, Laos, Malaysia, Myanmar, Thailand, and Vietnam. South China tigers, P. t. amoyensis, are found in three isolated areas in southcentral China. Sumatran tigers, P. t. sumatrae, are found only on the Indonesian island of Sumatra. Bali tigers (P. t. balica), Javan tigers (P. t. sondaica), and Caspian tigers (P. t. virgata) are thought to be extinct. Those subspecies occurred on the islands of Bali (P. t. balica), Java (P. t. sondaica), and in Turkey, the Transcaucasus region, Iran, and central Asia (P. t. virgata). ()

Tigers live in a wide variety of habitats, suggested by their distribution across a wide range of ecological conditions. They are known to occur in tropical lowland evergreen forest, monsoonal forest, dry thorn forest, scrub oak and birch woodlands, tall grass jungles, and mangrove swamps. Tigers are able to cope with a broad range of climatic variation, from warm moist areas, to areas of extreme snowfall where temperatures may be as low as –40 degrees Celsius. Tigers have been found at elevations of 3,960 meters. In general, tigers require only some vegetative cover, a source of water, and sufficient prey. ()

Tigers have a reddish-orange coat with vertical black stripes along the flanks and shoulders that vary in size, length, and spacing. Some subspecies have paler fur and some are almost fully white with either black or dark brown stripes along the flanks and shoulders. The underside of the limbs and belly, chest, throat, and muzzle are white or light. White is found above the eyes and extends to the cheeks. A white spot is present on the back of each ear. The dark lines about the eyes tend to be symmetrical, but the marks on each side of the face are often asymmetrical. The tail is reddish-orange and ringed with several dark bands. ()

Body size and morphology varies considerably among subspecies of tigers. Siberian tigers, also know as Amur tigers (P. t. altaica), are the largest. Male Siberian tigers can grow to 3.7 meters and weigh over 423 kg; females are up to 2.4 meters in length and 168 kg. Male Indochinese tigers (P. t. corbetti), though smaller than Siberian tigers in body size at 2.85 meters in length and 195 kg, have the longest skull of all tiger subspecies, measuring 319 to 365 mm. Sumatran tigers (P. t. sumatrae) are the smallest living subspecies. Male Sumatran tigers measure 2.34 meters and weigh 136 kg; females measure 1.98 meters and weigh 91 kg. ()

Tigers are powerful animals, one is known to have dragged a gaur bull weighing 700 kg. Tigers have short, thick necks, broad shoulders, and massive forelimbs, ideal for grappling with prey while holding on with long retractible claws and broad forepaws. A tiger’s tongue is covered with hard papillae, to scrape flesh off the bones of prey. ()

All tigers have a dental formula of 3/3, 1/1, 3/2, 1/1. Bengal tigers (P. t. tigris) have the longest canines of any living large cat; from 7.5 to 10 cm in length. A tiger's skull is robust, short, and broad with wide zygomatic arches. The nasal bones are high, projecting little further than the maxillary, where the canines fit. Tigers have a well-developed sagittal crest and coronoid processes, providing muscle attachment for their strong bite. ()

Tigers usually live 8 to 10 years in the wild, although they can reach ages into their 20's. In captivity tigers have been known to live up to 26 years old, although a typical captive lifespan is 16 to 18 years. It is estimated that most adult tigers die as a result of human persecution and hunting, although their large prey can occasionally wound them fatally. Young tigers face numerous dangers when they disperse from their mother's home range, including being attacked and eaten by male tigers. Some researchers estimate a 50% survival rate for young tigers. ()

Tigers are solitary, the only long-term relationship is between a mother and her offspring. Tigers are most active at night, when their wild ungulate prey are most active, although they can be active at any time of the day. Tigers prefer to hunt in dense vegetation and along routes where they can move quietly. In snow, tigers select routes on frozen river beds, in paths made by ungulates, or anywhere else that has a reduced snow depth. Tigers have tremendous leaping ability, being able to leap from 8 to 10 meters. Leaps of half that distance are more typical. Tigers are excellent swimmers and water doesn't usually act as a barrier to their movement. Tigers can easily cross rivers as wide as 6-8 km and have been known to cross a width of 29 km in the water. Tigers are also excellent climbers, using their retractible claws and powerful legs. ()

Home Range

Home range sizes vary depending on the density of prey. Female Indian tigers (P. t. tigris) have home range sizes from 200 to 1000 square kilometers (range 64 to 9252 km2); a male's home range averages between 2 to 15 times larger. Within their home range tigers maintain several dens, often among dense vegetation or in a cave, cavity under a fallen tree, or in a hollow tree. Tigers often defend exclusive home ranges, but they have also been known to peacefully share home ranges or wander permanently, without any home range. Tigers may cover as much as 16 to 32 kilometers in a single night. ()

Communication among tigers is maintained by scent markings, visual signals, and vocalization. Scent markings are deposited in the form of an odorous musky liquid that is mixed with urine and sprayed on objects like grass, trees, or rocks. A facial expression called “flehmen” is often associated with scent detection. During flehmen, the tongue hangs over the incisors, the nose is wrinkled, and the upper canines are bared. Flehmen is commonly seen in males that have just sniffed urine, scent marks, an estrous tigress, or a cub of their own species. ()

Visual signals made by tigers include spots that have been sprayed, scrapes made by raking the ground, and claw marks left on trees or other objects. Schaller (1967) described a “defense threat” facial expression observed when a tiger is attacking. This involved pulling the corners of the open mouth back, exposing the canines, fattening the ears, and enlarging the pupils of the eyes. The spots on the back of their ears and their pattern of stripes may also be used in intraspecific communication. ()

Tigers can also communicate vocally with roars, growls, snarls, grunts, moans, mews, and hisses. Each sound has its own purpose, and appears to reflect the tiger's intent or mood. For example, a tiger’s roar is usually a signal of dominance; it tells other individuals how big it is and its location. A moan communicates submission. The ability of tigers to roar comes from having a flexible hyoid apparatus and vocal fold with a thick fibro- elastic pad that allows sound to travel long distances. ()

Tigers prefer to hunt at night, when their ungulate prey are most active. In a study done in India by Schaller (1967), tigers were most active before 0800 and after 1600 hours. Tigers are thought to locate their prey using hearing and sight more than olfaction (Schaller, 1967). They use a stealthy approach, taking advantage of every rock, tree and bush as cover and rarely chase prey far. Tigers are silent, taking cautious steps and keeping low to the ground so they are not sighted or heard by the prey. They typically kill by ambushing prey, throwing the prey off balance with their mass as they leap onto it. Tigers are successful predators but only 1 out of 10 to 20 attacks result in a successful hunt. ()

Tigers use one of two tactics when they get close enough to kill. Small animals, weighing less than half the body weight of the tiger, are killed by a bite to the back of the neck. The canines are inserted between the neck vertebrae forcing them apart and breaking the spinal cord. For larger animals, a bite to the throat is used to crush the animal’s trachea and suffocate it. The throat bite is the safer killing tactic because it minimizes any physical assault the tiger may receive while trying to kill its prey. After the prey is taken to cover, tigers feed first on the buttocks using the carnassials to rip open the carcass. As the tiger progresses it opens the body cavity and removes the stomach. Not all of the prey is eaten; some parts are rejected. Prey are usually dragged to cover and may be left there and revisited over several days. ()

The majority of the tiger diet consists of various large ungulate species, including sambar (Rusa unicolor), chital (Axis axis), hog deer (Axis porcinus), barasingha (Rucervus duvaucelii), barking deer (Muntiacus muntjak), elk (Cervus elaphus), sika deer (Cervus nippon), Eurasian elk (Alces alces), roe deer (Capreolus capreolus), muskdeer (Moschus moschiferus), nilgai (Boselaphus tragocamelus), black buck (Antilope cervicapra), gaur (Bos frontalis), banteng (Bos javanicus), water buffalo (Bubalus bubalis), and wild pigs (Sus). Domestic ungulates are also taken, including cattle (Bos taurus), water buffalo (Bubalus bubalis), horses (Equus caballus), and goats (Capra hircus). In rare cases tigers attack Malayan tapirs (Tapirus indicus), Indian elephants (Elephas maximus), and young Indian rhinoceroses (Rhinoceros unicornis). Tigers regularly attack and eat brown bears (Ursus arctos), Asiatic black bears (Ursus thibetanus), and sloth bears (Melursus ursinus). Smaller animals are sometimes taken when larger prey is unavailable, this includes large birds such as pheasants (Phasianinae), leopards (Panthera pardus), fish, crocodiles (Crocodylus), turtles, porcupines (Hystrix), rats, and frogs. A very few tigers begin to hunt humans (Homo sapiens). Tigers will eat between 18 and 40 kg of meat when they successfully take large prey, they do not typically eat every day. ()

Tigers have no natural predators, except for humans. Adult tigers are potential predators of younger cubs. ()

Tigers help regulate populations of their large herbivore prey, which put pressure on plant communities. Because of their role as top predators, they may be considered keystone species. ()

Tiger parasites include the nematode, trematode, and cestode worms: Paragonimus westermani, Toxocara species, Uiteinarta species, Physaloptera praeputhostoma, Dirofilaria species, Gnathostoma spinigerum, Diphyllobothrium erinacei, Taenia bubesei, and Taenia pisiformis. Ticks known from tigers are Boophilus calcaratus, Dermacentor silvarum, Hyalomma detritum, Hyalomma kumari, Hyalomma marginata, and Rhipicelphalus turanicus.

Normally tigers avoid human contact, very rarely tigers may become “man eaters”. A man-eating tigress was rumored to have killed over 430 people, including 234 over the course of four years. It is thought that man-eating tigers are those that cannot effectively prey on large ungulated because they have become crippled, are old, or no longer have suitable native habitat and prey available. Because human populations are rapidly increasing, competition over natural resources is increasing pressure on tigers and their habitat and increasing the likelihood of negative human-tiger interactions. ()

Live tigers are of economic importance in zoos where they are displayed to the public and in wildlife areas where they may bring in tourism. Tigers are illegally killed for their fur to make rugs and wall hangings. In addition, for more than 3000 years traditional Chinese medicine has used tiger parts to treat sickness and injury. The humerus (upper leg bone), for example, has been prescribed to treat rheumatism even though there is no evidence that it has any affect on the disease. Some believe that tiger bones will help them become as strong and ferocious as the tiger. ()

Siberian (P. t. altaica), South China (P. t. amoyensis), and Sumatran tigers (P. t. sumatrae) are all critically endangered. Bengal (P. tigris tigris) and Indochinese tigers (P. tigris corbetti) are endangered. Bali (P. t. balica), Javan (P. t. sondaica), and Caspian tigers (P. tigris virgata) are extinct. The specific threats to tigers vary regionally, but human persecution, hunting, and human-induced habitat destruction are universal factors in threatening tiger populations. ()

Panthera tigris has 38 chromosomes. The karyotype has 16 pairs of metacentric and submetacentric autosomes and two pairs of acrocentric autosomes. The X chromosome is a medium-sized metacentric and the Y chromosomes is a small metacentric.

Maltese tigers (sometimes referred to as P. t. melitensis, although they are not a true subspecies) are a variety of tiger that results from inbreeding. Maltese tigers have white fur with grey hues, making them look blue from a distance. So called 'white tigers' result when a cub is born with two recessive forms of a gene, also the result of inbreeding. White tigers suffer from many problems including eye weakness, sway backs, and twisted necks. ()