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Jumat, 06 Juli 2007

Tiger


Tigers (Panthera tigris) are mammals of the Felidae family, one of four "big cats" in the Panthera genus, and native to the mainland of southeastern Asia. They are apex predators and the largest feline species in the world, comparable in size to the biggest fossil felids. The Bengal Tiger is the most common subspecies of tiger, constituting approximately 80% of the entire tiger population, and is found in India, Bangladesh, Bhutan, Myanmar, and Nepal. An endangered species, the majority of the world's tigers now live in captivity.
Physical characteristics
Tigers are the heaviest cats found in the wild, but the subspecies differ strongly in size. Large male Siberian Tigers (Panthera tigris altaica) can reach a total length of 3,5 m and a weight of 300 kg. Usually they reach a head and body length of 190-220 cm and a weight of 250 kg. The heaviest Indian Tiger (P. t. tigris), which is confirmed through reliable sources weighed 258 kg (570 lb). Reports of tigers weighing far more than 300 kg are mentioned in literature, but none of these cases is confirmed[9]. Females are smaller those of the Siberian or Indian subspecies weigh only between 100 and 167 kg. Isle tigers like the sumatran subspecies (P. t. sumatrae) are much smaller than mainland tigers and weigh usually only 100-140 kg in males and 75-110 kg in females. The extinct bali tiger (P. t. balica) was even smaller with a weight of 90-100 kg in males and 65-80 kg in females.
Most tigers have orange coats, a fair (whitish) medial and ventral area and stripes that vary from brown or hay to pure black. The form and density of stripes differs between subspecies, but most tigers have in excess of 100 stripes. The pattern of stripes is unique to each animal, and thus could potentially be used to identify individuals, much in the same way as fingerprints are used to identify people. This is not, however, a preferred method of identification, due to the difficulty of recording the stripe pattern of a wild tiger. It seems likely that the function of stripes is camouflage, serving to hide these animals from their prey. The stripe pattern is found on a tiger's skin and if shaved, its distinctive camouflage pattern would be preserved.
Like most cats, tigers are believed to have some degree of colour vision.
There is a well-known mutation that produces the white tiger, an animal which is rare in the wild, but widely bred in zoos due to its popularity. The white tiger is not a separate sub-species, but only a colour variation. There are also unconfirmed reports of a "blue" or slate-coloured tiger, and largely or totally black tigers, and these are assumed, if real, to be intermittent mutations rather than distinct species. Similar to the lion, the tiger has the ability to roar.
Biology and ecology
Adult tigers are territorial and fiercely defensive. A tigress may have a territory of 20 km² while the territories of males are much larger, covering 60-100 km². Male territories may overlap those of many females, but males are intolerant of other males within their territory. Because of their aggressive nature, territorial disputes can be violent and may end in the death of one of the males, though deaths are uncommon. Most encounters between tigers end without physical incident. To identify his territory the male marks trees by spraying urine and anal gland secretions on trees as well as by marking trails with scat. Males show a behaviour called flehmen, a grimacing face, when identifying a female's reproductive condition by sniffing their urine markings.
A female is only receptive for a few days and mating is frequent during that time period. A pair will copulate frequently and noisily, like other cats. The gestation period is 103 days and 3–4 cubs of about 1 kg (2 lb) each are born. The females rear them alone. Wandering male tigers may kill cubs to make the female receptive. At 8 weeks, the cubs are ready to follow their mother out of the den. The cubs become independent around 18 months of age, but it is not until they are around 2–2½ years old that they leave their mother. The cubs reach sexual maturity by 3–4 years of age. The female tigers generally own territory near their mother, while males tend to wander in search of territory, which they acquire by fighting and eliminating another male. Over the course of her life, a female tiger will 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.
In the wild, tigers mostly feed on larger ungulates, but they also take smaller prey and tigers have been known to kill crocodiles on occasion, [11][12][13] although predation is rare and the predators typically avoid one another. Siberian tigers and brown bears are a serious threat to each other and both tend to avoid each other. Statistically though, the Siberian tiger has been the more successful in battles between the two animals because bears taken by tigers are often smaller sized bears; however, tigers can and do kill larger brown bears. Even female tigers, which are considerably smaller than male tigers, are capable of taking down and killing adult gaurs by themselves. Sambar, wild boar and gaur are the tiger's favoured prey in India. Young elephant and rhino calves are occasionally taken when they are left unprotected by their herds. A case where a tiger killed an adult female Indian rhino has been observed. [14]
Tigers prefer large prey such as sambar, gaur and wild water buffalo because they provide more meat and last for many days, avoiding the need for another hunt. In all of their range, tigers are the top predators and do not compete with other carnivores other than the dhole or Indian wild dog, which makes up for its relative lack of strength by numbers. They do not prey on large animals such as adult elephants and rhinos, although they will prey on their young whenever they have an opportunity. However, a desperate tiger will attack anything it regards as potential food, including humans.
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. In recent times, camera trapping has been used 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.

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