هوية إماراتية
08-03-2010, 08:36 PM
Rattlesnakes are a group of venomous (http://en.wikipedia.org/wiki/Venomous_snake) snakes (http://en.wikipedia.org/wiki/Snakes), genera (http://en.wikipedia.org/wiki/Genus) Crotalus (http://en.wikipedia.org/wiki/Crotalus) and Sistrurus (http://en.wikipedia.org/wiki/Sistrurus). They belong to the subfamily of venomous snakes known commonly as pit vipers (http://en.wikipedia.org/wiki/Crotalinae).
Overview
There are approximately thirty species of rattlesnake (http://en.wikipedia.org/wiki/List_of_rattlesnake_species_and_subspecies), with numerous subspecies. They receive their name for the rattle (http://en.wikipedia.org/wiki/Rattlesnake#Rattle) located at the end of their tails. The rattle is used as a warning device when threatened. The scientific name Crotalus derives from the Greek (http://en.wikipedia.org/wiki/Greek_language), κρόταλον, meaning "castanet (http://en.wikipedia.org/wiki/Castanet)". The name Sistrurus is the Latinized (http://en.wikipedia.org/wiki/Latin_language) form of the Greek (http://en.wikipedia.org/wiki/Greek_language) word for "tail rattler" (Σείστρουρος, Seistrouros) and shares its root with the ancient Egyptian (http://en.wikipedia.org/wiki/Egypt) musical instrument, the sistrum (http://en.wikipedia.org/wiki/Sistrum), a type of rattle. Most rattlesnakes mate in the spring. All species give live birth (http://en.wikipedia.org/wiki/Live_birth), rather than laying eggs. The young are self-sufficient from birth. Since they do not need their mother after birth, the mother does not remain with her young. However, at least one captive study has demonstrated that females and their neonates show some level of affinity for each other's company and will cross barriers to reunite if separated.
Contrary to popular myth, rattlesnakes are not deaf (http://en.wikipedia.org/wiki/Deaf). In fact, the structure of their inner ears (http://en.wikipedia.org/wiki/Inner_ear) is very much like that of other reptiles. They do, however, lack external ears. Sound (whether from air or ground vibration) is transmitted to the snake's inner ear via bone and muscle.
Prey
Rattlesnakes consume mice, rats, small birds and other small animals. They subdue their prey (http://en.wikipedia.org/wiki/Prey) quickly with a venomous (http://en.wikipedia.org/wiki/Venom) bite as opposed to constricting (http://en.wikipedia.org/wiki/Constriction). The venom will immediately stun or kill typical prey. Rattlesnake venom can kill in 20 seconds, but a rattlesnake will follow prey that does not quickly succumb to the venom and attempts to escape. Rattlers are known to strike at distances up to two-thirds their body length.
Reproduction
Although many kinds of snakes are oviparous (http://en.wikipedia.org/wiki/Oviparous) (lay eggs), rattlesnakes are ovoviviparous (http://en.wikipedia.org/wiki/Ovoviviparous) – the female retains the eggs in her body and they hatch as they are laid or soon afterwards; or viviparous (http://en.wikipedia.org/wiki/Viviparous) (give birth to live young). Baby snakes are ready to go as soon as they are hatched or born. There is little to no parental care of the newborn snakes.
Rattle
http://upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Rattle.jpg/220px-Rattle.jpg (http://en.wikipedia.org/wiki/File:Rattle.jpg)
(http://en.wikipedia.org/wiki/File:Rattle.jpg)
The rattle of a rattlesnake
http://upload.wikimedia.org/wikipedia/commons/thumb/b/bd/Britannica_Rattlesnake_Rattle.jpg/220px-Britannica_Rattlesnake_Rattle.jpg (http://en.wikipedia.org/wiki/File:Britannica_Rattlesnake_Rattle.jpg)
(http://en.wikipedia.org/wiki/File:Britannica_Rattlesnake_Rattle.jpg)
Drawing of the rattle
http://upload.wikimedia.org/wikipedia/en/thumb/7/70/Rattlesnake_rattles.jpg/220px-Rattlesnake_rattles.jpg (http://en.wikipedia.org/wiki/File:Rattlesnake_rattles.jpg)
(http://en.wikipedia.org/wiki/File:Rattlesnake_rattles.jpg)
Rattlesnake rattle
The rattle is composed of a series of nested, hollow beads which are actually modified scales from the tail tip. Each time the snake sheds its skin, a new rattle segment is added. They may shed their skins several times a year depending on food supply and growth rates. Newborn rattlesnakes (pre-button) do not have functional rattles; it is not until after they have shed their skin for the first time that they gain an additional bead, which beats against the first bead, known as the button, to create the rattling sound. Adult snakes may lose their rattles on occasion, but more appear at each molting (http://en.wikipedia.org/wiki/Molt). If the rattle absorbs enough water in wet weather, it will not make noise.
Safety and identification
http://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Crotalus_viridis_Southern_Pacific_Rattlesnake_Juve nile.jpg/220px-Crotalus_viridis_Southern_Pacific_Rattlesnake_Juve nile.jpg (http://en.wikipedia.org/wiki/File:Crotalus_viridis_Southern_Pacific_Rattlesnake _Juvenile.jpg)
(http://en.wikipedia.org/wiki/File:Crotalus_viridis_Southern_Pacific_Rattlesnake _Juvenile.jpg)
Juvenile Southern Pacific Rattlesnake (http://en.wikipedia.org/wiki/Southern_Pacific_Rattlesnake) in California (http://en.wikipedia.org/wiki/California)
Different species of rattlesnake vary significantly in size, territory, markings, and temperament. If the rattlesnake is not cornered or imminently threatened, it will usually attempt to flee from encounters with humans, but will not always do so. Bites often occur when humans startle the snake or provoke it. Those bitten while provoking rattlesnakes have usually underestimated the range (roughly two-thirds of its total length) and speed with which a coiled snake can strike (literally faster than the human eye can follow). Heavy boots and long pants reinforced with leather or canvas are recommended for hikers in areas known to harbor rattlesnakes.
Guides are available through booksellers, libraries, and local conservation and wildlife management agencies that aid hikers and campers in identifying rattlesnakes. The advice given is to avoid contact with rattlesnakes by remaining observant and not approaching the animals. Hikers are advised to be particularly careful when negotiating fallen logs or boulders and when near rocky outcroppings and ledges where rattlesnakes may be hiding or sunning themselves. However, snakes will occasionally sun themselves in the middle of a trail, so such areas are not the only places where they are encountered. When encountering a rattlesnake on a trail, hikers are advised to keep their distance and allow the snake room to retreat.
Bites
See also: Snakebite (http://en.wikipedia.org/wiki/Snakebite)
http://upload.wikimedia.org/wikipedia/en/thumb/2/22/Rattlesnakesign.jpg/220px-Rattlesnakesign.jpg (http://en.wikipedia.org/wiki/File:Rattlesnakesign.jpg) http://bits.wikimedia.org/skins-1.5/common/images/magnify-clip.png (http://en.wikipedia.org/wiki/File:Rattlesnakesign.jpg)
A rattlesnake warning sign
Rattlesnakes are born with fully functioning fangs capable of injecting venom and can regulate the amount of venom they inject when biting. Generally they deliver a full dose of venom to their prey, but may deliver less venom or none at all when biting defensively. A frightened or injured snake may not exercise such control. Young snakes are to be considered more dangerous, as they have less control over the amount of venom they inject.[1] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-0) A young rattlesnake will often simply inject all its venom, which might be a lethal dose, depending on the size of the bitten animal.
[edit (http://en.wikipedia.org/w/index.php?title=Rattlesnake&action=edit§ion=7)] Toxicity
Most species of rattlesnakes have hemotoxic (http://en.wikipedia.org/wiki/Hemotoxin) venom, destroying tissue, degenerating organs and causing coagulopathy (http://en.wikipedia.org/wiki/Coagulopathy) (disrupted blood clotting). Some degree of permanent scarring is very likely in the event of a venomous bite, even with prompt, effective treatment, and a severe envenomation (http://en.wikipedia.org/wiki/Envenomation), combined with delayed or ineffective treatment, can lead to the loss of a limb or death. Thus, a rattlesnake bite is always a potentially fatal injury. Untreated rattlesnake bites, especially from larger species, are very often fatal. However, antivenom (http://en.wikipedia.org/wiki/Antivenom), when applied in time, reduces the death rate to less than 4%. It is estimated that between 7,000 and 8,000 people are bitten by venomous snakes in the United States each year, and about five of those die.[2] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-1) About 72% of those bitten by rattlesnakes are male.[3] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-2)
Some rattlesnakes, especially the tropical species, have neurotoxic (http://en.wikipedia.org/wiki/Neurotoxin) venom. A bite from these snakes can interfere with or shut down parts of the nervous system. In the U.S. the Mojave Rattlesnake (http://en.wikipedia.org/wiki/Mojave_Rattlesnake) (Crotalus scutulatus) in Arizona (http://en.wikipedia.org/wiki/Arizona) and parts of California (http://en.wikipedia.org/wiki/California) has a neurotoxic venom component known as Mojave Type A toxin. The current antivenom, (FDA (http://en.wikipedia.org/wiki/Food_and_Drug_Administration)-approved in October, 2000) known as CroFab (http://en.wikipedia.org/wiki/CroFab), contains antibodies to Mojave A and B toxins as well as the toxins of most other U.S. pit vipers (http://en.wikipedia.org/wiki/Pit_viper). Mojave A toxin has been identified present in the venoms of other species of rattlesnakes on occasion. Neurotoxins cause neurological symptoms, paralysis and could result in death due to respiratory paralysis. In the U.S., Central and South America there are another group of neurotoxic snakes known as the Coral Snakes (http://en.wikipedia.org/wiki/Coral_Snake), not related to rattlesnakes but more closely related to the cobra (http://en.wikipedia.org/wiki/Cobra) family of Africa and Asia. These snakes can also cause death due to respiratory paralysis if not properly treated.
The Common Kingsnake (Lampropeltis getula (http://en.wikipedia.org/wiki/Lampropeltis_getula)), a constrictor (http://en.wikipedia.org/wiki/Constrictor), is famous for being largely immune (http://en.wikipedia.org/wiki/Immune) to the venom of rattlesnakes and other vipers (http://en.wikipedia.org/wiki/Viperidae),[4] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-3) and therefore rattlesnakes form part of this snake's natural diet in the wild.
First aid
When a bite occurs, the amount of venom injected cannot be gauged easily. Symptoms and swelling may occur quickly, and may cause death easily but in some cases hours may pass before serious effects appear.
Experienced health workers typically gauge envenomation in stages ranging from 0, when there is no evident venom, to 5, when there is a life-threatening amount of venom present. The stages reflect the amount of bruising and swelling around the fang marks and the speed with which that bruising and swelling progresses. In more severe envenomation cases (stage 4 or 5) there may also be proximal symptoms, such as lip-tingling, dizziness, bleeding, vomiting, or shock. Difficulty breathing, paralysis, drooling, and massive haemorrhaging are also common symptoms.
Quick medical attention is critical, and treatment typically requires antivenin/antivenom (http://en.wikipedia.org/wiki/Antivenom) to block the tissue destruction, nerve effects, and blood-clotting disorders common with rattlesnake venom. Most medical experts recommend keeping the area of the bite below the level of the heart. It is important to keep a snake bite victim calm in order to avoid elevating their heart rate and accelerating the circulation of venom within the body. Untrained individuals should not attempt to make incisions at or around bite sites, or to use tourniquets, as either treatment may be more destructive than the envenomation itself.
Any bite from a rattlesnake should be regarded as a life-threatening medical emergency (http://en.wikipedia.org/wiki/Medical_emergency) that requires immediate hospital treatment from trained professionals.
Human consumption
Rattlesnakes are also a popular food in some southeastern and southwestern American cuisines and are sometimes sold in specialty meat shops.[5] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-4) The flavor has been characterized by one vendor as "delicate" and "resembling chicken (http://en.wikipedia.org/wiki/Tastes_like_chicken)";[6] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-5) and by journalist Alistair XXXXX (http://en.wikipedia.org/wiki/Alistair_XXXXX) as "just like chicken, only tougher."[7] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-6) Others have compared the flavor to a wide range of other meats, including veal, frog, tortoise, quail, fish, rabbit, and even canned tuna.[8] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-7)
Human consumption
Rattlesnakes are also a popular food in some southeastern and southwestern American cuisines and are sometimes sold in specialty meat shops.[5] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-4) The flavor has been characterized by one vendor as "delicate" and "resembling chicken (http://en.wikipedia.org/wiki/Tastes_like_chicken)";[6] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-5) and by journalist Alistair XXXXX (http://en.wikipedia.org/wiki/Alistair_XXXXX) as "just like chicken, only tougher."[7] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-6) Others have compared the flavor to a wide range of other meats, including veal, frog, tortoise, quail, fish, rabbit, and even canned tuna.[8] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-7)
اتمنى اني اكون ساعدتكم . ، ما عليكم الا تمسحون الأرقام اللي مثل ها : ~ > [5] (http://en.wikipedia.org/wiki/Rattlesnake#cite_note-4)
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وتعدلونه شوي وتسلمونه
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وبالتوفيج
(http://en.wikipedia.org/wiki/Rattlesnake#cite_note-4)
{SOSO}
19-03-2010, 01:08 PM
The tiger (Panthera tigris) is a member of the Felidae family; the largest of the four "big cats" in the genus Panthera.[4] Native to much of eastern and southern Asia, the tiger is an apex predator and an obligate carnivore. Reaching up to 3.3 metres (11 ft) in total length and weighing up to 300 kilograms (660 pounds), the larger tiger subspecies are comparable in size to the biggest extinct felids.[5][6] Aside from their great bulk and power, their most recognisable feature is a pattern of dark vertical stripes that overlays near-white to reddish-orange fur, with lighter underparts. The most numerous tiger subspecies is the Bengal tiger while the largest subspecies is the Siberian tiger.
Highly adaptable, tigers range from the Siberian taiga, to open grasslands, to tropical mangrove swamps. They are territorial and generally solitary animals, often requiring large contiguous areas of habitat that support their prey demands. This, coupled with the fact that they are endemic to some of the more densely populated places on earth, has caused significant conflicts with humans. Of the nine subspecies of modern tiger, three are extinct and the remaining six are classified as endangered, some critically so. The primary direct causes are habitat destruction and fragmentation, and hunting. Their historical range once stretched from Mesopotamia and the Caucasus through most of South and East Asia. Today it has been radically reduced. While all surviving species are under formal protection, poaching, habitat destruction and inbreeding depression continue to threaten the species.
Tigers are among the most recognisable and popular of the world's charismatic megafauna. They have featured prominently in ancient mythology and folklore, and continue to be depicted in modern films and literature. Tigers appear on many flags and coats of arms, as mascots for sporting teams, and as the national animal of several Asian nations, including India [7].
Naming and etymology
The word "tiger" is taken from the Greek word "tigris", which is possibly derived from a Persian source meaning "arrow", a reference to the animal's speed and also the origin for the name of the Tigris river.[8][9] In American English, "Tigress" was first recorded in 1611. It was one of the many species originally described, as Felis tigris, by Linnaeus in his 18th century work, Systema Naturae.[3][10] The generic component of its scientific designation, Panthera tigris, is often presumed to derive from Greek pan- ("all") and theron ("beast"), but this may be a folk etymology. Although it came into English through the classical languages, panthera is probably of East Asian origin, meaning "the yellowish animal," or "whitish-yellow."[11]
A group of tigers[12] is rare (see below), but when seen together is termed a 'streak' or an 'ambush'.
Range of the tiger including the western part 1900 and 1990Range and habitat
This section does not cite any references or sources.
Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2009)
In the past, the tiger's range was widespread in Asia, from the Caucasus and the Caspian Sea to Siberia and Indonesia. During the 19th century, these cats completely vanished from western Asia, and became restricted to isolated pockets in the remaining parts of their range. Today, their range is fragmented, and extends from India in the west to China and Southeast Asia in the east. The northern limit is close to the Amur River in south eastern Siberia. The only large island inhabited by tigers today is Sumatra. Tigers vanished from Java and Bali during the 20th century, and in Borneo are known only from fossil remains.
Tiger habitats will usually include sufficient cover, proximity to water, and an abundance of prey sources. Bengal Tigers live in many types of forests, including wet; evergreen; the semi-evergreen of Assam and eastern Bengal; the mangrove forest of the Ganges Delta; the deciduous forest of Nepal, and the thorn forests of the Western Ghats. 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. Among the big cats, only the tiger and jaguar are strong swimmers; tigers are often found bathing in ponds, lakes, and rivers. Unlike other cats, which tend to avoid water, tigers actively seek it out. During the extreme heat of the day, they often cool off in pools. Tigers are excellent swimmers and can swim up to 4 miles. This cat will also carry their dead prey across lakes.
Physical characteristics, taxonomy and evolution
The oldest remains of a tiger-like cat, called Panthera palaeosinensis, have been found in China and Java. This species lived about 2 million years ago, at the beginning of the Pleistocene, and was smaller than a modern tiger. The earliest fossils of true tigers are known from Java, and are between 1.6 and 1.8 million years old. Distinct fossils from the early and middle Pleistocene were also discovered in deposits from China, and Sumatra. A subspecies called the Trinil tiger (Panthera tigris trinilensis) lived about 1.2 million years ago and is known fossils found at Trinil in Java.[13]
Tigers first reached India and northern Asia in the late Pleistocene, reaching eastern Beringia (but not the American Continent), Japan, and Sakhalin. Fossils found in Japan indicate that the local tigers were, like the surviving island subspecies, smaller than the mainland forms. This may be due to the phenomenon in which body size is related to environmental space (see insular dwarfism), or perhaps the availability of prey. Until the Holocene, tigers also lived in Borneo, as well as on the island of Palawan in the Philippines.[14]
Physical characteristics
Siberian tigerTigers are among the most recognisable of all the cats. They typically have rusty-reddish to brown-rusty coats, a whitish medial and ventral area, a white "fringe" that surrounds the face, and stripes that vary from brown or gray to pure black. The form and density of stripes differs between subspecies (as well as the ground coloration of the fur; for instance, Siberian tigers are usually paler than other tiger subspecies), but most tigers have over 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 that 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 help tigers conceal themselves amongst the dappled shadows and long grass of their environment as they stalk their prey. The stripe pattern is found on a tiger's skin and if shaved, its distinctive camouflage pattern would be preserved.
Like other big cats, tigers have a white spot on the backs of their ears. These spots, called ocelli, serve a social function, by communicating the animal's mental state to conspecifics in the gloom of dense forest or in tall grass.
SkeletonTigers have the additional distinction of being the heaviest cats found in the wild.[15] They also have powerfully built legs and shoulders, with the result that they, like lions, have the ability to pull down prey substantially heavier than themselves. However, the subspecies differ markedly in size, tending to increase proportionally with latitude, as predicted by Bergmann's Rule. Thus, large male Siberian Tigers (Panthera tigris altaica) can reach a total length of 3.5 m "over curves" (3.3 m. "between pegs") and a weight of 306 kilograms,[16] which is considerably larger than the sizes reached by island-dwelling tigers such as the Sumatran, the smallest living subspecies with a body weight of only 75–140 kg.[16] 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 subspecies of tiger, with males weighing up to 1.7 times as much as the females.[17] In addition, male tigers have wider forepaw pads than females. This difference is often used by biologists in determining the gender of tigers when observing their tracks.[18] 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 lion's skull 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.[19]
Subspecies
A Bengal tigress with her cub.There are nine recent subspecies of tiger, three of which are extinct. Their historical range (severely diminished today) ran through Bangladesh, Siberia, Iran, Afghanistan, India, China, and southeast Asia, including some Indonesian islands. The surviving subspecies, in descending order of wild population, are:
The Bengal tiger or the Royal Bengal tiger (Panthera tigris tigris) is the most common subspecies of tiger and is found primarily in India and Bangladesh.[20] It lives in varied habitats: grasslands, subtropical and tropical rainforests, scrub forests, wet and dry deciduous forests, and mangroves. Males in the wild usually weigh 205 to 227 kg (450 to 500 lb), while the average female will weigh about 141 kg.[21] However, the northern Indian and the Nepalese Bengal tigers are somewhat bulkier than those found in the south of the Indian Subcontinent, with males averaging around 235 kilograms (520 lb).[21] While conservationists already believed the population to be below 2,000,[22] the most recent audit by the Indian Government's National Tiger Conservation Authority has estimated the number at just 1,411 wild tigers (1165–1657 allowing for statistical error), a drop of 60% in the past decade.[23] Since 1972, there has been a massive wildlife conservation project, known as Project Tiger, to protect the Bengal tiger. Despite increased efforts by Indian officials, poaching remains rampant and at least one Tiger Reserve (Sariska Tiger Reserve) has lost its entire tiger population to poaching.[24]
Indochinese tigerThe 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. Estimates of the Indochinese tiger population vary between 1,200 to 1,800, with only several hundred left in the wild. 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.
Malayan tigerThe 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,[25] part of the National Cancer Institute of the United States. Recent counts showed there are 600–800 tigers in the wild, making it the third largest tiger population, behind the Bengal tiger and the Indochinese tiger. The Malayan tiger is the smallest of the mainland tiger subspecies, and the second smallest living subspecies, with males averaging about 120 kg and females about 100 kg 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.
Sumatran tigerThe Sumatran Tiger (Panthera tigris sumatrae) is found only on the Indonesian island of Sumatra, and is critically endangered.[26] 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).[27] 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,[specify] if it does not go extinct.[28] 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.
Siberian tigerThe Siberian tiger (Panthera tigris altaica), also known as the Amur, Manchurian, Altaic, Korean or North China tiger, is confined to the Amur-Ussuri region of Primorsky Krai and Khabarovsk Krai in far eastern Siberia, where it is now protected. Considered the largest subspecies, it had a head and body length of 160–180 cm for females and 190–230+ cm for males, plus a tail of about 60–110 cm long (about 270–330 cm in total length) and an average weight of around 227 kilograms (500 lb) for males,[21] the Amur tiger is also noted for its thick coat, distinguished by a paler golden hue and fewer stripes. The heaviest wild Siberian tiger on record weighed in at 384 kg,[29] but according to Mazak these giants are not confirmed via reliable references.[16] Even so, a six-month old Siberian tiger can be as big as a fully grown leopard. The last two censuses (1996 and 2005) found 450–500 Amur tigers within their single, and more or less continuous, range making it one of the largest undivided tiger populations in the world. Genetic research in 2009 demonstrated that the Siberian tiger, and the western "Caspian tiger" (once thought to have been a separate subspecies that became extinct in the wild in the late 1950s[30][31]) are actually the same subspecies, since the separation of the two populations may have occurred as recently as the past century due to human intervention.[32]
South China tigerThe 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.[33][clarification needed] One of the smaller tiger subspecies, the length of the South China tiger ranges from 2.2–2.6 m (87–100 in) for XXXX 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.[34] In 2007 a farmer spotted a tiger and handed in photographs to the authorities as proof.[34][35] The photographs in question, however, were later exposed as fake, copied from a Chinese calendar and photoshopped, and the “sighting” turned into a massive scandal.[36][37][38]
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.
Extinct subspecies
A hunted down Balinese tigerThe Bali Tiger (Panthera tigris balica) was limited to the island of Bali. They were the smallest of all tiger subspecies, with a weight of 90–100 kg in males and 65–80 kg in females.[16] These tigers were hunted to extinction—the last Balinese tiger is thought to have been killed at Sumbar Kima, West Bali on 27 September 1937; this was an adult female. No Balinese tiger was ever held in captivity. The tiger still plays an important role in Balinese Hinduism.
A photograph of a Javan tiger.The Javan tiger (Panthera tigris sondaica) was limited to the Indonesian island of Java. It now seems likely that this subspecies became extinct in the 1980s, as a result of hunting and habitat destruction, but the extinction of this subspecies was extremely probable from the 1950s onwards (when it is thought that fewer than 25 tigers remained in the wild). The last confirmed specimen was sighted in 1979, but there were a few reported sightings during the 1990s.[39][40] With a weight of 100–141 kg for males and 75–115 kg for females, the Javan tiger was one of the smaller subspecies, approximately the same size as the Sumatran tiger.[citation needed]
A captive Caspian Tiger, Berlin Zoo 1899Caspian Tiger (formerly Panthera tigris virgata), also known as the Persian tiger or Turanian tiger was the westernmost population of Siberian tiger, found in Iran, Iraq, Afghanistan, Turkey, Mongolia, Kazakhstan, the Caucasus, Tajikistan, Turkmenistan, and Uzbekistan until it apparently became extinct in the late 1950s, though there have been several alleged more recent sightings of the tiger.[31] Though originally thought to have been a distinct subspecies, genetic research in 2009 suggest that the animal was largely identical to the Siberian tiger.[32]
Hybrids
Further information: Panthera hybrid, Liger and Tiglon
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.[41] Lions have been known to breed with tigers (most often the Amur and Bengal subspecies) to create hybrids called ligers and tigons.[42] 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.[43] 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 XXXX 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.[43]
The less common tigon is a cross between the lioness and the male tiger.[44]
Colour variations
White tigers
Main article: White tiger
A pair of white Bengal tigers at the Singapore Zoo.There is a well-known mutation that produces the white tiger, technically known as chinchilla albinistic,[45] 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).[46][47] 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.[48] They can only occur when XXXX 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[49] (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.[46][50] 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 and pink noses.
Golden tabby tigers
Main article: Golden tabby
A rare golden tabby/strawberry tiger at the Buffalo Zoo.In addition, another recessive gene may create a very unusual "golden tabby" colour variation, sometimes known as "strawberry." Golden tabby tigers have light gold fur, pale legs and faint orange stripes. Their fur tends to be much thicker than normal.[51] There are extremely few golden tabby tigers in captivity, around 30 in all. Like white tigers, strawberry tigers are invariably at least part Bengal. Some golden tabby tigers, called heterozygous tigers, carry the white tiger gene, and when two such tigers are mated, can produce some stripeless white offspring. XXXX white and golden tabby tigers tend to be larger than average Bengal tigers.
Other colour variations
There are also unconfirmed reports of a "blue" or slate-coloured tiger, the Maltese Tiger, and largely or totally black tigers, and these are assumed, if real, to be intermittent mutations rather than distinct species.[45]
Biology and behaviour
Territorial behaviour
Tigers are essentially solitary and territorial animals. 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 square kilometres while the territories of males are much larger, covering 60–100 km2. The ranges of males tend to overlap those of several females.
Tigers for the most part are solitary animals.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, XXXX male and female tigers have been documented sharing kills. For instance, 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 Valmik Thapar and Fateh Singh Rathore in Ranthambhore:[52]
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.[53]
Two male Bengal tiger siblings play with each other in the Pilibhit Tiger Reserve, India.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.[54] 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.[53] 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 actually a relatively rare occurrence.[53][55]
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 XXXX 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 found faulty[56] and 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
Tiger dentition(above), compared with that of an Asian black bear (below). The large canines are used to make the killing bite, but they tear meat when feeding using the carnassial teeth.In the wild, tigers mostly feed on larger and medium sized animals. Sambar, gaur, chital, barasingha, wild boar, nilgai and XXXX water buffalo and domestic buffalo are the tiger's favoured prey in India. Sometimes, they also prey on leopards, pythons, sloth bears and crocodiles. In Siberia the main prey species are manchurian wapiti, wild boar, sika deer, moose, roe deer, and musk deer. In Sumatra Sambar, muntjac, wild boar, and malayan tapir are preyed on. In the former Caspian tiger's range, prey included saiga antelope, camels, caucasian wisent, yak, and wild horses. Like many predators, they are opportunistic and will eat much smaller prey, such as monkeys, peafowls, hares, and fish.
Adult elephants are too large to serve as common prey, but conflicts between tigers and elephants do sometimes take place. A case where a tiger killed an adult Indian Rhinoceros has been observed.[57] Young elephant and rhino calves are occasionally taken. Tigers also sometimes prey on domestic animals such as dogs, cows, horses, and donkeys. These individuals are termed cattle-lifters or cattle-killers in contrast to typical game-killers.[58]
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.[59] Tigers will occasionally eat vegetation for dietary fiber, the fruit of the Slow Match Tree being favoured.[58]
Tigers' extremely strong jaws and sharp teeth make them superb predators.Tigers usually hunt at night.[60] 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 large prey off balance. 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. Tigers have great leaping ability; horizontal leaps of up to 10 metres have been reported, although leaps of around half this amount are more typical. However, only one in twenty hunts ends in a successful kill.[60]
When hunting large prey, tigers prefer to bite the throat and use their forelimbs to hold onto the prey, bringing it to the ground. The tiger remains latched onto the neck until its prey dies of strangulation.[61] By this method, gaurs and water buffalos weighing over a ton have been killed by tigers weighing about a sixth as much.[62] With small prey, the tiger bites the nape, often breaking the spinal cord, piercing the windpipe, or severing the jugular vein or common carotid artery.[63] 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,[58] and break the backs of sloth bears.[64]
During the 1980s, a tiger named "Genghis" in Ranthambhore National Park was observed frequently hunting prey through deep lake water,[65] 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.
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