White tiger
White tigers are tigers with pink noses and white to cream colored fur with black, grey or chocolate-colored stripes; their eyes are usually blue, but may be green or amber. There are around 600 white tigers in the world. Because this coloration is so striking, white tigers have become popular attractions in zoos and entertainment that showcases exotic animals; the magicians Siegfried and Roy are famous for using several trained white tigers in their shows. Contrary to popular belief, white tigers are not an endangered species in their own right, but are a selectively bred mutant form of normal orange tigers.
The color is caused by a recessive gene. The gene for white coloration is usually associated with Bengal tigers, although the vast majority of Bengal tigers have normal, orange-and-black coloration. White tigers have occurred in the Amur or Siberian tiger subspecies. Two registered pure-bred Amur brothers bred at Como Zoo, Minnesota may have carried the white gene (their most famous descendent being Tony). Their wild-caught parents were pure Amur tigers. These white Amur tigers have been interbred with white Bengal tigers as well as leaving pure-bred Amur offspring. As well as white generic tigers and white Bengal tigers, there are purebred white Amur tigers in existence. Most white tigers bred in captivity are generic tigers i.e. hybrids of two subspecies - most commonly, half Bengal and half Siberian.
Contrary to popular belief, white tigers are not albino; true albino tigers would have no stripes. Since "white tigers" are not actually pure white, they are sometimes called chinchilla tigers in order to avoid confusion. Other names are ice tigers referring to their frosty appearance and not to their habitat. There is no evidence of true albinism in modern tigers; to date, all so-called "albino tigers" have so far been chinchilla tigers with unusually pale stripes. Part of the confusion is due to the mis-identification of the chinchilla gene as an allele of the albino series (publications prior to the 1980s refer to it as an albino gene).
The only case of true albino tigers was recorded in 1922 at Mica Camp, Tisri in the Indian state of Cooch Behar when two pink-eyed albino young tigers were shot along with their mother. Lydekker (1907) doubted the existence of albino tigers, but old records of Cooch Behar describe a tawny tigress who was shot along with 2 coloured and 2 sickly-looking white cubs (young adult tigers) that had extended necks and pink eyes. In "Animal kingdom", the 18th century French naturalist Baron Georges Cuvier described a white tigress whose stripes were visible only at certain angles of reflection.
A pure white tiger was described in the 1800s and showing ghost stripes: "A wholly white tiger, with the stripe-pattern visible only under reflected light, like the pattern of a white tabby cat, was exhibited in the Exeter Change Menagerie in 1820 and described by Hamilton Smith".
White tigers have always been extremely rare in the wild. Since Mohan's capture (see below), there have been no further confirmed sightings, although zoologists believe that the gene may still be found in certain wild Bengal tiger populations.
White Tigers in Captivity
Most white tigers currently in captivity can trace ancestry to a single individual - a male named Mohan, captured in India in 1951. Although Mohan was not the first white tiger in captivity, he was the first to successfully breed in captivity. Mohan was bred to a wild-caught orange tigress named Begum, but they produced only orange cubs because Begum did not carry the white gene. Mohan was then repeatedly bred to his daughter Radha. Radha's offspring included Mohini (Enchantress). Mohan died in 1969, aged almost 20. He was the last recorded wild-caught white tiger and the first Bengal tiger to be registered in the International Tiger Studbook at Liepzig Zoo.
Because of their novel appearance, Mohan's descendents were traded to zoos around the world. Mohini went to Washington in 1960 to found a line of white tigers there. With no further white tigers being exported from India, Mohini was mated to Sampson, her orange uncle and also to her half-brother who carried the white gene. Mohini became the matriarch of Washington's white tigers and the ancestor of the majority of the white tigers outside of India.
Another genetically important white tiger is Tony (born 1971), who is the progenitor of almost all white tigers in North America. Tony is the offspring of a brother/sister pair of Amur-Bengal hybrid tigers called Raja and Sheba II owned by the Shrine Circus. Tony was bred to Mohini's orange daughter Kesari, founding an extensive dynasty of white tigers in the USA. The names of Mohan, Mohini and Tony often appear several times in the the pedigrees of white tigers alive today.
In 1980, a white tiger cub was bred at the Racine Zoo in Wisconsin from a father/daughter mating. The mother later produced more white offspring, but it is not known how she or her father came to carry the white gene.
An unrelated strain of white tigers arose at Nandankanan Biological Park, Orissa, India in the 1980s from a tiger called Deepak who was bred to his own daughter Ganga. Deepak must have inherited the white gene from his parents and passed it on to his daughter. Deepak was not related to Mohan or to Mohan's descendants.
Inbreeding Depression
Because the gene pool is so small, many white tigers suffer from health problems due to inbreeding. For this reason, responsible zoos refuse to breed two white tigers together. However, two white parents are the only way to ensure white cubs; if a white tiger mates with a partner that is heterozygous for the gene, only one in four of the offspring will be white. Thus, due to the high demand for white tigers, less scrupulous breeders still breed white tigers together. Some animal rights activists have called for a halt to the breeding of white tigers altogether.
Outside of India, highly inbred white tigers are prone to cross eyes (strabismus) due to incorrectly routed visual pathways in the brain), star-gazing and postural problems, a weakened immune system and poor tolerance of anaesthesia, possibly due to inability to synthesize the tyrosinase enzyme. Strabismus is associated with white tigers of Bengal/Amur ancestry. Only one pure Bengal white tiger was reported to be cross eyed, this being Mohini's daughter Rewati.
White tigers may also be prone to Chediak-Higashi Syndrome which causes bluish lightening of the fur colour and is associated with crossed eyes. Other genetic problems include shortened tendons of the forelegs, clubbed feet, central retinal degeneration, abnormal kidneys, arched or crooked backbone and twisted neck. Reduced fertility and miscarriages were noted by Sankhala and weere attributed to inbreeding depression. Some of the white tigers born to North American lines have bulldog faces with a snub nose, jutting jaw, domed head and wide-set eyes with an indentation between the eyes. However, some of these traits have also been linked to poor diet.
White tigers tend to be larger than their orange (normal) relatives. This has led to suggestions that the gene promotes larger size and that the disadvantageous white colour in homozygoutes is a side effect. The Zoo Outreach Organization in Tamil Nadu, India maintains a white tiger studbook compiled by AK Roychoudhury of the Bose Institute in Calcutta.
Historical records
White tigers have been recorded outside of the Indian state of Rewa and as far afield as China and Korea and from Nepal, Burma, the Malay Peninsula, Sumatra, and Java. Historically, white tigers have been reported in northern China, in the geographic range of the Amur tiger (previously called the Manchurian/North China tiger and the Siberian tiger) and in the Indo-Chinese, Sumatran and Javan subspecies. White tigers have not been reported amongst the South China, Caspian or Bali tigers.
White tigers form part of tradition in some regions. In China the white tiger was revered as the god of the West, Byakko. The white tiger is represented on the South Korean flag in the Yin and Yang emblem, the white tiger as evil opposite the green dragon for good. According to Indian superstition, the slayer of a white tiger would die within a year and the white tiger was regarded as the incarnation of a Hindu god. Sumatran and Javan royalty claimed descent from white tigers, and white tigers were regarded as the reincarnations of royalty.
White tigers with dark brown or reddish-black stripes were recorded in the wild during the Mughal Period from 1556 - 1605 AD. A painting from 1590 of Akbar hunting tigers near Gwalior depicts 4 tigers, 2 of which appear white. As many as 17 instances of white tigers were recorded in India between 1907 and 1933 in several separate locations: Orissa, Bilaspur, Sohagpur and Rewa.
One of the earliest records of white tigers is of one displayed in London in 1820 and described by Rev J G Woods as "a creamy white, with the ordinary tigerine stripes so faintly marked that they were only visible in certain lights". White tigers were routinely shot between 1892 and 1922 in places such as Orissa, Upper Assam, Bilaspur, Cooch Behar and Poona. Pollock (1900) reported white tigers from Burma and the Jynteah hills of Meghalaya, Between the 1920s and 1930s fifteen white tigers were killed in the Bihar region and more were shot in other regions. Some of the trophies exhibited in Calcutta Museum. In 1922, two pure white young adult tigers with pink eyes were shot in Cooch Behar (north-east India). At Mica Camp, Tisri in Behar. On 22 January 1939, the Prime Minister of Nepal shot a white tiger at Barda camp in Terai Nepal. In 1951, a normal coloured tigress and cubs were shot, but her white cub was captured alive some days later. This cub "Mohan" ("Enchanter") is ancestral to most modern white tigers. The last observed wild white tiger was shot in 1958 and the mutation is considered extinct in the wild. The slaughter of hundreds of orange tigers evidently killed the carriers of the mutant gene.hey was up