A long-standing friend of mine, noted cat geneticist Roy Robinson , had asked me to collect data on this colour variety which I was in the process of doing when , sadly, Roy died.
I first became aware of this colour variety in 1984 or 1985 when on the television news a Keeper from Columus Zoo, Ohio appeared with an armful of tiger cubs: two browns, a white, and in the middle one of these gingery ones. I thought at the time it was one of the most dramatic visual images I had seen in Zoos.
White Tigers in the wild have a long history, longer perhaps than many people realise. On the walls of entrance passageways to ancient Chinese Tombs, 3,000 or more years of age, are painted the symbols of the four elemental forces forces of nature - represented amongst other things by a Green Dragon, and a White Tiger !
The White Tiger, could, like the Green Dragon have remained solely as an image, were it not for a number of features:
- Firstly, China was and still is, well within the natural range of tigers.
- Secondly, just like the White Buffalo (Bison) it is inevitable that white varieties will occur from time to time.
Just how often these occur is debatable. In the case of the White Buffalo (or Elephant, for that matter), each instance over the past 2,000 years has probably been the result of a genuine first mutation.
In the case of the White Tiger, whilst this might well also have been the case, and probably on some occasions was, it need not necessarily have been so.
We now know that the mutation is inherited as an autosomal recessive. Thus it is capable of being passed down, without being visible, from generation to generation until a chance encounter with another tiger, also carrying this recessive factor, results in a cub or cubs being born, which visually display the White colouration. Obviously, the possibility of this happening is far greater in those areas where the population is significantly " in-bred ". This does happen naturally, in nature, as Cheetahs have shown, where two or more " genetic bottlenecks " have occurred in the last 10,000 or so years. Where for some reason, a population of tigers is relatively isolated, then it is likely that they will become in-bred.
Nowadays, many populations of tigers are extremely dispersed and isolated as agriculture and population growth forces their numbers down and confines them to reserves. In recent centuries, whilst this process had already begun, geographical isolation of a remote valley or other restriction imposed geographical features would have had the same effect.
Some districts in India, became quite celebrated for producing White Tigers with some regularity. So it was that the Maharaja of Rewa issued an order that the next White Tiger to be produced was to be captured alive and brought to him. The story is well known, and reproduced elsewhere on the WWW. However, a cub, Mohan duly appeared, was captured, and on maturity was mated to a normal brown female. One of the brown cubs (the normal brown colour being the dominant colour) was mated back to her father Mohan . The theoretical expectation (over 100 matings) was that an average of 50 of the cubs would turn out to be white. In the first litter four white cubs were produced!
From these animals the studbook registered (because they are pure-bred Indian Tigers) White Tiger strain is descended.
As a school-boy I dragged my parents and brothers over 100 miles to see two of these White Tigers which had been purchased by Bristol Zoo (I still have the post-card souvenir!)
"At the time, we didn't have two farthings to rub together " said present Director Geoffrey Greed " but those two tigers, followed by the Okapis re-built the fortunes of Bristol Zoo."
By 1973, when they still hadn't bred successfully I discussed with Reg Greed, Geoffrey's father ( by then I was Director of Glasgow Zoo ) the advisability of introducing some fresh blood by means of an outcross.
"You could always let us have some of the brown cubs, they would all be browns, but carrying white recessively".
A few years later a brown male from Edinburgh Zoo was tried with a white female, I'd have attempted it the other way round, with a white male to a number of brown females. What did it matter if lots of brown splits were produced? Anyway, the pairing never reared any cubs. In retrospect, this was fortunate as the Edinburgh male was a " non-generic " zoo tiger and these whites were pure-bred studbook, Indians from a known point of origin in India.
In the late 1980s, Longleat Safari Park imported a male While Tiger of the American non-generic strain (the National Zoo in Washington has individuals of the original Mohan strain). These non-generic tigers are despised by zoo conservationists, and endangered species demographics because the contain Siberian Tiger genes. They are often regarded as a " waste of space ", justified if at all, by their undoubted visitor appeal.
As the King-pin amongst a group of 6 to 9 females, this male made an arresting sight in Longleat Safari Park, fully justifying the decision to purchase him.
Many cubs were born in the succeeding years, some of which exhibited even more variation.The first whites were marked just like the browns except the stripes were chocolate and their eyes were blue. When these were bred together in later generations, as might be predicted, maximum variation started to evidence itself.
In 1994, I saw at Longleat a litter bred from a brown female carrying White genes mated to a " Ginger Tom " type male. The litter contained two normally marked browns, another " Ginger Tom ", and a White with absolutely no markings except a few rings around its tail (this animal is now in Japan).
Butu is from this pairing, although he was hand-reared. He is one of 7 or 8 examples bred by Longleat (and there are others in the USA, e.g. Columbus Zoo). They all breed genetically like White Tigers
Interestingly, the old natural history books and hunters folk-lore suggests that White Tigers in the wild are not maladapted and are perfectly capable of living a full life-span. Both they and their ungulate prey are seen in tones of grey, although the warning calls of birds and monkeys are emitted by creatures with acute colour vision..
In our one acre sloping, naturalistic enclosure, thickly planted with trees (incidentally , the only tiger enclosure to be so in UK Zoos) I have seen how White Tigers white tigers with chocolate stripes can disappear amongst the dappled shadows, with as much facility as its normal coloured relatives,
Only man singles such animals out to be shot or captured as trophies. Centuries ago individual animals probably lived their full allotted span, and by reproducing, distributed their recessive genetic make-up, to remain non-visual possibly for hundreds of years, until encounters with another heterozygous animal caused them to reappear visually as a White cub again.
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