Why White Tigers ?

White Tigers … beautiful … majestic …  powerful.

Yet some people are calling them unnatural –  “mutant freaks” – and claiming that breeding them is animal cruelty.

Oh no ! Could this be true ?  Short answer – No, it is not true. 

I have been on an odyssey through science and history to discover the truth about white tigers, and to find out why there is so much confusion and downright misinformation being spread about them.

It has been time-consuming, and sometimes frustrating – but ultimately rewarding. It’s time to share the knowledge gained so that more people can make an informed opinion about these beautiful and endangered big cats – before it is too late.

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White Tigers that Turn Black

White Tigers that Turn Black

Pseudo-melanistic, or “black” tigers: – where did they come from, and why are they suddenly popping up now in the captive white tiger population ?

“Black” Cubs Born in Captivity

Sembian with his mother Anu, at Arignar Anna Zoo, Vandalur.
Photo by Fightingfalcon2005 (CC BY-SA 3.0 )

In June 2010, a white tiger pair (Anu and Bhishmar) at the Arignar Anna Zoo in Vandalur, India, had their 2nd litter of 3 white tiger cubs. One of these cubs was different – his white coat appeared to be turning black! As the cub, Sembian, matured, it became apparent that the blackness was due to an expansion of the normal black stripes, termed “abundism” or more popularly called “pseudo-melanism”. Sembian’s coat had a white background with an over-abundance of blackness – his black stripes were so wide they ran together in places. [1]

Pseudo-melanistic tigers at Nandankanan zoo.
Photo by PALLABI SEN (Own work) (CC BY-SA 4.0)

In July 2014, it happened again, this time at the Nandankanan Zoo in Orissa, India, and this time the litter of 4 was a mixture of white and orange cubs born to Sneha and Manish, a white mother and orange father. Two cubs, 1 white and 1 orange, had the overabundance of black stripes . In May 2016 another pair at the zoo – Renuka and Samrat – had one pseudo-melanistic cub (stillborn). In August 2016 the first pair had another litter of 3 cubs – again, one cub was pseudo-melanistic. [2]

At first, the “black” cubs were thought to be “accidents” of nature, or “mutants” –  but after the 2016 litters the zoo realised they were dealing with normal genetic inheritance.

The Theory

Pseudo-Melanistic white tiger at Nandkanan Zoo.

Pseudo-melanism in tigers appears to be caused by a recessive gene – similar to the white gene, but separate from it as it can affect both white and orange tigers. This would mean that a “normal” orange or white tiger can carry the melanistic gene in a hidden state, as it is masked by the dominant allele.

So assuming it is an inherited trait, a trace of the pseudo-melanistic tigers’ pedigree should give us a clue where it came from. This leads back to 5 wild-born ancestors that all the melanistic cubs have in common: Mohan and Begum of the Rewa line, and Pradeep, Sikha and Rani of the Orissa line. [3] It is highly unlikely that the gene came from the Rewa tigers, as it should have shown up earlier during the inbreeding that occurred in the first few generations of that line. That leaves the 3 from the Orissa line, and a glance at the origin of these 3 tigers shows an obvious candidate : Rani.

Rani, an orange tigress, and one of the founders of the Orissa line of white tigers, was found wild in the Similipal forests in 1967, as a little 7wk old cub. [4]

Location of Similipal Forests.
Source: Google Maps

The Similipal Tiger Reserve had for many years been rumoured to harbour “black” tigers, – rumours that were widely dismissed as myth until 1993 when proof was obtained (the skin of a slain tiger). [5] Since then these pseudo-melanistic orange tigers have been photographed by camera traps in the reserve, and it was estimated that there were 3 of them living there in 2014. The Similipal tiger population is threatened, with only an estimated 26 tigers left there in 2016. [6]

Back in 1975, in the Nandankanan zoo, Rani the Similipal tigress mated with Deepak, an orange male who was later found to carry the white gene. Apparently Rani passed the melanistic trait on to her daughter Ganga (also a white gene carrier), who then passed it on to one or more of her many cubs.

Throughout the next 3 or 4 generations, the recessive melanistic gene gradually spread unnoticed throughout the Nandankanan tiger population, until finally 2 melanistic gene carriers were paired together.

Possible path of pseudo-melanism inherited from tigress Rani. Note: Abbreviated chart.

Meanwhile, in 1999, Laxman, a white male tiger from the Orissa line, was sent to the National Zoological Park in Delhi to breed with their Rewa line white tigers. Laxman was also descended from Rani, and it is possible that he carried the melanistic gene and passed it to some of his descendants, including Anu and Bhishmar, who became the parents of the blackened Sembian. [note i]

There have been too few melanistic births to be certain which of Ganga’s offspring carried the trait, as it is not likely she passed it to all her cubs. A study of the full birth charts shows the most likely option to be Debabrata plus either Pinaki or Jamuna.

This abbreviated chart above shows the possible line of inheritance. Please note that this chart does not show all the generations and tigers involved. For full (and complicated!) details please refer to the ancestry charts in White Tigers Today..

Is it Caused by Inbreeding?

Inbreeding is one way that a recessive trait can show up. However, the expression of a recessive trait does not automatically signify inbreeding, but simply that a trait has had time to be distributed throughout a population unnoticed (because it is masked by the dominant allele).

This late showing of a recessive trait that has been present in the captive population since 1967, illustrates how careful the zoos have been to avoid close inbreeding in the Orissa line of white tigers. [note ii] It has taken all this time for the gene(s) to spread throughout the population – the Nandankanan pseudo-melanistic cubs are 4 generations removed from any common ancestor, and SIX generations removed from the presumed origin, the tigress Rani.

Significance for White Tigers and Tigers in General

Occurrence of White Tigers in the Wild

This concept of a recessive trait spreading unnoticed throughout a population (see above)  is also important in understanding the occurrence of white tigers in the wild. They did not just pop up here and there spontaneously – 1 in 10,000 –  as often suggested, but the hidden white gene seems to have spread from NE India through to Central India, in time becoming so common in some areas that white tigers were born more frequently in these areas –  eg Rewa and Bihar. [7]

Captive Populations Preserving Genetic Diversity

As Rani’s daughter Ganga also carried the white gene (from her father Deepak), she was bred extensively and has many descendants in the captive population today. In the effort to preserve the white gene, the zoos have inadvertantly also preserved other tiger genetic diversity that is endangered in the wild. The pseudo-melanistic trait is a visible example of this, but there is likely much more variation thus preserved that we cannot see with the eye.

“Real” Tigers Come in Many Colours

Throughout history, hunters and naturalists have observed and recorded wild tigers in a startling array of coat colour variations – the common orange with black stripes; white with black stripes; white stripeless; orange stripeless; dark brown with black stripes; heavy black stripes; varying shades of pale to deep orange; black with black stripes; “blue” tigers. [8]

Today only the orange-with-black-stripes variety remains in the wild with any regularity, causing many people in the current generation to believe that they are the only “real” tigers, and that all others are mythical or man-made. The reality is that these beautiful orange-and-black tigers are merely the remnants of the once large and highly diversified tiger population that included many different coat variations.

Conclusion

“Black” tiger in Nandankanan Zoo.
Photo by Jitendraamishra (Own work) (CC BY-SA 4.0) 

The pseudo-melanistic trait arose naturally in the wild, where it apparently survives only in Similipal today. Fortuitously, one tigress from this area was taken into captivity 50 years ago and bred, thus preserving some of the unique genetic diversity of the tigers from that area.

It is highly likely that Rani, the little wild cub from Similipal,  carried the pseudo-melanistic trait and passed it on to her daughter Ganga, who passed it on to one or more of her own cubs.

As the Simlipal population is currently threatened, this is another instance of captive tigers (both white and orange) serving as a reservoir of genetic diversity that is endangered in the wild.

 

Notes

[i] Amongst Anu and Bhishmar’s 13 cubs there were no other reported melanistic cubs. This might indicate that there are other factors influencing or suppressing the trait. 

 [ii] There was only one father-daughter pairing, that of Deepak to Ganga. Offspring were then outcrossed to the unrelated Rewa line, and I have not found any further parent-child or sibling pairings at Nandankanan. In recent years they have also outcrossed to wild tigers, thus strengthening their gene pool further.

The initial breeding of Ganga to her father Deepak would not have produced pseudo-melanistic cubs as we assume that only Rani (not Deepak) carried the gene, which she then passed to her daughter Ganga.

Sources

[1] Times of India, August 30, 2010 – White tiger cub turns black in Chennai Zoo

– Plus many other news reports

[2]

[3] The White Tiger Dataset; and  Bengal Tiger Studbook Dec 2012

[4] Birth of White Tiger Cubs to Normal Coloured Tigers in Captivity, by CH G Mishra, L N Acharjyo, L N Choudhury in JBNHS vol 79 1982.

[5]

  • Born Black – The melanistic Tiger in India by L A K Singh. WWF India. Sept 1999.
  • “Black Tigers” – Reality or Myth by Dr L A K Singh, in WWF Tiger Update, v1 No 4, Oct 1996
  • Black on white or White on Black… by BC Prusty and LAK Singh, in Zoos’ Pring, v XII, No 1, Jan 1997
  • Black Tigers of Similipal Tiger Reserve, Orissa by G H Mishra, in Indian Forester, V122, No 10, Oct 1996.

[6]

[7]

[8]  Born Black – The melanistic Tiger in India by L A K Singh. WWF India. Sept 1999. (Plus many books/articles written by hunters and naturalists in the 19th and 20th centuries)

White Tigers Today – Are They Inbred ?

White Tigers Today – Are They Inbred ?

Ancestry charts indicate that today’s white tigers are genetically diverse and very far removed from the inbreeding of 50 years ago. The tigers have mixed ancestries, from numerous unrelated founder tigers, resulting from 5-6 generations of outcrossing. The proof is in the studbooks. Overall, white tigers today are not inbred and not descended from “only one tiger”.

This study is about the status of white Bengal tigers in India, but has parallels with populations in other countries.

Summary

  1. Condensed Ancestry Charts
    • Mohan-Begum chart, the Rewa line
    • Pradeep-Sikha chart, the Orissa line
  2. So where is all the inbreeding ?
  3. How much inbreeding = “inbred” ?
  4. Significance of outcrossing – adding new founders
    • Graph showing the gene pool increasing over time
  5. Genetic diversity of the founders
    • Map of geographic locations
  6. Are all descended from Mohan ?
  7. Conclusion
  8. A note about the accuracy of the charts
  9. Sources

Definition of Terms
hz = heterozygous for the white gene, ie an orange tiger that carries the white gene

IC = inbreeding coefficient

Outcrossing = mating with an unrelated Bengal tiger

 

1. Condensed Ancestry Charts

The International Bengal Tiger Studbook and the White Tiger Datset contain records of 100’s of tigers born since the 1950s but it is difficult to get a sense of the overall situation without spending many hours studying them. So below are 2 condensed ancestry charts, concerned only with the ancestry of living (or recently alive) white and hz tigers. They use color to show the breeding, outcrossing, and the multitude of different lines, at a glance:

  • Each color shading represents a different line of white/hz tigers with a different mix of founding ancestors – eg pale blue for the line descended from only Mohan and Begum;  light orange for Mohan/Begum/Tipu descendants; etc. Note that tigers of the same line (chart-color) are not identical, they each have a different mix of genes inherited from the various founders in their line.
  • A bright orange bar represents an unrelated outcross, resulting in a new line of tigers, shown by a new chart-color (or stripes). The outcross can be either with a new wild-born founder, or a cross between the Rewa and Orissa lines. Cubs of outcrossings have zero inbreeding.

The charts are read from left (1950s) to right (2016) and show tiger mating partners (in italics), and resulting cubs (in boxes) by generation (in columns). The cubs are grouped by parents, not by individual litter. Family lines that have died out, or that have only  possibly-hz descendants are omitted. For the most part, tigers on the left-hand half of the charts are deceased, those on the right still alive.

  • Left to right = 1950’s to 2016
  • LH side = deceased, RH side = alive
  • Chart-colors = different lines of tigers
  • Bright orange bar = unrelated outcross (IC=0)
  • Click charts to open in new window, click again to enlarge.

Mohan-Begum Chart – The Rewa Line

Rewa Line of Mohan and Begum – Ancestry of current white/hz tigers

The first chart starts from the Rewa line, tracing Mohan and Begum’s descendants.

Following the chart colors from left to right, it is easy to see that:

  • There are NONE of the original pure Rewa line (pale blue) left alive today ie tigers descended ONLY from Mohan and Begum (so clearly no tigers that got all of their genes from Mohan !)
  • There are numerous different lines of white/hz tigers with a kaleidoscope of different founders in their ancestry.
  • There was some inbreeding, but the early inbred lines were corrected by outcrossing to unrelated tigers – (orange bars on the chart).

 

Pradeep-Sikha Chart – The Orissa Line

WhiteTigerAncestryPSC

Orissa Line of Pradeep, Sikha, Rani – Ancestry of current white/hz tigers

The second chart starts from the Orissa line, following Pradeep, Sikha, and Rani’s descendants, and their crosses with the Rewa line. There is less early inbreeding than in the Rewa line, and there is a recent trend towards more outcrossing (eg Sara, Nandan, Jeevan, Cheri).

In the middle of the chart, where tigers of the same line have been paired, matings tend to be between distantly related tigers rather than siblings. For example, with a recent litter (Anini, Krishna, Snehashish, Subhransu) we have to go back 4 generations to find a common ancestor in the pedigree.

There does appear to be some sibling and mother-son inbreeding in recent times (eg Sunder-Tapsi, Sunder-Kamla), which is not good to see, but this involves a small number of zoos and does not affect the rest of the population (see below).

2. So where is all that inbreeding we were told about ?

There was indeed more inbreeding than is shown on these 2 charts, and it wasn’t restricted to white tigers. However, these charts show the ancestry of only the current population of white and hz. The full charts show more instances of inbred lines, and failed inbreeding attempts – but many of those inbred tigers of the past have no living descendants in the white tiger population today.

Past inbreeding of tigers that have no living descendants today has no effect on the current population.*

Inbreeding tends to be self-limiting – after 2-3 generations of continuous inbreeding, the inbred line dies out. (IC>.47). Not a good strategy !

This is likely to happen with the few current cases of inbreeding mentioned above – if not rescued by outcrossing, they will likely die out – hopefully these few zoos will change their practices in line with the majority, the aim should be to breed healthy tigers and avoid inbreeding.

* This is not saying that the inbreeding was OK – it is not necessary and not recommended. However, this article is not about judging the past, it is looking at the present and the status of white tigers today.

3. How much inbreeding = “inbred” ?

Inbreeding is a matter of degree, measured by the Inbreeding Coefficient (IC) on a scale of 0 to 1. For example:

  • IC of 0 = zero inbreeding.
  • IC of 0.25 = 25% inbreeding (eg from a full siblings mating).
  • IC of 0.01 = 1% inbreeding.

At what point do we say an animal, or population, is “inbred” ? If we use the IC>0 criteria, then we’d probably have to say that most white tigers today are inbred BUT we would also then have to say that most captive tigers are inbred – and quite possibly most wild tigers also. (Inbreeding has been observed in wild tigers – and lions – and increases with population fragmentation).

The charts show that there are white/hz tigers with zero inbreeding, and more with a very low level (as their parents were only distantly related).

“Inbred” is popularly understood to mean severely inbred, suffering or close to inbreeding depression. White tigers were at this point 40-50 years ago. Today they are not – they are very far from it.

4. Significance of Outcrossing – Adding new Founders

White tigers are not considered to be a separate subspecies. This puts them in a very strong position: it is not necessary to breed one white tiger to another white tiger. They can be bred to unrelated orange Bengal tigers, adding new founders into the population, and producing hz cubs.

We are 5 to 6 generations onwards from the Rewa line of Mohan-Begum, and the number of founders has increased dramatically from 2 to 19. Each new founder brings his or her unique set of genes into the pool, increasing the genetic variety available to the next generation. The process is ongoing.

  • Each tiger cub gets half of its genes from its mother, and half from its father. When mother and father are unrelated, as in an out-cross, there is zero probability of any of the genes being “identical by descent”, and therefore there is zero inbreeding. This is how inbreeding is corrected.

The graph shows the founders joining the India white tiger gene pool (in blue), 24 in all but 5 have left. (They join the pool when their first white/hz descendant is born, and leave it when their last known white/hz descendant died.)

Look at how that gene pool increased in size!

But numbers are not everything – a small number of founders can hold a large genetic variety if they come from a very diverse population or far-flung locations. Conversely, a large number of founders might have little variation if they all came from one small inbred population.

5. Genetic Diversity of the Founders

WhiteTigerFounderMapThe map shows approximate locations for the capture of the wild-born founders, where known. They are from a wide range of geographic locations and therefore very likely to be a genetically diverse bunch. Add to this that they were collected over a 60 year time period, making it even more likely that they represent very good diversity.

6. Are all descended from Mohan ?

All white tigers in India today are descended from Mohan – AND from Begum, Pradeep, Sikha, and Rani. All 5 of these founder tigers feature in the ancestry of most white/hz tigers. The other 14 founders also feature but in lesser proportions. This is not uncommon:

“In an ideal situation, each founder would be equally represented in the living SSP population. This is seldom the case—typically, a large proportion of the animals have descended from a few prolific founders who have many more living descendants than other founders and are thus more fully represented in the population’s gene pool. ”

from Management and Conservation of Captive Tigers – Ch 8 Intro to a Species Survival Plan (SSP) R. Tilson, K. Traylor-Holzer and G. Brady

After all the outcrossing and generations since Mohan, it is even possible that there are white tigers today that have few of Mohan’s original genes, even though he is an ancestor. Even the white gene itself could have come from the Orissa line (Sikha).

Having Mohan as an ancestor is not a bad thing at all though – he was a fine, big long-lived white tiger (19 years), a fitting patriarch. Begum, Pradeep, Sikha and Rani also lived to good old ages of 16 or 17.

7. Conclusion

Are today’s white tigers “inbred”?

Their ancestry indicates that they are genetically diverse. 5 to 6 generations of outcrossing has increased the gene-pool to that of 19 founders from widely-separated geographic locations, resulting in a mixture of lines and ancestors. Much of the past inbreeding has no effect on the current population (as there are no descendants). While some individual tigers may be inbred today, inbreeding is now the exception not the norm. Taking all this into account, it is reasonable to state that white tigers today are not inbred.

The breeding history is not perfect, and more work would be needed to make the population “text book perfect” – but it is impressive how well the Indian zoos have done over all with the white tiger breeding pool.

8. A note about the accuracy of the charts

The ancestry of some tigers is not clear, and if it looks like there could have been inbreeding, I assume the worst, ie that there was inbreeding. My apologies to the zoos concerned if it is incorrect. I will gladly correct any errors when informed.

The charts are a work in progress and may be updated from time to time.

9. Sources

Studbook of White Tigers in Indian Zoos in ZOO ZEN Vol IV Issue XI June 1989.

International Studbook of Bengal Tigers 2012

Management and Conservation of Captive Tigers – Ch 8 Intro to a Species Survival Plan (SSP) R. Tilson, K. Traylor-Holzer and G. Brady

The White Tiger Dataset

Inbreeding in White Tigers – A K Roychoudhury and K S Sankhala. Proc. Indian Acad. Sci Vol 88B, Part 1, Number 5, Oct 1979.

Genetic Status of White Tigers at Nandankanan Biological park, Orissa – A K Roychoudhury and L N Acharjyo. in JBNHS V.79 1982.

 

 

White Tiger Cub Mortality and Longevity

White Tiger Cub Mortality and Longevity

WhiteTigerCubs

Analysis of the breeding records of approx 1700 Bengal tigers in Indian zoos has shown that white tigers have the same cub mortality and longevity as orange tigers.

 

There are some “statistics” floating around about white tigers that I have not seen backed up with any proof – such as the mythical 80% cub mortality, and a belief that white tigers die younger than orange. The average age for orange tigers in captivity is usually quoted as 16 years, while white tigers were thought to live to only 12 or 14 years on average.

I always want proof for any statements made, so I assembled a dataset of captive Bengal tiger breeding in Indian zoos from 1950’s to 2015, and analyzed it to find out what truth (or not) there was in these figures, and to see if the changes in breeding practices over the decades had had any effect.

I found cub mortality rate to be practically the same for white, orange, and heterozygous tigers, approx 35%, and the average age to be 12-13 years for all captive-born tigers.

As heterozygous orange tigers are the result of the white tiger breeding efforts, I separated known-heterozygous tigers into their own group (Hz) – otherwise they may have skewed the results for the orange tigers.

Details of the dataset, what it includes, and how it was built can be found here: The White Tiger Dataset  –  and tables of the results by decade are at the end of this article.

 

Cub Mortality

Cub mortality was calculated as the number of cubs who died at less than 1 year of age, divided by the total number of cubs born – per decade of breeding, and for the total period.

The average across the entire period, for each of the 3 groups, was practically the same:

  • White tigers:   36%
  • Hz tigers:        37.5%
  • Orange tigers: 34%

These figures are also comparable to the AZA-quoted rate for captive tigers in USA, 35%:

“Historically, the neonatal mortality rate for captive tiger cubs within the first year was about 40%; it has improved to about 35% (data from the AZA Tiger SSP)”

[Management and Conservation of Captive Tigers, M Bush et al]

Cub mortality can be caused by different things – first-time mothers sometimes neglect their litter, or cause death by accidental rough handling. Stressful conditions can cause a mother to reject her young, and differences between zoos may have an impact. Lack of appropriate nutrition during pregnancy can result in unhealthy cubs. Disease can strike down even healthy cubs. Inbreeding depression results in high (or total) cub mortality.

This analysis grouped all cub deaths together regardless of cause, but for white tiger breeding, the probability of inbreeding affecting cub mortality was of special interest.

The graph shows cub mortality rates per decade of breeding – and it reveals an interesting trend. While the rate for orange tigers remained relatively constant, the White and Hz rates peaked in the 1970’s, dropped sharply in the 1980s, then continued their downward trend to the “normal” level in the 1990’s.

This matches the historical evidence that a small period of intensive inbreeding was followed by improved breeding practices and the resulting healthier population.

CubMortalityGraph

Cub Mortality Rates of Captive-born Tigers in Indian Zoos 1950’s to 2015

1970’s: Short Period of Intensive Inbreeding

During the 1970s, all white tigers born in India were descended from only 2 wild-caught founders – Mohan and Begum. The increasing level of inbreeding resulted in inbreeding depression, as shown by the high cub mortality. This was duly noted back then, and the practice ceased by the 1980’s.

1980’s: A New Line of White and More Outcrossing

During the 1980’s, 2 more pivotal changes occurred: – the discovery of a new line of white tigers, the Orissa line, and the introduction of new orange founders into the white tiger breeding pool. During this decade, the number of founders jumped from 2 up to 10 for white tigers, and up to 14 for Hz tigers.

Continuing through the 1990’s, the number of zoos breeding white tigers increased, outcrossing continued, and the cub mortality rate dropped further, down to the “normal” level for orange tigers.

Longevity

The average age (at death) was calculated for adult tigers that reached reproductive maturity, 4 years of age (ie any tigers dying at less than 4 years were excluded). The average age for each of the groups was practically the same:

  • White tigers:   13.2 years
  • Hz tigers:         13.3 years
  • Orange tigers: 12.2 years
  • Wild-caught:   14.3 years

The tables at the end of the article show the age groups per decade of birth for each color type.

The greatest age recorded for a captive-born tiger was 24 years – 1 white and 1 orange tiger reached this age.

The results for wild-born tigers kept in captivity are shown for comparison. Wild-caught tigers appeared to reach a higher average age, and this age seemed to decrease from 17 in the 1950’s down to 14 BUT there is more uncertainty with the wild-born figures because:

  • The birth date of wild-caught tigers is an estimate, and accuracy may have changed over the decades.
  • The wild tigers were captured from a pool that already had the weaker members weeded out, so the survivors do not represent the full spectrum of ages etc.
  • Capture decisions have changed over time, wild tigers are no longer captured at will, but only the problem or rescued tigers are now brought into captivity.

 

Conclusion

White tigers in Indian zoos have the same cub mortality rate and longevity as orange tigers, ie approx 35% and 12-13 years.

There is no indication that the average cub mortality rate is or has ever been 80%.

The cub mortality rate of both white and heterozygous tigers has improved over time, matching the changes in breeding practices.

 

Data Tables

The figures quoted should be taken as indications only, for comparison, not as absolute values. Information on the dataset used can be found here:  The White Tiger Dataset

The tables show the births by decade for white tigers, heterozygous, orange, and wild-caught tigers kept in captivity. The number of tigers that are known to be still alive (at 2015) is shown, then the number of tigers for which no death date is recorded are in the “unk” unknown column (many of these are likely still alive). The % of tigers with unknown death date is in the “A+U” column.

The tigers with known death date are then grouped by age at death. The <1 year group represents the cub mortality group.

The age group %’s are calculated on the total number born. Note that meaningful data is not available for the higher ages from 2000 onward as many tigers born since then are still alive. For these, the total is given to 1999 instead of to 2015.

The final column gives the average age reached by adult tigers. Tigers less than reproductive age (4 years) were excluded from this calculation.

Tigers with unknown date of death (ie still alive or unknown) were also excluded – with the exception of 7 records from 1990-99 of aged tigers that were still alive as at 2015. They were included in the calculations at their current ages, being: Orange = 15 16 18 18 20 White=15 18

Table-ww-ow

Click to enlarge

table-oo

Click to enlarge

More Snow White Tigers in NE India c1800

More Snow White Tigers in NE India c1800

The natives of this district reckon 4 kinds of tiger (Vagh). 1st, Babbra, which is white, has very long hair about the head, and is the largest of all. It is very rare, nor have I met with anyone that has seen it, but I heard that one was killed by Digvijay Raja of Bhewopar some time before the English took possession, and the animal is said to be occasionally seen by the cowkeepers. From the circumstances of the long hair about the head, and of the animal having no spots, I should have imagined that it was the lion; but the people all say that the colour is pure white. It neither attacks  man nor domestic animals. The animal killed in Dinajpoor, and of which the skin was sent by the Marquis Wellesley to Sir Joseph Banks, was probably of this species. 2nd Nongiyachhor or the royal tiger, which lives chiefly among reeds, or in the thickets….

This extract is from the 1838 edition of  “The History, Antiquities, Topography and Statistics of Eastern India; Vol 2: Goruckpoor section, by Robert Montgomery Martin. [1]. The section on Dinajpur gives further information about the tiger killed there: Continue reading

TEN Common Myths About White Tigers – Debunked !

TEN Common Myths About White Tigers – Debunked !

10 Common Myths about White TigersSo much misinformation, where to start ? Here are the 10 most common myths circulating about White Tigers, with the reasons why they are indeed myth not truth. This is only a brief look at the issues – see the FACTS tab above for the serious details (a work in progress !).

IMPORTANT NOTE: There is scientific and/or historic proof for the statements made in this article. Please click on the “MORE INFO” links in the text below for a more in depth explanation of the issues – there you will find citations and links to back up what is stated.

 

Myth #1: “White Tigers never occurred in the wild, they are a man-made breed”.

White Tiger in Captivity 1920

White Tiger in Captivity 1920

History debunks this one easily. There are literally dozens of reputable records of white Bengal  tigers in the wilds of India over the last 200 years – most were shot for trophies, so there was a skin to prove it. A very few were captured alive, and a few were even photographed. We have records from the Proceedings of the Zoological Society of London; from the Journal of the Bombay Natural History Society; writings from prominent naturalists and zoologists of the times. There are even ancient records going back 400 years and more. The last-known wild white tiger was shot in 1958.

MORE INFO – History of White Tigers in the Wild

Myth #2: “The ONLY way to produce White Tigers is by continual inbreeding, mother to son, brother to sister etc.”.

The science of genetics proves this myth false. The white coat is not caused by inbreeding, but by normal genetic inheritance from the parents. The gene for white coat follows a simple Mendelian recessive inheritance pattern. This means that you can outbreed them to unrelated orange tigers, creating a diverse gene-pool of orange tigers that are white-gene-carriers. Mating 2 carriers, or a carrier with a white tiger, can produce healthy white cubs without any inbreeding at all. This is quite natural, and probably how it occurred in the wild.

MORE INFO – White Tiger Genetics – the Basics

Myth #3: “White Tigers have no conservation value”.

Science differs again. Over the last few years, geneticists have been busy testing DNA samples of wild tigers, captive tigers, and long-dead tigers (from skin and skull samples). They’ve come up with some VERY interesting findings, like:

  • Tigers in the wild have lost 93% of their genetic diversity.
  • Captive tigers hold genetic diversity that no longer exists in the wild.
  • White Tigers (!) hold DNA variations that no longer exist in the wild.

We all know (don’t we?) that genetic variation is key to species survival, which makes every bit of variation left to the tiger extremely important to conserve – both in the wild AND captivity.

(There is another subtle myth embedded in this one – that conservation is the only thing that matters. More about that another day!)

… MORE INFO – Recent Genetic Research

Myth #4: “White Tigers cannot survive in the wild because they have no camouflage”. 

camopic1Well this seems to makes sense – or does it ? Only superficially. How does an orange Amur tiger survive in the snowy whiteness of its natural winter habitat ?

The historical evidence from #1 above tells us that White Tigers did indeed survive – and thrive – in the wild. Many of those shot were adult animals described as “in the prime of their life”, and some were females with cubs. There was known to be a “regular breed” of White Tigers living and breeding in Central India.

Camouflage is not just about color. Most white tigers still have stripes which break up the body appearance. Many prey animals do not see in color. The ability to move silently and to anticipate the behavior of prey is not affected by coat color. Tigers do not only live in deep dark jungle, they also inhabit drier more open areas, where the undergrowth is bleached pale in Summer;  pale rocky riverbanks and mountains; and they love to use roads and tracks to travel by. They are masters of the hunt, and very adaptable.

MORE INFO – How did White Tigers Survive in the Wild and History of White Tigers in the Wild

Myth #5: “ALL White Tigers are In-bred”.

This is a rather sweeping allegation to make – and never backed up with proof. Perhaps this assumption is a relic from the 1970’s, or perhaps it’s a (false) conclusion drawn from Myth #2.

While I will not make the claim that the opposite is true – all the time, everywhere – there is scientific proof that not all white tigers are inbred at all. This comes from a genetic study published in 2013 that found the level of heterozygosity in white tigers to be comparable to that of orange tigers – and concluded that the white tigers studied had indeed been outbred to unrelated orange tigers as described in #2 above.

… MORE INFO – Recent Genetic Research

Myth #6: “All White Tigers are not pure-bred”.

White Bengal Tiger in Bangalore

White Bengal Tiger in Bangalore

Another sweeping statement that falls down under closer scrutiny. White Tigers in India are pure-bred Bengal Tigers – myth #6 ignores this completely. In USA, White Tigers are assumed to be Bengal/Amur mixes – but there is no definitive proof that this is so for all. In fact, those busy genetic researchers have recently found that some USA captive tigers assumed to be cross-breeds are actually pure-bred ! Whether this applies to White Tigers or not remains to be investigated (or published).

There is another problem with this myth – it implies that not being pure-bred is a terrible no-no. That is a matter of debate, experts hold differing opinions, with some recognizing that the mainland tiger division into sub-species is a recent event, caused by human-induced segregation of a previously continuous and clinally varied population. Others state that preserving the “pure” subspecies may be a luxury the tiger cannot afford, and it may be necessary to cross-breed for the long-term survival of the tiger.

… MORE INFO – Recent Genetic Research

Myth #7: “White Tigers are SO recessive that breeding 2 White Tigers produces many excess orange cubs which are then destroyed.

White Tiger Cubs at Moscow Zoo

White Tiger Cubs at Moscow Zoo

This is a 2-pronged myth, both parts resulting from a lack of understanding of the genetics involved. The word “recessive”, when used in everyday conversation, implies something backwards or defective – as in an economic recession. However, the term as used in the science of genetics means something quite different – it is the opposite of “dominant”. When a recessive gene is paired with a dominant gene, the dominant trait will mask the recessive. Recessive genes can be either good, bad, or indifferent – they are not inherently faulty. It is this specialized genetic meaning of the word recessive that applies to White Tigers, not the more general meaning from everyday conversation.

Basic Mendelian genetics debunks myth #7. Two White Tigers bred together can only produce white cubs, because they do not possess the orange gene that is required to make orange cubs.

Furthermore, when orange cubs are produced from outcrossing, these cubs are valuable to White Tiger breeders because they carry the white gene – they are not excess !

MORE INFO – White Tiger Genetics – The Basics

Myth #8: “White Tigers are mutant freaks”.

No. A white cub is not produced by spontaneous mutation – it is produced by natural genetic inheritance from the parents (check back to #2).

The white gene is thought to have been caused by gene mutation at some time in the past – 100’s of years ago, or 1000’s or…. we don’t know when. Mutation is normal and necessary for evolution and genetic diversity. The gene that produces white coat in tigers has recently been identified (2013), and it is the same one that causes white skin in humans, white chickens, etc.

… MORE INFO – Recent Genetic Research and White Tiger Genetics – The Basics

Myth #9: “The white gene causes defects and low survival rate – 80% of white cubs die“.

Where on earth did that “statistic” come from ? There is no data from the last 20-30 years to corroborate it. My best guess is that it is harking back to the 1970’s when zoos were inbreeding their tigers and finding out the hard way that that wasn’t going to work long-term. The important point is that it was the inbreeding causing the problems back then, not the white gene itself, and as we’ve seen it is not necessary to inbreed (and should not be done!) The same scientific research that identified the white gene in 2013 also concluded that it affected only the color, and did not cause any defects.

… MORE INFO – Recent Genetic Research

Myth #10: “White Tigers are not a separate species or subspecies and therefore not endangered”.

This is still a grey area, but it is generally accepted that it is not a separate sub/species, but part of the natural variation of the Bengal tiger subspecies. This is actually beneficial to the White Tiger, as it means that you do not have to breed White Tiger to White Tiger, but can outbreed to other orange Bengal tigers. This means a much more diverse gene-pool available for healthy breeding.

The tiger as a species is endangered, with only a fraction of its genetic diversity left, so the White Tiger is an important part of genetic variation of the Panthera tigris species.

… MORE INFO – Recent Genetic Research

Bengal Tigers at Mysore Zoo

Bengal Tigers at Mysore Zoo