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In the public eye, white tigers (or more correctly, chinchilla tigers ) are perhaps the color which is most admired. The correct term for these tigers is chinchilla albinistic : blue eyed, lacking in phaeomelanin, pale-coated, but having a pattern. These tigers grow faster and heavier than their orange counterparts and with their pale ice blue eyes, white fur with chocolate stripes, pink noses, and pink paw pads they are indeed a beautiful sight. Unfortunately, beauty brings a curse and with the white tiger that curse is one of extreme inbreeding. The beautiful white specimen shown at the top of this page displays some evidence of breeding depression in having crossed eyes.
What causes white tigers?A white tiger can only be born when both parents carry the unusual gene for white coloring. The double recessive allele in the genetic code only turns up naturally about once in every 10,000 births. For unexplained reasons it seems to occur only in the Bengal subspecies although an orange Amur Tiger is sometimes believed to have carried the gene to his Siberian/Bengal hybrid descendents. Reports of white Amur or Siberian tigers have never been confirmed. Most likely these tigers are Bengal Tigers which have, at some point in time, been hybridized with the Amur subspecies, so polluting their genetic code.
Breeding DepressionDating right back to the first successful captive white tiger breedings, a trend was created which resulted in closely related tigers being mated in deliberate attempts to produce the valuable white specimens. At that time a Rewa white would sell for ten times the amount of an orange- colored tiger. Today, US$60,000 is not an unusual amount for a white specimen. Breeding father to daughter, and brother to sister, had the desired effect in that plenty of white cubs were produced, but it took a dramatic toll on the offspring. White Tiger HistoryMohan (the first captive white tiger to be successfully bred) was mated with Radha, one of his daughters from his second litter with orange-colored tigress Begum. This produced four white cubs: Raja, Rani, Sukeshi, and Mohini. Out of 48 subsequent white tiger litters, starting with those produced by Radha, 148 cubs were born. 105 of those cubs died without producing. 72 of these deaths arose from non-accidental causes. Typical signs of inbreeding include crossed eyes, curvature of the spine, twisted necks and shortened tendons in the legs. As inbreeding worsens, so the number of abortions, stillbirths, and unexplained infant mortalities rise. Cubs that do survive become prone to mysterious illness, while those that do survive to adulthood generally have a shorter life span than their more sturdy orange cousins. These are all problems orange colored tigers do not normally experience, though inbreeding is rife amongst some small pockets of wild tigers and with both the captive and wild populations of the South Chinese tiger.
OutbreedingThe problems caused by inbreeding soon had zoos searching for another option and this led to the decision to outbreed whites with orange tigers. Zoos then planned to mate their offspring, hoping for more whites to appear. This has proven reasonably successful in helping to overcome the previous problems. However, the situation is still far from perfect, and despite these changes in practice, breeding depression still frequently appears. The temptation to breed white tigers to white tigers is very high. This is due to the high value of the offspring. Some black market tiger farms consider the orange cubs to be of such little value they will kill all offspring which are not white.
See page Two about white tigers. |
