We know that white tigers did survive in the wild – but how ? The key is to view the world not as a human, but as the tiger and his prey. Recent discoveries indicate that their world is not as we see it – we need to re-think our old assumptions about camouflage !
The following is not intended to prove that white tigers survived in the wild – we already have that proof from the historic records. Rather, this is an exploration of facts that help explain how and why the white tiger was not disadvantaged by his coloring – or at least show how it is far more complicated than black and white.
Surely it is better to search for answers rather than deny a proven fact because we don’t understand how it is possible. We have so much yet to learn from and about the White Tiger !
1. Deer Vision v Human Vision
The Visible Spectrum
Human vision is trichromatic – we have 3 different types of cones in our eyes and can distinguish red/green/blue during daylight. Our lenses filter out most of the UV light, allowing for good daytime acuity – but we have poor night vision.
Some primates share our type of vision, but most mammals do not.
Deer are one of the tiger’s favourite prey. While we cannot actually experience the vision of a deer, we can make some educated approximations. Like most mammals, they are dichromatic. This makes them sort of red-green color-blind – but the trade-off is that they see better in dim light than we do. They have a higher proportion of light-sensitive rods, and a reflective layer called the tapetum which reflects extra light back into the eye. Although their acuity is not good and stationary objects can be difficult for them to see, they are highly sensitive to seeing movement, which they can see in about a 300 degree arc around them. We think they see in muted blue/yellow/grey by day, and shades of grey at night.
This suits animals like the deer and tiger very well, as they are mainly active during the dimmer light of dawn and dusk. Noticing motion, scent and sound are more important than high resolution colour vision for the deer in order to avoid predation.
The human eye filters out ultraviolet light – we do not see it – and until recently it was thought there were only a few mammals who could (eg reindeer, bats, rats). However, recent research has found that many other mammals’ eyes do not have the UV filters, indicating that they also see UV to some extent (eg deer, pigs, cattle, cats, dogs). This makes sense in the context of dawn/dusk activity and the need to utilize all sources of light available. (The % of UV light is higher at dawn/dusk/in shadow although the overall amount of light is less than in full sunlight.)
Most references to UV vision in animals (and birds) are concerned with the extra vision it gives them, things they can see that we can’t. But just as important is what can be hidden by UV absorption.
We can see a similar effect in the UV-absorbing sunscreen adverts, where a fair-skinned model applies white sunscreen – with UV photography the sunscreen coated skin appears black. Or the UV photos illustrating a bee’s vision, of flowers that show dark coloration where we see only pure white petals.
When white animals are not camouflaged against white snow, it is clear we need to re-think our theories and assumptions about camouflage !
I have found no specific reference to the UV absorption factor of tiger fur, but as it is not color dependent it is likely white and orange fur absorb at about the same rate.
2. How does all this help the White Tiger ?
White Fur and UV Vision
To deer, pigs, and other prey animals with UV vision, the white tiger may appear much the same as an orange tiger, blending in with the background with similar UV absorption rates.
Hunting Techniques and Strategy
The deer is highly sensitive to visual motion, sound, and scent, but has poor visual acuity. The tiger, that master hunter, uses techniques that take it all into account.
A stalking tiger seems to glide along the ground without dislodging the vegetation, her movements imperceptible, freezing immobile at the first sign of the deer’s immanent attention. She can creep and crouch low to the ground to minimize her shadow. She moves silently, each paw placed slowly and precisely to avoid even the slightest leaf crackle, and navigates the forest air currents to avoid sending her scent to her prey. She uses her experience and knowledge of the terrain to anticipate what her prey will do.
These techniques are not affected by the tiger’s coat color – if the tiger is motionless the deer will not see her. If the tiger is silent and upwind, the deer will not hear or scent her. The tiger does not have to be “invisible” all the time to all animals – color camouflage may be largely superfluous. Consider also that the orange Amur tiger survives very well in a habitat that is covered in white snow for part of the year.
Concealment v Camouflage
The tiger knows how to use every scrap of cover available, even humans have been surprised by how well a tiger can hide in ambush behind a small bush. Note that this is concealment, not camouflage – a tiger hidden behind a rock or a bush is invisible from the relevant direction whether she is orange, white – or pink !
Different Prey, Different Strategies
Although primarily a stealth and ambush hunter, the tiger is very versatile and will also attack prey that will defend or counter-attack rather than run away, such as buffalo or gaur. This involves no stealth or camouflage, the tiger relies on his wits, great strength and agility. Coat color does not matter here either – but the wild white tigers were generally larger than the orange, and this may have given them an advantage.
Artificial v Natural Conditions
A tiger prowling out in the open, in full daylight, is clearly visible to us whether white or orange, and today we only see the white tiger in artificial habitats created for our viewing benefit. But the wild tiger hunts in the forest at dawn/dusk/night. Visibility is markedly different in dappled forest light and shade, or moonlight, dawn and dusk.
Heavy jungle cover offers concealment without any need for camouflage, but the tiger also makes use of a wide variety of other terrain – pale rocky slopes, riversides, open forest that is bleached pale in summer, jungle tracks and roads.Other “White” Animals
We no longer have the opportunity to observe white tigers in the wild, but we can still study other black-and-white or white animals in their natural habitats.
For example, it is often asserted that white lions also could not survive in the wild due to their coloring but recently this has been proven false. Research by the Global White Lion Protection Trust found that white lions hunted just as successfully as their tawny brothers – in fact the white lions were slightly more successful than the tawny in moonlight.
(Is it possible the blue-eyed white lions and tigers can see better in the moonlight ?)The Malayan Tapir is another black and white animal, whose coloration is considered to be excellent camouflage in a moonlit jungle. The wide white band with black is considered to be disruptive, helping to disguise the body outline, and in it’s jungle habitat the tapir has been described as appearing “a strangely invisible misty grey”. The tiger’s black stripes are also thought to be visually disruptive, but given the poor acuity of some of its prey animals, it is also possible that the dark stripes on white background blur into more of an overall grey.
Advantages of a White Coat ?
Blending in is not the only reason for coat colors and patterns. There have been studies suggesting that the black and white stripes of the Zebra deter flies and may be useful in cooling through use of convection currents. Both applications would benefit the white tiger.
The unfamiliarity factor is another possibility. If we glimpse a flash of tawny gold in an Indian forest, we immediately think “tiger !”. But a glimpse of white is more likely assumed to be human clothing or white cattle. Although we now know there were dozens of white tigers in the wild, this was not well-known 100 years ago. People were not expecting to see white tigers, some did not even believe they existed. When one was killed, it was not unusual for it to be reported as “the first one ever known”.
This factor may have hidden the white tiger in (almost) plain sight – for a while anyway. The white tiger persisted for a long time, despite heavy hunting of the tiger overall.
Prey also get to know and recognize their predators – and lose this recognition if the predator is wiped out. Perhaps some prey could not easily recognize the white tiger as a tiger. Some will even approach an unfamiliar sight out of curiosity.
A news report from India in 1924 describes this factor in action – a white tiger that was often mistaken for one of the cattle it had killed.
A cursory look at the white tiger gives the impression that it “could not possibly have survived in the wild as it has no camouflage”.
After all, we know that they did indeed survive – and breed – in the wild for 100’s of years at least. Imagine how much can we learn from the White Tiger – and about the tiger in general – when we stop denying this simple fact, and start researching the reasons.
References and Further Reading
David M Lavigne, Life or death for the harp seal, Nat Geo 149(1) p137. 1976.