by Dr. K. Ullas Karanth
Wildlife Conservation Society - India Program
The following has been excerpted and reproduced from: "In Danger—Habitats, Species and People" Paola Manfredi, ed. (Ranthambhore Foundation, India, 1997) with the permission of the author.
• Evolution and RadiationOn a cool October dawn in 1994, I drove along a forest road through my study area in Nagarahole, wearing earphones which blocked out all the delightful bird calls which filled the sun-dappled jungles around me. Concentrating intensely on radio signals coming through a receiver slung over my shoulders, I swung my hand-held antenna to capture these tinny beeps which sounded exactly like the green barbet's calls, which I was filtering out. The signals emanated from a tiny radio transmitter around the neck of a tigress named Sundari, whom I had collared five years earlier. Having 'fixed' her location, I now knew she lay concealed in a thicket of lantana about 30 metres to my left. I had positioned my green Gypsy between the tigress and a herd of gaur cropping the lush green themeda grass on the roadside clearing ahead of me on the right. I knew Sundari was hungry, having left her last kill about a week ago. I could imagine her inside the lantana thickets, her muscular form wound up like a coiled spring, waiting for the moment to strike. the gaur grazed placidly, the massive, deep brown forms of the adults, a striking contrast to the rich chestnut coat of a very young calf. They were a portrait of bovine serenity, except for an old cow who looked up from time to time. Suddenly, the radio pulses varied in value, as the tigress manoeuvred stealthily inside the thickets, positioning herself for the deadly ambush. As I looked around taking off my earphones, the tigress broke cover and bounded across the road, within a couple of metres of my Gypsy. As the 150 kilogram lethal projectile hurtled towards them, the gaur scattered into the heavy shrubbery which lay on their side of the clearing. But she had managed to gain that crucial, split second element of surprise, before she was upon them. Barely breaking her stride, the tigress darted into an opening in the dense cover. She was trying to intercept her victim, before the gaur herd rolled away like distant thunder. A moment later, I knew she had succeeded in securing her victim, when I heard the pitiful braying of the calf in its death throes blend with her fearsome growls. The thick shrubbery shook violently for a few seconds, and then became still. The rest of the herd milled around at a distance, their low throaty growls of fear filling the air.
Tiger is the most feared predator in its jungle domain. When we, the human species colonised Asia, tigers were already prowling in these forests, preying on deer, pigs, wild cattle and an ape as big as us—the orangutan. Like all these prey species, primitive men too probably feared the tiger. However, over the next few thousand years, humans culturally graduated from being primitive hunter-gatherers to master agriculture and animal husbandry. By cutting or burning down the forests in which tigers lived, humans gradually turned much of the landscape inhospitable for tigers. Primitive hunters even developed an ingenious array of techniques such as snares, pits, nets, spears and dead-fall traps to kill tigers. With the advent of the industrial revolution, human weaponry against the tiger expanded to include explosives, fire-arms and chemical poisons. The tiger's naturally endowed weapons—strength, speed, stealth, nocturnal vision, teeth and claws—were no match for the lethal inventions of the clever apes invading its habitats. Today, man's technological mastery over the tiger's fate is so complete, and yet his passion to tame the jungle so strong that many fear the tiger's roar may soon be silenced forever in the Asian forests. Because, for all its aura of invincible power, the tiger is a fragile species. Paradoxically, the tiger's ecological fragility is ordained by nature through the very same traits we fear—large body size and a carnivorous diet.
EVOLUTION AND RADIATIONBig cats like the tiger do not evolve out of thin air, overnight. Throughout the earth's geological history (4.5 billion years), large scale forces of nature such as global climate change, movements of continents, and geological variations induced by sun, rains and the winds, gave rise to a variety of life forms including a diversity of plan communities. An even more diverse array of herbivorous animals, ranging from tiny grasshoppers to giant elephants evolved to crop this vegetation. This complement of herbivores included several large mammals ancestral to the present day deer, pigs, wild cattle, tapirs, rhinos and elephants. Such a community of ungulates is not a mere collection of individual species, but an intricate, ecological web in which large species feed on coarser plants, providing paths and access for smaller ones, and each ungulate specialises to feed on different plant species, plant parts or different stages of plant growth. In parallel, complex communities of large carnivorous mammals evolved from a civet-sized Miacid ancestor, about 40 million years ago, to exploit this diverse prey base.
All large predators (killers of prey much bigger than themselves) have evolved two basic hunting strategies: cursorial or stalk and ambush. Cursorial predators are built to chase prey over long distances and bring it down through exhaustion. The ambushers, on the other hand, are designed for stealth to get close to the prey, and for the short surprise rush. Barring the cheetah, all the other big cats—the tiger, jaguar, leopard, snow leopard, cougar, and, even the savanna dwelling lion—are essentially stalk and ambush hunters.
Evolutionary descent of the present day tigers has been reconstructed traditionally by comparing anatomical and skeletal features, as well as through more recent methods using molecular genetics. Geneticist Stephen O'Brien and colleagues who used 'molecular clocks' estimate that the genus Panthera tigris separated from the Pantherine lineage less than a million years ago. Based on the relatively primitive skeletal features of the tiger subspecies P.t. amoyensis now surviving in southern China, taxonomists argue that tigers originated in that part of the world. This idea is supported by the fact that this forested region also harboured a variety of large-sized prey such as wild cattle and Cervus deer species.
Ecologist John Seidensticker has elegantly explained the subsequent radiation of tigers into different subspecies as the evolution of 'ecotypes' adapted to different prey bases. Siberian tigers (P.t. altaica) which evolved to fit the coldest climates and kill large prey such as moose and elk, are big, furry and pale. Indian and Indochinese tiger subspecies (tigris and corbetti, respectively) which adapted to hot weather and preyed on abundant large ungulates in forest-grassland mosaics, are medium-sized, short-coated and darker. The extreme adaptation to humid rain forests, where most prey are small and scarce (such as muntjac and pics), is seen in the richly coloured island subspecies of tigers from Sumatra (sumatrae), Java (sondaica) and Bali (balica), which are barely larger than jaguars.
BORN TO KILL: PHYSICAL ADAPTATIONThe tiger must be big enough to knock down, subdue, and quickly kill a prey much larger than itself. Another advantage of large body size is the ability to drag away, hide and defend large kills against other predators. Siberian tigers can weigh more than 300 kilograms. The Indian tigers are smaller with average males weighing around 200 to 250 kilograms and females a 100 kilos less. Indian tigers are about 155 to 225 centimetres long including head and body, with an additional tail length of 75 to 100 centimetres, if measured correctly along the body curves. However, many old shikar accounts report a nose to tail-tip distance, measured straight between wooden pegs (and, as a way suspected, sometimes between pegs of whisky) making it difficult to get accurate size estimates from them.
The tiger's body structure (morphology) and internal chemistry (physiology) are, above all, evolutionary adaptations for predation. The tiger has to derive its energy needs for maintenance, growth and reproduction from the chemical energy stored in the body tissues and blood of its prey. Obviously, energy gained from the kill must exceed the energy expended in prey capture. Because catching small, scattered prey (rats, frogs or fish) involves energy loss higher than the energy which can be squeezed out of such prey, the tiger must meet most of its needs from large packets of energy—ungulates. However, large ungulates are always scarcer than rats or frogs. and can only be killed infrequently. Therefore, the entire physiology of the tiger is adapted to a regimen of enormous meals, at intervals of four to five days or even longer. A tigress I radio-tracked once went without making any substantial kill for two weeks. Tigers also save energy by lazing for over 15 to 16 hours a day, even when hungry. After making a kill, the tiger is virtually inactive for the next three or four days.
However, before the tiger can feed, it has to find the prey animal and kill it. This is not easy since most ungulates are extremely wary, and have acute hearing and a good sense of smell. To get within the striking range of ten to 30 metres without being detected, it takes all the skills a tiger possesses. The tiger's colourful contrasting coat of ochre and white, topped with black stripes, appears striking in a zoo enclosure. However, when it walks in the dappled shadows and brownish cover of the forest, the same contrasting patterns break the tiger's outline and blend it with the surrounding brush. Because tiger's ungulate prey cannot discriminate colours well, a still tiger is virtually invisible to them.
Other major predatory adaptations include padded feet, digitigrade ('on the toes') stance and a sinuous body, which permit to have a good sense of smell, they seem to depend on vision and hearing to locate prey. The structure of the tiger's eyes and nerves connected to them suggest that, although they probably see the world in 'monochrome,' their light-gathering ability (night vision) is extraordinary. Supplemented by long whiskers (vibrissae) to 'feel' their way around in dense cover, tigers can silently search for prey in a pitch dark forest. Tiger's acute hearing (with specially modified internal ear chambers and moving external pinnae), can detect and home in on the faintest sounds from an invisible prey.
A tiger's muscles can surge up the power needed to capture prey, but they get tired quickly in comparison with ungulate muscles. Bonded around the cat's strong bones and flexible joints, these muscles are only capable of a short rush, with lots of twisting, turning and flexing. A remarkable series of photos by Valmik Thapar show the amazing contortions of a tiger's body as it wrestles down a sambar. Even with our recent masters of robotics, it is hard to imagine any machine attaining such capabilities.
When a tiger takes down powerful beasts like gaur or sambar three to five times its own size, it must avoid getting injured by their flailing hooves or horns. To do so, the tiger manipulates prey, using its forelimbs with their sharp, sheathed, retractile claws. Even its hind paws can inflict serious damage in close combat. However, the cat's chief weapons of execution are its four dagger-like canine teeth. Strong jaw muscles anchored to the skull, stab the canines into the throat, neck, or the brain case of the prey, immobilising and killing it swiftly.
DISTRIBUTION AND BIOGEOGRAPHYThe Asian continent and the Sundaic Islands off it, are the home of the tiger. In the past, tigers were distributed widely, if somewhat sporadically, in an arc north of the Himalaya extending from China to Siberia and through some Central Asian republics into Iran. Another arc went southeast into Indochina, later branching into Myanmar and across India, before being halted by the Rajasthan deserts, Himalayan ranges and the Indian Ocean. A second branch of the same arc expanded into the Malay Peninsula and the Indonesian islands of Sumatra, Java and Bali. John Seidensticker has explained tiger distribution patterns in relation to changes in seal levels and land-bridge connections during the Pleistocene epoch.
Over its vast distributional range, tiger once occupied a truly diverse range of habitat types. These included both coniferous and broad leaved temperate forests in Siberia, subtropical woodlands in China, reed beds in the Caspian region, and the dense tropical wet-evergreen forests in Thailand, Indochina, Malaysia, India and Indonesia. Optimal tiger habitats included the tropical deciduous forests (both dry and moist) in the Indian subcontinent and South-East Asia. Tigers also colonised mangrove swamps (in India, Bangladesh and Java), and peat swamps (in Sumatra). Although they could not adapt to open arid regions (unlike lions and leopards), given some cover and water, tigers are quite catholic in their choice of habitat.
However, one key requirement must be met before and area can support tigers: an adequate prey base. An incomplete list of tiger's ungulate prey would include wild cattle (gaur, banteng, kouprey and water buffalo), other bovids (nilgai, chousingha, chinkara, takin, vu quong ox), wild goats and goat-antelopes (tahr, goral, serow), several species of deer (moose, elk, sika, sambar, barasingha, thamin, chital, hog deer, Tiomorese deer and muntjacs), tapir wild pig and occasionally rhino and elephant calves. Although tigers do kill smaller prey, ranging from prawns to peafowls, energetically, they cannot survive and reproduce if a habitat does not support ungulates at adequate densities.
ECOLOGY OF PREDATION: TIGER AND PREY NUMBERSScientific studies by George Schaller in Kanha (1964-65), Melvin Sunquist in Chitwan (1973-75) and my studies in Nagarahole (1986-95) have provided quantitative data on tiger predation. These show that a male tiger may require about 2,200 to 2,500 kilograms of meat over a year. Considering wastage and inedible parts of the prey, this works out an annual requirement of about 3,000 to 3,200 kilograms of live prey for an average tiger. To meet this nutritional need a tiger has to kill 40 to 50 prey animals/year, and a female raising three juvenile cubs may have to kill as many as 60 to 70 prey. Research on tigers (and other big cats) suggests that they can only crop about eight to ten percent of the numbers of prey available in any habitat. This ratio of predator to prey numbers is related to the rates at which ungulate prey replace themselves, other mortality factors, ad to the fact that tigers have to survive off the incremental growth. Biologist Louise Emmons, who compared big cat and small cat predation in South American, showed that the latter can annually crop even 40 percent of their prey (such as rats) which reproduce much faster than the ungulate prey of big cats. This 'ten percent' thumb rule for big cat predation shows that to support a single tiger, a prey base of about 400 ungulates may be needed.
HUNTING BEHAVIOUR AND FEEDING ECOLOGYOn an average, a tiger kills once in seven to eight days, although a tigress with cubs is compelled to kill more often to feed her family. Soon after the hunt, the tiger drags the carcass into nearby cover and hides it from vultures and other scavengers. Tigers usually start feeding at the rump, and avoid mixing up the rumen contents and intestines with the fleshy parts consumed. If undisturbed, a tiger stays with the kill for three to four days, eating 50 to 80 kilograms of meat. Although tigers in Nagarahole consumed about 65 percent weight from most kills, the proportion eaten was much less with large gaur kills.
Radio-tracking studies in Chitwan and Nagarahole showed that although tigers can hunt through the day, they are less active during the midday hours, and are most active from dusk to dawn. Tigers noiselessly pad on animal paths and trails, trying to locate prey. In Nagarahole, tigers make winding sweeps through dense patches of cover and search the edges of clearings, trying to flush and catch resting or feeding prey. The final rush for capture is usually short (ten to 30 metres). However, in open habitats around the lakes of Ranthambhore, Fateh Singh Rathore and Valmik Thapar documented tigers coursing after sambar over much longer distances, hunting like lions do in African savannas. Having observed more tiger hunts than most others, they estimated that only one in every ten attempts was successful even under optimal conditions.
The initial impact of a tiger's charge knocks the prey down in most cases, to be followed by a swift bite to the throat, nape or the brain case. With large prey such as gaur or fambar, a throat bite is more commonly used, whereas, with smaller prey, particularly pigs, a nape bit is often used. Death results from strangulation, severing of arteries, breakage of the spinal cord or even from shock. My studies in Nagarahole showed that tigers do not randomly kill prey which they encounter. Although chital were far more abundant, Nagarahole tigers appeared to select disproportionately more gaur and sambar. However, at other sites, like Chitwan and Kanha, where large prey are relatively scarcer, chital appear to form a high proportion of tigers' diet. In Huai ha Khaeng in Thailand, ecologist Alan Rabinowitz noticed that, because local hunters had reduced the densities of banteng, sambar and hog deer, tigers barely eked out and existence, subsisting on muntjacs and smaller mammals.
If livestock are found in tiger habitats, they are readily killed. Rare but persistent man-eating behaviour of individual tigers has still not been explained fully, although Charles McDougal has carefully documented the phenomenon. Normally, a human being standing tall and erect, is not a part of a tiger's mental image of its prey, and does not evoke the attack response. However, once particular individual tigers discover human vulnerability accidentally, cats being quick learners, they may kill again. The fact that man-eating tends to be endemic in certain tracts suggests that such a behaviour may even be learned by the cubs from their mother. However, the reason for the historical rarity of man-eaters over large regions, such as in south India, still needs to be understood.
BEHAVIOUR: SPATIAL AND SOCIAL NEEDSLike all other animals, tigers have to find each other to mate, share food, or even to compete over resources. Sometimes, they have to escape to avoid encounters. Although they are solitary animals, tigers are a part of a society of their own, maintaining contact with each other through a remarkable chemical communication system involving spraying of scent and urine to mark their passage. Additionally, tigers use roars and other vocalisations to attract or avoid encounters. Contact is also maintained by scraping the ground and depositing scats (faeces) at prominent places.
A population of wild tigers comprises of animals belonging to different sex and age classes. The breeding females (also called resident or territorial) form the keystone of this tiger social structure. These tigresses hold on to fixed ranges of habitat containing high prey densities, monopolising the breeding within them. They mate with the large breeding males whose range may cover two to three female ranges. Then there are transient tigers, both males and females, who do not breed. After having dispersed away from its mother at the age of one and a half to two years, a transient tiger wanders back and forth through its natal range and surrounding areas, trying to establish a home range for itself. As transients grow older and bigger, they compete aggressively with the breeders, and, sometimes, manage to kill breeders and appropriate their ranges. However, many transients also perish in this process.
Tiger cubs are born (two to four per litter) in a helpless condition after a short 105 day gestation. They depend on mother's milk for the first eight weeks or so, after which the female takes them to her kills. They gradually acquire hunting skills over the next one and a half years, often learning from their mother's ways, so as to fend for themselves after dispersal.
Our present understanding of tiger social organisation comes from long-term scientific studies employing radio-telemetry conducted in Nepal's Chitwan Park by biologist Melvin Sunquist and David Smith during the 1970s. Their data have been later supplemented by telemetry studies in Nagarahole and Siberia. These new data suggest that the basic social patterns observed in Chitwan may vary, depending on factors such as prey density and vegetation type.
However,there is evidence that more breeding and transient tigers can 'pack' into a given area at higher prey densities. For example, in prime tiger habitats in Nagarahole, where ungulates occur at high density of 50 to 75 animals/square kilometres, I found that home ranges of breeding tigresses are small (ten to 15 square kilometres), and adult tiger densities can exceed 15 tigers/100 square kilometres. At the other extreme, in prey-scarce Siberian forests, female ranges may be larger than 200 square kilometres, and tigers densities correspondingly lower.
MORTALITY, SURVIVAL AND POPULATION DYNAMICSA commonly asked question is how long do tigers live in the wild? Not very long in the case of most tigers. Based on limited studies in Chitwan and Nagarahole, supplemented by anecdotal observations in Kanha by H.S. Panwar, the following simplified picture can be drawn. A tigress produces, on and average, a litter of three cubs once every two and a half years. Disease, starvation, fires, floods, other predators (including man), and infanticide (killing of cubs of a previous male tiger by a new male who has taken over his range), all take a heavy toll of cubs. As a result, only about 50 percent of them make it through the first year. Of those surviving juvenile tigers, most make it to the dispersal age. After dispersal, transients compete hard among themselves and with the breeders over kills, space and mates. Some of them disperse into farmlands and get killed. Probably 20 to 30 percent of transient tigers die every year. Only those transients who are strong or lucky enough, survive to breed. Male tigers are about five to six years old and females three to four years old when they start breeding. The average breeding tenure of females may be around sever to eight years, and about half that for males. Although some resident tigers can live to be 12 to 15 years old, the life expectancy at birth, for the average tiger may thus be only about three to five years.
Despite such high mortality rates, with an adequate prey base, tiger populations produce surpluses every year because of their basic biological traits: early breeding, short gestation, large litters and year-round, short (three to four weeks) oestrus cycles. In a prey-rich habitat, a breeding tigress probably replaces herself several times during her lifespan.
MAN AND TIGER: THE BRUTAL ENCOUNTERAs long as human population densities remained low, and the technological capability to extirpate prey species or hunt tigers was primitive, tigers were saved over much of their range. Their ecological adaptability and high reproductive potential ensured their survival. No doubt, even centuries ago, landscape modifications had rendered many productive tracts such as the Gangetic and Deccan plains of India, the rice belts of Thailand, Vietnam and Java, unsuitable for tigers. Yet, there remained extensive forests where unsuitable climate, topography, soil and diseases kept out agriculture and high human population densities.
The picture began to change with the colonial penetration of Asia in 18th and 19th centuries, when fire-arms teamed up with the traditional hunting skills, enabling the colonials, kings and commoners to launch a war of attrition on tigers. At the same time, political stability and improved drugs against epidemic diseases increased human population densities, opening up hitherto inhospitable areas to intensive agriculture, often with new crops like sugarcane, coffee or tea. Probably the only positive factory favouring tigers in this era was the banning of shifting cultivation and protection of extensive wooded tracts as government owned 'Reserved Forests' which could not be cleared and farmed by the expanding human population. Therefore, despite considerable unsustainable logging by forestry departments, by the middle of this century, most remaining tiger habitats in India and Burma survived only in Reserved Forests. During the same period, in the absence of any protection to her forests against agricultural invasion, China lost most of its tiger habitats, while relatively lower population pressures alone saved tiger habitats in parts of Thailand, Indochina, Malaya and Sumatra.
By the middle of the 20th century, the Bali tiger subspecies was driven to extinction. When India gained independence in 1947, tigers were in full retreat. There were official bounties for killing tigers, enticing villagers and tribals to shoot, poison or otherwise slaughter tigers at every opportunity. The 'Grow More Food' campaign encouraged the honey-combing of remaining blocks of tiger habitats with agricultural enclaves, setting the stage for endless man-tiger confrontations. A liberal issue of gun licenses under this campaign added to the decimation of ungulates already caused by the more 'traditional' techniques. The advent of jeeps and dry cell torchlight in the post war era provided new tools to aid the poachers of tigers' prey. Simultaneously, licensed 'sportsmen,' both foreign and Indian, contributed their own unsavoury bit to the massacre. A well-known taxidermist estimates that during the 1940s he annually processed over 600 tiger skins for 'sportsmen.' A flavour of this era can be got from the fact that even less exalted bounty hunters, like my old friend nicknamed 'Naribodi' (tiger shooter) Chengappa, killed 27 tigers in the vicinity of a single village close to Nagarahole between 1947-64.
In the early 1960s, as a schoolboy helplessly witnessing the terminal period of this war on wildlife, I was certain that tigers would be extirpated during the next decade. What made the situation seem so utterly hopeless was the fact that, other than a few 'elitist' conservation pioneers, like E.P. Gee, Salim Ali, Billy Arjan Singh, Zafar Futehally and M. Krishnan, nobody seemed to realise or care about what was happening to India's wildlife. In 1967, George Schaller from Wildlife Conservation Society, New York, completed the first ever scientific study of tigers. Besides elucidating key facets of tiger's ecology, Schaller forcefully drew attention to the tenuous status of the animal, through his classical study 'The Deer and the Tiger.'
THE FIRST TIGER RESCUE: 1970-1990In response to concerns of the international conservation community about the imminent extinction of the tigers, several Asian governments duly passed laws protecting themin the early 1970s. However, effective on-ground protection materialised only in a few reserves in India and Nepal. In India, a fortuitous combination of three factors—the committed political leadership of Prime Minister Indira Gandhi, the campaign by a small but informed wildlife lobby and the presence of a disciplined protective force in state forest departments—led to the actual implementation of the new wildlife laws in several reserves. At least in these refugia tigers, their prey and habitats were protected. With the partial exception of Nepal and USSR, other tiger range countries lacked the necessary ingredients for effective tiger protection. Consequently, over most parts of Asia, the tiger's decline continued. The Javan and Caspian tigers blinked out in the 1970s, even as international campaigns to save the tiger were launched.
To learn the right lessons for the future from this conservation history, it is important to analyse the factors anchoring the Indian tiger rescue effort. The most effective component of this effort was the practical, protectionist orientation given to the whole enterprise by Indian foresters who had to implement the new wildlife laws. Pioneers like J.J. Dutta, Saroj Raj Choudhury, Kailash Sankhala, Sanjay Deb Roy, H.S. Panwar, Fateh Singh Rathore and others charged with the task of protecting tigers did the most obvious, common-sense things. Controlling the hunting of tigers and their prey by employing sufficient, well-equipped guards in tiger reserves was one step. Reducing biomass exploitative pressures on tiger habitats by curbing cattle grazing, forest fires, removal of timber, firewood and non-timber forest products (MFP) was another. At least in the designated Project Tiger Reserves, their directors even succeeded in stopping official logging by their forester colleagues. Another farsighted measure was the attempt to reduce human population densities within tiger reserves, by relocating human populations away from prime tiger habitats. Although this protectionist thrust of early tiger conservation efforts was sometimes inimical to the short-term interests of local people, the fact that tigers and the entire wildlife communities around them benefitted immensely from this thrust is a certainty.
Dramatic recovery of habitats, followed by a strong rebound of prey and tiger populations, was witnessed in the first decade of protection (1974-84) in many tiger habitats both inside the Project Tiger network (Kanha, Ranthambhore, Corbett, Manas, Kaziranga) and outside it (Nagarahole, Anamalai, Dudwa, Bandhavgarh). In protected areas exposed to tourism, like Kanha and Ranthambhore in India, or Chitwan in Nepal, visitors could even crowd around and watch tigers from atop jeeps or elephants. The flavour of those heady days is beautifully captured in the superb photographs and movies shot by Belinda Wright, Fateh Singh Rathore, Valmik Thapar and others. By the early 1980s this situation gave rise to a sense of complacency, with the Director of Project Tiger rhetorically asking, 'What do you do after you have succeeded?' International conservation bodies, eager for a 'success story' rushed around claiming that they had 'saved' the big cat. Nobody realised that these few hot spots of high tiger density represented only a minuscule fraction of total tiger habitat. Over the rest of its range, the tiger's decline continued.
IGNORANCE: THE MOTHER OF COMPLACENCYAlthough the hierarchical, authoritarian mind-set which characterised the Indian forestry departments was a major factor underlying the effective implementation of tiger protection in Indian reserves, the same insular mind-set also filtered out any possible infusion of wildlife science into tiger conservation measures from the very outset. For decades, Western ecologists had known that objective monitoring of animal populations is essential for evaluating the success or failure of any wildlife management programme. Realising early that it is impossible to count all individual animals over large areas, ecologists developed several standardised sampling techniques to objectively estimate animal population densities, or, at least, to measure population trends.
Ignoring such objective, sampling-based techniques right from the beginning, Indian park managers set about the impossible task of counting every single individual of an elusive, low density species like the tiger on a countrywide basis. For this enterprise they even invented a simplistic, completely invalidated method called 'pugmark census.' Essentially the method assumes that track impressions of all tigers in India can be collected simultaneously, and from that collection each individual tiger can be distinguished and counted. There is, of course, anecdotal evidence that some individual tigers can be identified from peculiarities of track shape, by experienced field men, if all four tracks can be seen imprinted on fine dust on hard substrate. The problem, however, is with the assumption that every tiger can be identified this way, a premise which has never been validated even on zoo tigers. In fact, in limited validation tests carried out by me, this assumption failed.
Compounding this basic false premise are ground realities such as a 15 to 20 percent annual turnover of individuals in a tiger population, variations in track shape caused by differences in soil, speed of the animal, collection of multiple prints of the same paw, and absence of suitable tracking substrate in most areas. Consequently, the tiger 'numbers' which were touted to 'prove' the success of conservation efforts, bore no logical relationship to real tiger numbers. Worse still, these seemingly exact numbers which were derived so easily, made the more complicated task of applying good science to tiger conservation seem totally unnecessary.
How does one apply good science to tiger conservation? To estimate densities of prey animals in the forest, I got several three kilometre long straight trails (called transects) cut through forests of Nagarahole. At dawn, I walked at full alert along these transects, scanning the forest for animals. Every time a gaur, sambar or other prey animal was seen, I recorded the species, number and the distance from the animals to the transect line, using an instrument called a range finder. After about 460 kilometre distance had been covered on the transects (with six assistants, over two weeks), these data were used to estimate the area covered in sampling, and the population densities of herbivores. Karnataka's forest rangers who worked with me were able to calculate densities of different ungulates accurately using this 'line transect sampling.'
By walking along forest roads which tigers patrolled regularly, my field assistants and I collected tiger scats (droppings), which, although they smelled like hell, were a mine of information on tigers. Since more tigers in an area meant there were more scats to find, a simple index of number of tiger scats seen for every 100 kilometre walked could be derived. This simple index could not tell how many tigers were in an area, but by accurately reflecting increasing or decreasing trends, it provided all the information which a park manager really needs to monitor his tiger populations objectively.
To identify individual tigers without any confusion, the best way is to use camera-traps, which are fixed on forest paths to be electronically triggered by the tigers themselves. Their dramatic self portraits show stripe patterns which are unique to individual tigers. Such identifications can then be used to estimate tiger populations in an area accurately, particularly if used in combination with 'capture/recapture' computer models which can analyse the frequency with which tigers repeatedly appear.
To know basic facts such as sizes of home ranges of tigers, hunting frequency, use of corridors, dispersal routes, long-term survival rates, and to observe their behaviour closely, radio-telemetry is an invaluable tool. Equipped with a receiver slung around my shoulder and a hand-held antenna, I covered Nagarahole forests driving on elephant back or on foot every day, radio-tracking my four collared tigers. With this technique I was able to enter the secret world of tigers, an impossibility otherwise in the dense forests of Nagarahole.
Findings from Chitwan's tiger research project, and later from the work in Nagarahole, showed up inconsistencies in the results of Indian tiger censuses. However, a decade ago, tiger policy makers and managers chose to ignore all criticism. They were equally apathetic to exploring alternative techniques: simple trend indices of tiger sign, prey density estimation or direct estimation of tiger densities using camera traps.
THE SECOND TIGER CRISISBy early 1990s, several adverse socio-economic factors combined to seriously undermine tigers. The three pillars of the earlier limited success were collapsing. Political support for wildlife conservation weakened under successive prime ministers. The tough, no-nonsense field managers at the bottom gave way to the smooth-talking officers more at home in the new political cultures which emerged. The pro-wildlife lobby of the 1970s was subsumed by a larger and more vociferous 'environmentalist' lobby which, despite paying lip sympathy to the cause of 'biodiversity,' fought to promote market-driven forest biomass exploitation by local people.
Internationally, major conservation groups and funding agencies, prodded to be politically correct by social activists who knew little and cared less about wildlife issues, began advocating 'sustainable use' of even the three percent land earmarked to be the last refuge of tigers. An international symposium to mark the 20th anniversary of Project Tiger in Delhi turned into a forum to debate 'people's needs,' while the tiger's own minimum ecological needs receded from the minds of the participants. An official documentary crowed that 'all was well with the tiger.' To say the least, this complacency was misplaced. In fact, in addition to the traditional pressures of tigers, a new threat was raising its ugly head: the burgeoning demand for tiger bones to supply the medicine men of the Far-East.
The initial disquiet of a handful of tiger conservationists, based on scattered evidence like illogical census results and poaching of known tigers in Ranthambhore, gave way to serious alarm by mid-1993, following the relentless efforts of Delhi based tiger conservationist Ashok Kumar and his undercover agents at uncovering hard evidence of large scale tiger poaching in India. Although the Director of Project Tiger, initially maintained that the tiger was not a 'dying patient' and 'continued to be perfectly safe,' mounting evidence from wider investigations showed otherwise. The true extent of this poaching or its impact are still unquantified in the absence of reliable estimates of tiger numbers and the numbers poached. However, it is clear that there is certainly no room for such complacency any longer. As the Indian Minister of Environment finally admitted, 'there is a serious problem.' The question is, are we doing anything about it?
REVERSING THE TIGER'S DECLINEThere are those who argue that loss of genetic variability caused by habitat fragmentation may become a long-term threat to some tiger populations. Others believe that only 'people friendly' conservation policies can save the tiger in the long run. But as Lord Keynes said, in the long run we will all be dead anyway, and we must not ignore the immediate crisis on hand. By over-emphasising long-term threats to the survival of tigers and thereby diverting scarce resources towards those, we may in fact be dooming the species to extinction in the next couple of decades.
My research on tigers in Nagarohole, in conjunction with those of biologists Melvin Sunquist, George Schaller and Alan Rabinowitz show that the low number of tigers over much of Asia is caused by the loss of their prey base due to hunting by people. Superimposed on this decline, poaching of tigers for the 'traditional medicines' (bone trade) may now be driving the final 'coup de grace' to the big cat.
As we now know, tiger home range sizes, densities and survival rates are all strongly linked to the maintenance of high prey densities. There is evidence that at higher densities, big cat populations can even withstand some degree of hunting pressure, because of the presence of 'surplus' transients. With lowered prey densities this 'buffer' of transients is lost, home ranges becomes larger, numbers of breeders decline, recruitment drops, and the tiger population becomes increasingly vulnerable. Ultimately, although a few individuals may linger on for a decade or so, extinction is dramatic and final, as the exit of the Javan tiger showed us two decades ago.
It is obvious that the tiger cannot change its natural traits, large size and carnivorous diet, to accommodate our changing policies. Either we accommodate the tiger's biological needs into our world view, or the big cat will go extinct. Therefore, the strategy to prevent tiger's extinction has to be built around this vulnerable species' ecological needs rather than around social attitudes which we perceive to be politically correct. This inevitably means making several tough, unpopular decisions.
Firstly, we have to recognise that tigers cannot coexist with high density human settlements living off market-driven economic activities like agriculture and forest biomass exploitation. Therefore, human and livestock population densities need to be reduced inside prime tiger habitats through sensible and fair relocation policies, to allow wild ungulate prey to recover from habitat pressures, poaching and competition with livestock. It is even worth sacrificing some non-priority forest areas to accommodate such relocation, if critical tiger habitats can be physically isolated from poaching and habitat pressures.
Secondly, recognising that market-driven biomass exploitation is the leading cause of habitat deterioration, all linkages between tiger reserves and local or distant markets for forest biomass derivatives such as fuel, timber, fodder, dung and other 'minor' forest products should be snapped. Moreover, this forest-market linkage must be broken, regardless of whether the agencies extracting such products are governments, NGOs or local people.
Thirdly, we need to appreciate that, despite our best social engineering efforts, there will always be criminals in any society, who can only be stopped through effective use of force. Therefore, our effort to promote eco-development around tiger habitats has to be balanced by adequate investments in manpower and material resources for policing the tiger habitats. Threat from poachers operating inside tiger habitats, and, the threat from distant wildlife traffickers should both be ruthlessly countered.
Fourthly, we have to critically and continuously evaluate how our tiger conservation efforts are faring, by employing universally accepted methods of science. For this, our policy makers have to shed their intellectual apathy, and weave the science of wildlife biology into the fabric of conservation strategies.
Finally, without a committed political leadership and public awareness, it is impossible to usher in any such major changes. The only force which can perhaps induce the necessary attitude changes among the politicians, officials, media, social activists and the public, is an articulate, passionate 'tiger lobby' which clearly understands the ecological fragility of the feared predator.
When I see a tiger pad silently through the forest brush, literally melting into it, a deep sense of admiration and awe steeps through me, which no captive tiger can arouse. I cannot but help feel that it is this elemental passion we all feel for its wildness, one way or the other, which can either save the tiger—or destroy it forever.
WHY SAVE THE TIGER?There are several sensible arguments which can be marshalled to justify why we should save the tiger. For instance, the productivity and welfare of our predominantly rural, agricultural society is critically dependent on the regulation of run-off and soil erosion, on recharge of ground water, and migration of local climatic fluctuations. Forests, which clothe the watersheds of most of our important river systems, play a dominant role in performing these functions, besides harbouring the tiger. If wisely managed, some of the forested landscapes can also provide our rural and urban populations the fuel, timber, bamboo, rattan and a host of non-timber products, needed for their sustenance.
More importantly, as the earth's mineral resources are getting exhausted rapidly, the needs of food, fibres, shelter, fuels and life-saving chemicals needed by an expanding population seeking better lifestyles will increasingly depend on biotechnology. However, so far, scientists have explored only a tiny fraction of the rich forest biota, which is literally a treasure house of potential life supporting products. Tiger is a key species of these forests which harbour millions of plant and animal life forms. Moreover, the tiger is at the end of a complex chain of ecological relationships; this also includes plants which directly produce energy from the sun, and the herbivorous animals upon which the tiger preys. These relationships are so complex that it is virtually impossible to isolate and preserve only those life forms which may become useful to humans. One of the most effective ways of being sure of saving complex life form linkages and ecological processes is to ensure that top-predators, such as the tiger, are thriving in an intact assembly of predators, prey and plant communities. Surely, sacrificing the remaining three percent land on which tigers live now, to solve some problem or the other which society has not been able to solve despite full access to the remaining 97 percent over centuries, does not make sense.
There are other arguments one can advance: the last refugia of tigers are also wonderful natural laboratories to observe and from which we can learn. The tiger forests are our last links to a natural world from which we came, a rich source of education. They are an irreplaceable library of nature for generations to come, and advocating their destruction in the name of progress or temporary local benefits, is akin to burning down an ancient library.
However, for all their impeccable logic, the above arguments for saving the tiger are basically utilitarian and rather selfishly human-centered. In addition, I believe there are strong ethical compulsions for trying to save the tiger. Tiger (and other wildlife species) are products or millions of years of evolution. Global climate change, movements of continents, advance and retreat of glaciers, volcanic eruptions and other mighty natural forces led to the evolution and radiation of life on earth. During these upheavals, life forms evolved and died out, only to be replaced by new ones. However, humans have now so drastically modified the earth's landscape that the wonderful process of evolution has been virtually negated, for all but the smallest creatures.
The amazing process of natural selection (jokingly but appropriately attributed to a 'blind watchmaker' by evolutionary biologist Richard Dawkins) gave rise to a species like the tiger. Do humans who evolved during the last few 'seconds' of the history of life on earth, have a fundamentally superior moral right to wipe other species off the face of the earth? or do we have a moral duty to protect some fo these creatures on at least a tiny fraction of the earth's landscape? If the latter is the case, at least in its last refugia, the tiger's right to survive as species overrides the rights of individual men to extirpate them. I believe such preservationism is ethically justifiable under any moral or social code we can think of.