The Nagarahole National Park is at the centre of international research to determine the factors that can help reserves all across Asia nurture their tigers.
IN the still January evening, the view from the watchtower overlooking Mavinahalla tank in Nagarahole National Park was beautiful but unremarkable. It was too early at 3.00 p.m. for the green imperial pigeons to arrive. Common langurs lolled close to a salt lick, amusing themselves with mock chases and somersaults while sambar and spotted deer wandered languorously, a few of them giving the occasional cautious glance or raised-tail signal of nervousness. In the tank, a stork-billed kingfisher pursued a repetitive diving routine every few minutes, its prominent bright red beak, brilliant blue back and buff body glistening in the sun.
Just as the evening appeared destined for a quiet sunset, Ullas Karanth, well-known wildlife biologist looked towards the south view line and let out an excited whisper. "Tiger!" he said even as he remained glued to his seat, looking attentively through image-stabilising binoculars. A young male tiger, its golden brown coat glistening in the descending sun, was walking towards the watchtower along the view line, surveying the scene ahead. The atmosphere had suddenly turned electrifying. The deer had vanished and the langurs launched a series of alarm calls that grew progressively shrill as the predator drew closer to the tree that they were sitting on.
The tiger walked on, oblivious to the terror he was creating, but suddenly stopped and froze, looking up at the watchtower some 50 metres away. Seemingly disturbed by the presence of people, he paused for a few moments before turning westward. And then he was gone in a flash, his magnificent stripes melting into the lantana bushes. Life returned to normal in a few minutes in this part of the forest and the animals went about their normal business.
To sight a tiger in the 21st century in the deciduous forests of one of India's best nature reserves is a comforting reminder that with good science and effective conservation measures, this most charismatic animal, whose fate appeared sealed to many just a decade ago, does have a future. Until about 1964, gunshots rang out in and around Nagarahole regularly as bounty hunters pursued the big cat. "There was a bounty on killing tigers from the 1800s during the reign of Kodagu Kings almost up to 1964. There used to be a villager called Changappa who shot 26 tigers for such bounty from 1948 to 1964, just around his village on the edges of Nagarahole," recalled Dr. Karanth, Director of Wildlife Conservation Society's India Programme.
Today, this national park is at the centre of international research to determine the factors that can help reserves all across Asia nurture their tigers. It is led by WCS and actively supported by a forward-looking Karnataka Forest Department.
The Nagarahole study is part of a wider effort to understand what affects the fortunes of tigers in the wild. The key findings from many years of study of tiger populations nationally, which have been published by peer-reviewed journals indicate that in many sites, tigers decline in numbers because of prey depletion rather than being killed directly. Where adequate prey is available thanks to good protection measures (a tiger needs to eat about 50 deer-sized animals per year), their populations reach high numbers simply because the species breeds quickly.
If Nagarahole today has an estimated 60 tigers, which is considered a statistically valid number derived from modelling studies (based on average densities of 12 tigers per 100 square kilometres, 1996-2000 data), it is a tribute to two decades of work pursued by dedicated teams of researchers.
Progressive measures such as grant of lands to tribal people outside the park area for voluntary resettlement have reduced pressures and helped raise the prey numbers and as a consequence, the abundance of tigers.
Tiger ecology research has a history that predates by decades the peaking of interest in the animals after they disappeared in Sariska. India's dense old growth forests and the rich animal species that they held suffered irreversible losses during princely and colonial rule and even after independence for over two decades. As the most charismatic and prominent of the apex predators, thousands of tigers were shot for fun or profit, while another beautiful but less abundant cat, the Indian Cheetah was hunted to extinction early in the 20th century.
The turning point for conservation was the arrival of George Schaller, the legendary field biologist who brought with him a scientific research ethos that was absent here. The remaining tigers in the country got Schaller interested in the study of their life, habitat and behaviour. He came in 1963 under the auspices of Johns Hopkins University to, in his own words, "recapture India's past, when wildlife was abundant almost everywhere, when domestic livestock had not overgrazed the range, and when tigers were not the rare creatures they have become... .as a result of decades of ruthless slaughter." It is widely recognised that The Deer and the Tiger (The University of Chicago Press), Schaller's meticulous record of his work in Kanha National Park is a treatise of monumental importance in the annals of wildlife studies.
Schaller's path-breaking work inspired Dr. Karanth to launch a detailed study of tiger ecology in Nagarahole in Karnataka beginning in the late 1980s. Two decades on, his wildlife research is yielding data of vital importance and helping policymakers and scientists understand conservation concerns better.
At the core of the ongoing work in Nagarahole (and in the adjoining Bandipur and Bhadra reserves) is the issue of deciding tiger numbers and, as a corollary, the health of prey populations. Estimating tiger populations through traditional ways using pugmarks and sightings has proved to be unreliable in the past but this has been settled in favour of scientific approaches, particularly after the debacle in Sariska.
There is consensus among scientists that it is impossible to count every tiger. While Nagarahole alone is spread across nearly 644 square kilometres, the total range for tigers in Asia is a staggering 1.5 million square kilometres. The practical option for conservation professionals is therefore to sample tigers in the area of study with a variety of devices such as camera traps, radio telemetry, DNA analysis from scat and, potentially, dogs trained for scent recognition. The data are then used for statistical modelling to estimate the abundance (total number in a population) and density (individuals per given area). For estimates of prey populations, assessment methods rely on establishing transect lines in the forest and counting all animals seen along several kilometres of these.
Tigers eat a range of ungulate prey species — wild pig, spotted deer, sambar, gaur and muntjac in the south besides nilgai, barasingha, chinkara, wild buffalo and hog deer elsewhere. Researchers make the important assumption while drawing up conservation plans that prey populations are vital for healthy tiger numbers; and sampling yields reliable estimates rather than attempts to count all visible animals in a simplistic manner. Over the past decade and more, research teams have estimated tiger populations using a technique that employs sensor-equipped cameras to photograph the cats as they pass along identified forest paths. These images are useful because every tiger has unique stripe patterns much like human fingerprints that help differentiate them. During the survey season, photographic `capture histories' of several individual tigers are constructed, which also enable the use of statistical models that can estimate the proportion of tigers in the area that were photographed.
The conservation benefits of such research are clear. It has strengthened the theory on the tiger-prey link. Between 1995 and 2003, the WCS-led effort covered 6,820 km in 11 national study sites ranging from the highly protected alluvial grasslands of Kaziranga, moist forests of Pench-Maharashtra, Bhadra, Nagarahole, Kanha, dry forests of Melghat and Panna and the mixed forests of Tadoba and Bandipur. The results published in the Proceedings of the National Academy of Sciences, USA, in 2004 were revealing: The lowest tiger density, given as tigers per 100 square kilometres, was thought to be in Tadoba at 3.2 and the highest, in Kaziranga at 16.76. Even more striking, the study showed that tiger numbers could have been depressed because of pressure from humans on prey populations in Bhadra, Tadoba, Pench-Maharashtra and Melghat. At Panna and Bandipur, poor protection mechanisms appeared to have eroded the prey base. In Pench-Madhya Pradesh alone, it was evidently direct killing of tigers that had led to a serious reduction in numbers. Karnataka's support to such research has made the state a forerunner and placed it well ahead of other States.
The hypothesis of healthy prey populations determining tiger abundance was reaffirmed by a longer study in Nagarahole (1991-2000) by Dr. Karanth and his colleagues that was reported last year by the journal Ecology.
At Nagarahole, the work on collecting exhaustive data continues. Camera trapping of tigers, the key mechanism that helps assess abundance and density, is carried out methodically in 120 trap-sites at the rate of 40 sites every 15 days during an annual non-monsoon period when the population of the animal is thought to be unchanged.
"Studies based on camera trap capture and recapture can be done in most tiger reserves in India. But it needs the involvement of all individuals and institutions that possess the expertise and resources and not just the government," says Dr. Karanth.
This is an eminently feasible research agenda. There is a large pool of research talent with an impressive record of international journal publications; public support for wildlife conservation and tigers is high; there is sufficient funding for such programmes. What the conservation community looks forward to is a strong research bias at the Ministry of Environment and Forests and in the State Governments.
At the top of the list of conservation priorities must be the maintenance of high prey abundance in forests through strict protection; regular monitoring of prey numbers through line transect surveys; tracking of core tiger populations using reliable methods like camera trapping (which could have prevented the tragedy at Sariska by sounding an early alarm about reduced presence of tigers); preventing fragmentation, human impacts and conflicts through voluntary relocations of forest dwellers and other forms of habitat consolidation.
Nagarahole and its neighbouring reserves show that India can hope to save its megafauna for future generations despite mounting human pressures, if it understands the scientific basis of conservation. Without informed conservation policies, the MoEF, its agencies like Project Tiger and the State Forest departments will be unable to measure the success of their pro-wildlife actions.
THE first rays of sunlight filter in through the mist-covered canopy at base camp, close to the holding area of Nagarahole National Park at 7. Nagaraj N Bhat, a researcher with a particular interest in bats, prepares to set out with his men on his daily routine. His colleagues, C.M. Bipin and S. Sachin, engineers-turned-field biologists, will lead the other teams.
What lies ahead for the three groups is a demanding schedule that will see their teams drive across three different paths in the core area of the park, along which the Wildlife Conservation Society's camera traps have been positioned. The traps have two cameras facing each other on either side of the jungle path, linked by a sensor beam. They are set at a suitable height to capture side profile images of adult tigers and other animals that cross them during the night. A crossing animal breaks the sensor beam, triggering the camera. The system works because tigers have unique stripe patterns that help identify them
On the grind
Nagaraj and his teammates P.M. Vishwanath and Madhu get ready for the grind with soldier-like dedication. They carry a Global Positioning System handset, spare electrical supplies, cables, batteries and minimum rations and water.
Their job involves recording not just the number of "events" for each of the 18 camera traps in their line but also the numbers of animals such as spotted deer, sambar, muntjac, langur, elephants and wild pig they see.
Against a bracing wind, the team clad in camouflage jackets, trousers and caps sets off in a Mahindra jeep after a Spartan breakfast for the first location from base, which is identified by the GPS as 11.98682 N and 76.09354 E.
After travelling for 15 minutes, the team members stop at a trap point, and look a little concerned. An elephant has reacted to the cameras in the night. They point to one of the two olive green camera trap shells made of sturdy metal and embedded in a solid concrete foundation. It is bent to one side although the camera inside appears intact. Nagaraj thinks an elephant that was annoyed by the camera flash caused the damage. The sensor alignment has to be fixed for the cameras to fire again.
The team moves to the next location, Jalagadi Malada Dari, where the versatile Trailmaster controller (a programmable device that controls the camera trap functions) reveals that there have been six exposures in three days. Three of the shots are discounted because they represent test exposures made by the team. The others are most likely animals caught on camera.
It takes another 15 minutes to cover two more trap points. At each location, the team records its findings in a data form and then resets the controller, test firing the cameras for confirmation — one of the members holds a slate with the location details and date written in chalk for a cinema clapper board-style shot. On the Sunkadakatte-Mastigudi Road, the team is thrilled to find a pugmark. The camera trap nearby has also recorded an "event" overnight; it could be a tiger picture.
There are other tyre marks on the muddy road in this core area. The team thinks they could belong to a privileged tourism vehicle.
At the next camera trap, there is more encouraging news: the controller has recorded an "event" at 1.00 a.m. But the one ahead at Somayana Katte Road has none. As the jeep moves along, a couple of wild pig race into the undergrowth and this is noted down; tigers prey on these animals.
The team is thrilled at Sunkadakatte Road to find three "events" recorded at camera point SKR 16.2 around midnight. But the camera cables linked to the sensor and splitter are faulty and the team changes it in a few minutes. The fault and action taken must also be entered in the form.
After skirting the picturesque Kabini Lake, where woolly-necked and painted storks and a graceful tusker rest, it is time for lunch. It is 1.30 p.m. and the members climb up a watchtower overlooking Bisliwadikere tank for a quick lunch of tamarind rice, pickle, sliced onions and garlic pods. They watch playful langurs, a black eagle and a brahminy kite circle overhead before setting out again.
The day's findings
At a trap point on Kalappana Votkere Road, there has been an "event" at midnight. Nagaraj pauses to remove a tick that has caused a minor bite from under his watch and displays three more that have got on to his data entry sheets. He has been clearing fallen leaves and leafy camouflage from each camera point and ticks abound in these places. At Baraballe Road further down, there has been no event. A monitor lizard scurries off from the trap line. Camera point BBLR 02 is the last one at 11 96381 N and 76 1801 E.
It is just past three in the afternoon. The teams must put together the day's findings but it will take the entire cycle of 45 days to be completed before the films from the cameras are processed in Bangalore. There, the "events" will reveal themselves — as tigers, leopards, elephants, langurs, porcupines and other creatures that make Nagarahole a park to be treasured.