Tigers' Keepers

Craig Bares

Beyond a fence, down a 10-foot drop, across a moat, beside a rocky shore protected on both sides by steep cliffs, three young tigers romp on sun-dappled, green, green grass. There's something fairy-tale about the setting; the multiple physical barriers, the striking beauty of the residents--their eyes of fire, their garments of marigold striped with ebony, their faces showing nothing but royal disdain. No wonder William Blake exclaimed upon the tiger's fearful burning divinity; no wonder Shiva, the Hindu god of destruction and regeneration, clothes himself in a tiger skin; no wonder the tiger represents yin, the energizing force, in the Chinese I Ching. According to the I Ching, "The breath of the tiger creates the wind and the breath of the dragon creates the clouds; together they create the rain."

The three tigers frolicking this spring afternoon at the Minnesota Zoo make believable fairy-tale princes, stretching high up the sides of tree trunks to scratch signs in tiger code, rolling in the sun, their long white belly fur rumpled with water from the moat, carrying horse knee bones between their teeth as carelessly as you might carry a lollipop.The trumpets of peacocks, swans, and other noble fowl echo nearby, but turn your head for an instant to look for these colorful birds, and the tigers disappear.

You crane your neck to see whether they've headed to the back of the exhibit when suddenly a deafening roar cracks out from among the rocks--deafening not because it's loud, though it is, but because the roar of the tiger is so primally terrifying it causes your blood to freeze and leaves you barely able to stand. "Tigers are keen on picking up differences between individuals," zookeeper Ross Taylor will explain later. "They depend on their physical abilities and powers of observation to survive."

In the same way tigers in the wild test their prey before pouncing, these little princes have been sizing you up--carefully calculating your line of sight, then hiding just out of view to determine your reaction. And the fact that they don't look playful, or angry, or anything except very coolly interested makes the behavior all the more terrifying. Those bright eyes, you realize, are taking you in with the same unself-conscious, hungry impatience you might assume while waiting for the toast to be done.

Which may be why the tigers at the Minnesota Zoo are among only a few hundred left of their breed. It's been 150-odd years since reliable, accurate guns leapfrogged humans ahead of tigers in carnivorous superiority, and we've made strikingly effective use of that power. Think of us as well-armed, vengeful deer.

At the turn of the century, 100,000 wild tigers roamed a range from the Siberian tundra to Indonesia to Turkey. Today there are probably 7,500, and three of what were once eight tiger subspecies have disappeared from the face of the earth. If, as the World Wildlife Fund predicts, within a decade "the only tigers left in the world may be those kept in zoos," we will lose one of the few remaining natural reminders that people are not as evolutionarily superior as we like to think.

If, on the other hand, the wild tiger survives, it may be precisely, and ironically, because some of its kin were kept in zoos--and because of the decision by some of those institutions, including Minnesota's, not to settle for captivity as the tiger's future.

The Apple Valley institution has had "a commitment to tigers" since it opened 20 years ago, says CEO Kathryn Roberts; witness the outdoor exhibit, home to six Siberian tiger males and two females. But popular as the carefully designed mini-habitat may be, it's only the visible tip of an iceberg: The zoo's real tiger business is conducted far from visitors' view. In a series of buildings at the compound's eastern edge, zoo Director of Conservation Ron Tilson marshals a staff of colleagues and graduate students who make up one of the most powerful forces in tiger conservation today.

"For the longest time we have been referred to as the 'Minnesota Mafia,'" says Tilson, "because the tiger anchor is set here. We at the Minnesota Zoo developed the [world tiger conservation] program, we have maintained the program, and we coordinate it to this day."

Tilson is a warm, easy-going man with the sort of pacific confidence associated more with retired surfers than biologists. His office is filled with popular images of tigers--posters showing tigers leaping out of gas pumps, wildlife-magazine covers with tigers staring coolly from their rocky perches. (Globus, one of the three young males at the zoo, made the cover of National Geographic.)

Tilson has been living and breathing tigers--literally--for 14 years. He has immobilized them for medical reasons, supervised their mating, and helped deliver their cubs; he's even dug through their insides during autopsies. Tilson has been as intimate with tigers as people can get, and for his troubles he now gets hives: "I don't pursue personal relationships with tigers," he says, "because I've handled tigers so many times over the years that I'm now allergic to them. If I so much as touch one, I break right out."  

Not that it matters much: These days, Tilson's work has more to do with databases, international meeting rooms, and high-tech research equipment than with animals in the flesh. He is the founder and head of the Tiger Global Conservation Strategy, an umbrella program that coordinates all the scientific tiger-management efforts in the world. He also supervises the Sumatran Tiger Project, an endeavor uniting the Minnesota Zoo and Indonesian conservationists to save an entire subspecies of tigers. Finally, he heads the tiger portion of the Global Animal Survival Plan, an international strategy that coordinates zoo programs with nonzoo activities. The man has a résumé that reads like the phone book, representing a lifetime of work for and with tigers.

Tilson came to the great cats by way of a long-term love affair with Southeast Asia. In the '60s he served a stint as a Peace Corps volunteer in Malaysia; later he worked as a field biologist studying gibbons on the remote Indonesian island of Siberut. (He still sports the gibbon tattoo he acquired to convince the island's residents that he was serious about his work.)

In 1984 Tilson came to the Minnesota Zoo to work with Ulysses S. Seal, one of the zoo's founders and an international authority on the management of endangered wildlife. When Seal stepped down eight years ago, Tilson assumed his mantle as the world's foremost zoo-based tiger conservationist. Today he spends half his time in the field in Indonesia, raises funds all over the globe, and finds that tigers are "all-consuming. I do nothing but tigers. If I could clone myself, I would."

To get a sense of Tilson's stature in the tiger-conservation movement, consider this: No zoo tigers in the world mate without his go-ahead. And that's bad news for Zara, a Siberian female at the Minnesota Zoo. In the throes of estrus (heat) recently, Zara was madly, desperately friendly. She rubbed her face on the bars of the cage where she was being kept away from the males, a submissive house-cat look in her eyes. She swung her big head around like a drunk woman with a glamorous shock of hair. She made the quiet chuffing noises tigers use as an amicable greeting to anyone who walked by. She rolled around on the ground like someone with a saturating itch.

Zara, mother of two litters, won't mate this year because there isn't room in North American zoos for more tigers. Only about eight or nine cubs are needed every year to replenish the captive population, so most fertile tigers are kept alone or on birth control. But Zara is lucky: Unlike most zoo tigers she will mate several times in her lifetime, constituting as she does a precious contribution to the captive-tiger gene pool. As early as next year, zookeepers plan to join her with her Minnesota Zoo neighbor and fellow Russian émigré Globus.

To tiger breeders, Zara and Globus are a match made in heaven because both were born in the tundra, among the 400-some wild Siberian tigers left in the world. Zara's mother was killed by poachers when she and her brother were cubs; since they lacked the resources to survive on their own, researchers installed them in Russian zoos, which sent them--via Calgary, where Zara's brother lives--to Minnesota. Globus's mother lost her own mother to poachers before she could teach her how to care for a cub; Globus was taken from her after it became clear that he was suffering severe malnutrition. (Poaching is one of the greatest threats to wild tigers: By some estimates a tiger a day is killed to end up as an ingredient in traditional medicines. TRAFFIC, the World Wildlife Fund's wildlife trade monitoring program, recently found that tiger parts were readily available in pharmacies throughout the U.S. and Asia.)

Zara and Globus's wild origins mean that they are probably not related to any of the tigers in the Siberian Tiger Studbook, a database maintained by Kathy Traylor-Holzer, a research biologist at the Minnesota Zoo. When zookeepers at one of the world's scientifically managed institutions want to mate one of their tigers, they send a request to Tilson and Traylor-Holzer, who run the numbers through a complex mathematical formula to calculate how closely related the animal is to all other managed tigers. A committee headed by Tilson and composed of members elected from zoos with tiger programs then tempers the results with a dose of pragmatism: It is hard for tigers to switch climates or travel great distances, so a Boston tiger will be more likely to receive a partner from Philadelphia than one from Miami.  

On the worldwide ranking system used to measure which tigers are least related to any other captive tigers (and thus most likely to be bred), Globus is number 1 out of 61 Siberian males. Zara is number 8 of 48 females. Once their cubs are born, all the rankings will be recalculated to reflect the new kin.

The tiger studbook is part of a series of international efforts to scientifically manage the captive populations of rare and endangered species. Many of the programs are based in Minnesota, including the International Species Information System, a database coordinating the genetic future of some 6,000 rare species at 500 zoological institutions around the world, which is housed in the same building where Traylor-Holzer and Tilson work.

The programs, and the philosophy underlying them, are the legacy of Tilson's mentor, Seal. When he began his work some 20 years ago, zoos frequently bred tigers and other rare species indiscriminately, to preserve a popular animal's legacy or simply for the babies' crowd appeal. Seal, concerned that this was leading to inbreeding and health problems, devised a scientific method designed to maximize genetic difference among animals. As a result, notes Tilson, some captive populations today are more genetically diverse than their wild counterparts. "[Seal] was the architect of the philosophy that is now used in every zoo in the world," he says, "and it was all done with tigers, and it all started here."

Up to now the work of breeding specialists has essentially been that of a matchmaking service--setting up animals for blind dates. But that could change thanks to the efforts of Traylor-Holzer and others working on the next level of rare-species reproduction. For eight years, Traylor-Holzer has been climbing into tiger cages all over the world to collect tiger semen--a process that involves getting uncomfortably close to a sedated male, inserting an electrode-studded probe into his anus and pulsing low voltage so that he eventually ejaculates. (You can see a picture of Traylor-Holzer doing this on the Tiger Information Center, a massive Web site started by Tilson, at

"Here you have a dangerous animal who is sedated, but you're providing a good reason for it to wake up," Traylor-Holzer explains. "It's quite an experience. They extend their legs, vocalize and growl a little. By the time you get into it you're very watchful. You don't want to become nonchalant about their welfare and for your own welfare."

Once collected, the semen, along with tissue samples and blood serum, is frozen in a liquid nitrogen tank and flown to the National Zoo in Washington, where it becomes part of a collection called the "Tiger Genome Resource Bank." Ultimately, researchers hope to use the material for artificial insemination and in-vitro fertilization. The techniques are more difficult to use in tigers than in people or cattle, since females only release ova after several days of mating or hormonal stimulation. But both procedures have succeeded in experiments at the Henry Doorly Zoo in Omaha, and Traylor-Holzer is enthusiastic about their future.

"If you want to get real idealistic about it," she says, "not only can you exchange [genetic material] between Minnesota and Miami, theoretically you could exchange material between captive and wild populations." Right now, mating a wild female with a captive male would mean holding her for one week to three months--the period it takes for tigers to conceive--and during that time she could lose her hard-won land to a rival, Traylor-Holzer explains. "But if we can inseminate her with captive-tiger material, then she would only need to be held for about two or three days, and she won't lose her territory or have any problems."

But if the goal is to add to the wild-tiger population, you might ask, why not just release young tigers, like they did with the lion in Born Free? One reason is that the last thing tiger advocates want is to send ferocious animals who see humans as the bearers of food--or, for that matter, as food--wandering around the landscape. Another reason becomes evident once you spend a few hours at the Minnesota Zoo's tiger barn.

The barn, where the tigers spend their unexhibited time, is essentially a wet jail--a series of 10-by-12-foot concrete-floored cages with spartan sleeping platforms, bright lights, an animal scent like clean, wet dogs, and tiger threats telegraphed from cage to cage with looks, huffs, growls, and snarls. The signals are evidence that domestication hasn't changed the tigers' fundamental preferences: In the wild, these are among the most solitary of animals, requiring enormous private ranges of between 10 and 120 square miles each. Even at the zoo, most adult tigers want nothing so much as to chase the other tigers from what they consider their personal territory. Imagine keeping a dozen medieval warriors, with knives and clubs attached to their bodies, and you'll get an idea of what it's like to keep tigers. Siberian tiger males grow to around 10 feet long and can weigh up to 675 pounds; their jaw muscles are as powerful as our thigh muscles, and their canines are the size of human fingers.  

"We really have to be very careful," says zookeeper Taylor. "The other side of the bars is as close as we come." A few years ago, he recalls, two Minnesota Zoo subadults who had been exhibited together finally decided they were adults and had had enough of sharing territory. Since fences prevented the loser from running away, the bigger tiger bit clear through the smaller one's trachea.

But while zoo tigers retain many of their wild instincts, they have lost the vast majority of their "culturally transmitted" information--the sophisticated survival skills developed over hundreds of years and transmitted among wild tigers from generation to generation. Captive tigers don't know how to butcher animals by removing the colon first, so that the meat will keep better; how to chase jaguars out of their territory or keep crocodiles from eating their food; how to recognize poisonous or dangerous animals; how to pluck birds (tigers don't eat big feathers); and so on. When an unlucky peafowl or woodchuck strays into the Apple Valley exhibit, says Taylor, the tigers will jump it out of instinct. But instead of eating their prey, they'll carry it around like a rag doll or effetely deposit it in a corner. In short, chances are they would not last long in the wild.

Their genes, however, might. Today, free-ranging tigers are more in danger of becoming inbred than those in zoos: Roads and cities traverse more and more of their habitat, creating ever-smaller tiger enclaves whose inhabitants mate only among themselves. Experts hope that if genetic material from zoo animals--including, perhaps, Zara and Globus's future offspring--is injected into those small groups, the result will be healthier populations. In return, the wild tigers will provide the skills Zara and Globus's great-grandchildren will need to survive in a world without regular snacks of horse loaf.

But none of that can happen if those future tigers don't have a place to live. That's why Tilson has moved his focus from breeding zoo tigers to conserving, and possibly expanding, the habitat of their brethren in the wild.

In the early 1990s, Tilson found himself back in Indonesia, working to set up the first in a series of partnerships under his Adopt-a-Park program, which pairs well-off Western zoos with their counterparts in the Third World. The Minnesota Zoo was joining forces with Java's Ujung Kulon, a critical rhino habitat (next time you're in Java, look for the Minnesota, a boat park authorities use to patrol for poachers). But Tilson was thinking tigers: Java's own tiger subspecies had gone extinct just 20 years ago. But on the nearby island of Sumatra, several hundred tigers survived. It was this population, Tilson decided, that would become his most ambitious project yet.

The Sumatran tiger isn't as big as its Siberian cousin; its fur is a brighter orange, and its range tends to be smaller because of a denser prey population. Its favorite food are wild pigs, deer, and monkeys. And while tigers in preserves elsewhere in the world have become accustomed to people, the Sumatran does its best to avoid humans: "About the only way you really know when tigers are around is when you see them, which in our case is hardly ever," says Tilson. "Though you do see the tracks, and you often come to places called scrapings where they defecate or urinate--and they urinate a lot."

Tilson set about his project methodically. He raised funds from Western institutions, obtained the many permits required by Indonesia's government, and put together partnerships with Indonesian researchers, park officials, and rangers. The result was a unique program aimed at serving both Sumatra's tigers and their human neighbors.

"There are three ways of dealing with tiger conservation," says Tilson. "One is just understanding what their needs are, which is a biological question, and we've pretty much got that figured out. The second is protecting them from poachers; that's been worked out by the people in rhino conservation." (Since poachers only earn a fraction of the market price of endangered-species parts, frequent patrols deter them, Tilson says: Their prey may be valuable, but it's not worth risking extreme hardship.) "The third one, and this is the toughest, is building a sense of harmony between people and tigers when they share the same resources."  

The Sumatran Tiger Project currently has two main parts. One is a detailed exploration of the needs of the people living in tiger habitats to determine what they need to exist in reasonable harmony with the animals. Findings so far, Tilson says, suggest that "there is already a conservation ethic among the people who live there. They value wildlife, they understand its relationship to their cultural and biological heritage, and they don't want to see it all gone."

Ultimately, Tilson and other researchers envision a partnership between local residents and wildlife. Philip Nyhus, a St. Olaf College instructor and the community conservation coordinator of the Sumatran Tiger Project, cites a recent case in which the Minnesota Zoo Foundation, through the Adopt-a-Park program, worked with Sumatran villagers looking to keep elephants from a park out of their farm fields. In return for funding to complete a ditch, Nyhus says, the residents "agreed to try to help reduce the amount of people going into the park illegally to collect wood and grass, or fish and hunt." Nyhus says it's that kind of cooperation that could ultimately create a sustainable habitat for both people and tigers.

The other part to Tilson's project--a detailed census of Sumatran tigers--is proving trickier. For the past two and a half years, a team under his supervision has been rigging the island's forests with cameras that work like burglar alarms, automatically snapping time-coded pictures when a large animal breaks an infrared beam. In one area, the researchers have become so familiar with the local tigers they have assigned names to some 30 of them; they can tell them apart, Tilson says, because of the patterns of their stripes, each as unique as a fingerprint.

Having surveyed more than half the Sumatran habitat, the team now estimates that there are some 450 wild tigers on the island. "In another year we will know all of the habitat," says Tilson. "We will know how many tigers are in those areas, and then we can ask: How many tigers do we need for the future? We need about 1,000 to 2,000 tigers living naturally, so we simply look at a map and draw lines and add up until we get to 1,000 tigers.

"Then we figure out that that's where we're going to fight the war. It might be that you say: 'You know, we don't even have 1,000 tigers, we actually only have 500. So we need to create more habitat.'" This is the critical moment where Ron Tilson, to quote from the motivational-speaker vocabulary, "breaks the box" and redefines a paradigm. "Most people in conservation, including me, are kind of in this rut," he says. "You just talk about what needs to be found out, and you're always in this 'We need more information' mode. I call this defining the problem. Conservationists can talk 'til the cows come home about defining the problem, but they can't step beyond that once they have defined them. And that is what I am starting to come to grips with. How do we solve the problem, period?"

Tilson's answer has a pleasant practicality to it: Just buy a lot of jungle and give it to the tigers. He began to view matters that simply, he says, during a conversation with a would-be financial angel, whose name and affiliation he refuses to divulge. "[He] came to me and said, 'I want to make a business proposition to you. How much will it take to secure the future of the Sumatran tiger? Just tell me how much money it would take.' I said, 'I think it would probably cost you about $20 million dollars, and maybe up to $40 million.' And he said, 'Okay, I can raise that, but there's one caveat: You can't fail. So tell me how you're going to do it.'"

The secret angel has yet to cough up the $40 million, but Tilson--dizzy with the fundraising successes of the past several years--speaks about the possibility of a Sumatran tiger renaissance with a real fire in his eyes. He's raised around $1.6 million for the project from U.S. sources so far, not counting $6 million pledged by Exxon over a five-year period that began last year. And while that might not seem like much, it's incredibly successful in the penny-pinching world of conservation. "A few years ago when we got a grant for $15,000, we were absolutely thrilled," says Traylor-Holzer. "Now [Tilson] just got half a million in the last month or two."

As for the reality of creating a vast tiger preserve in Sumatra, Tilson says that's the easy part: The island, he says, is full of cheap oil-palm plantations that could be converted back to jungle in almost no time. "The very forest we're working in is a biological experiment," he explains. "It was completely logged 18 years ago, and now it has one of the densest populations of tigers anywhere. It's diverse, abundant, vibrant. So I know that we can create habitat very quickly in the tropics. Maybe some people would say 10, 15 years is too far down the road. But I'm trying to take the approach that Dr. Seal taught me: You don't plan for your lifetime, you plan for several lifetimes ahead, for your children's children."  

The genius of Tilson's vision, some of his fellow experts say, lies in using the tiger as the flagship animal for what is actually a far-reaching conservation campaign: Because tigers need a vast, undisturbed habitat, what's good for them is also good for other endangered species such as the sun bear, the clouded leopard, and the Malayan tapir (a piglike animal with a long, trunklike nose)--not to mention plants, fungi, microbes, and many other unglamorous species equally vulnerable to habitat destruction.

"People want to save a tiger," because of its cultural charisma, says Rich Block, vice president of Scientific and Program Development at the Indianapolis Zoo and a former WWF senior fellow. "But Ron has used the tiger to frame a conservation issue--what he's really doing is having an impact on the habitat. The tiger [provides] something that people can rally around, to see how you can protect the integrity of the place where these animals come from. Remember Clinton's mantra, 'It's the economy, stupid'? For all of us working in conservation, it's 'It's the habitat, stupid.'"

Of course, for every slogan there's a counter-slogan, and conservation campaigns can get just as heated as election battles. "There are folk who want to say the tigers will be gone in another couple years, the wildlife will be gone, blah blah blah," Tilson says. "That is something that is said a lot, and there are a couple of major organizations that use those kind of tactics for fundraising." Though Tilson doesn't name names, he might well be referring to groups like the World Wildlife Fund, which frequently warns that "within a decade, wild tigers could be totally extinct."

"That [statement] needs to be elaborated," concedes Ginette Hemley, WWF's director of international wildlife policy. "If we don't continue to expand our efforts and stick with long-term commitments; if we drop our guard today; certain populations could go extinct." The fund, Hemley says, now aims chiefly to reduce the demand for traditional medicines made from tiger parts. "The work that Ron is doing is a critical piece of the whole picture," Hemley says. "But we cannot just focus on habitat conservation alone."

Tilson, for his part, disagrees with the WWF's and other groups' focus on Asian medicinal practices, which he says are overrated as a cause of tiger deaths. In any event, he insists, hand-wringing is counterproductive when there is a real chance of saving the tiger: "In Sumatra alone, if they have 1,000 to 2,000 wild tigers, that is going to be more than enough to exist indefinitely in a healthy situation. Most wildlife managers will tell you we don't need to worry genetically or demographically with these kind of numbers. And I believe we have the capability of determining where they are, protecting them and securing them for the future. It just takes a lot of work. And that's what I do."

Skeptics will note that even if Tilson is entirely successful, he will help assure the future of only one of the world's remaining five tiger subspecies. Tigers on the rest of the planet still live in a tangle of poverty-ridden populations and politically unstable governments--Myanmar (Burma), Cambodia, North and South Korea, Vietnam, Laos, Thailand, China, India, Bangladesh, Nepal, Bhutan, and Russia, all places where development pressure and economic desperation combine to make tiger preservation a secondary matter. Even Tilson concedes that lasting tiger preservation across all of the former tiger range is probably unlikely.

Instead, some tiger species may incur the fate of the South China tiger, which for the last 20 years has been seen only in zoos. (Just 40 years ago there were probably more than 4,000 South China tigers in the wild, but the Chinese government declared them pests and encouraged their slaughter.) On the other hand, tigers have surprised us before. Maybe a few South China tigers are still prowling their territory, to re-emerge suddenly one day--just as the wapiti, a kind of red deer thought to have been extinct since the 1950s, reappeared two years ago in a remote part of Tibet. Whether hiding deep in the forest or surveying you from a placid zoo exhibit, tigers remain enigmatic. Even Ron Tilson, who has spent the better part of 10 years camped out in tiger habitat, doesn't know all there is to know about them. And he's never seen a Sumatran tiger in the wild.  

"That's the oddest part of this whole study," Tilson acknowledges. "In [Sumatra's Way Kambas] national park I have 12 people working in the field all the time. Every three days we walk 162 kilometers, to check the cameras--to change the film, change the batteries, make sure everything's proper. In this entire amount of time we have never seen a tiger in the field.

"We see their tracks. We see their urine and their scrapings. We see the dead animals that they've killed--and we don't see the tigers. We even have photographs of these tigers where we've set up a camera and the staff is there, we take a photo, and because it's time-coded, [it's clear that] sometimes within 10 or 15 minutes the tiger comes and photographs himself, urinates on the camera, and then walks away. So here I am, a recognized world authority on the Sumatran tiger, and I've never seen the damn thing.

"And I've almost gotten to the point where I prefer not to see one," Tilson says, sprawling in the chair at his Minnesota Zoo office and staring at the ceiling. "First, I don't want to be disappointed. And I know when we do see one it will scare the bejeezus out of us."

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