今年9月7日，《科学》杂志的《野生生物》（WILDLIFEBI-OLOGY）专栏刊登了题为《野生老虎还能生存么？》
以下是原文, 供参考
Can the Wild Tiger Survive?
Virginia Morell*

China is pushing to reintroduce wild tigers, but critics say its breeding centers offer the tiger only a more roundabout path to extinction

HARBIN, HEILONGJIANG PROVINCE, CHINA--For Xu Yan Chun, a wildlife geneticist at the Northeast Forestry University here, the eight Siberian, or Amur, tigers clustered in the dirt under a shade tree are a sign of hope. Although confined to a shrubby enclosure at the Heilongjiang Siberian Tiger Park in Harbin, the tigers may one day be used to help bring back what China has virtually lost: tigers in the wild. "It's the dream," says Xu, who is analyzing the genetics of the park's 800 tigers to determine how inbred they have become since the government-owned park was founded 21 years ago. He estimates that about 200 of the cats are genetically healthy enough to be used for such a captive breeding program.
Reintroducing captive tigers to the wild may seem a desperate plan. But the plight of wild tigers is indeed desperate. Just 100 years ago, an estimated 100,000 tigers representing nine subspecies roamed Asia from China to Turkey. Today, after almost unrelenting human persecution, fewer than 3000 tigers remain in the wild, according to a 2006 International Union for the Conservation of Nature and Natural Resources report. Their territory has dwindled as well, with tigers inhabiting a mere 7% of their historic range, according to leading tiger research groups. Not more than 50 wild tigers remain in China, says its State Forestry Administration (SFA).

Captive tigers, on the other hand, are booming. At least 11,000 tigers of mixed ancestry are behind bars, estimates Ron Tilson, director of conservation at the Minnesota Zoo in Apple Valley. About 1000 dwell in public zoos in Europe, Japan, North America, and other countries. Astonishingly, more than 5000 tigers are in the hands of private owners in North America. And at least another 5000 live in state and private tiger-breeding centers (or "farms," as many conservationists call them), mostly in China.

So in the late 1990s, when SFA officials began exploring the idea of restoring China's tigers--animals of symbolic and cultural importance to the nation--they turned in part to the tiger-breeding centers. But they are also considering other means, such as translocations of wild tigers or, if feasible, simply encouraging tiger populations to rebound on their own. "The Chinese desperately want to bring back their wild tigers," says Tilson.
But tiger reintroduction is challenging, requiring a genetically diverse population and an estimated minimum of 100 prey-packed square kilometers per tiger--not to mention the need to reacquaint captive animals with the rules of the wild. Tilson himself prefers to avoid using captive cats and is working with Chinese officials to restore the South China tiger (the most endangered of China's four subspecies) by perhaps using wild tigers of a closely related subspecies.

Indeed, for some scientists and conservationists, the captive tigers at China's five commercial breeding centers represent their worst nightmare. They argue that captive-bred tigers, often too genetically similar or hybrids, can never be released, and that unless destroyed they will be used to reignite the trade in tiger parts, which has dropped dramatically since the Chinese enacted a domestic ban in 1993. "The purpose of the tiger farms always has been and continues to be solely for commercial purposes, to sell tiger-bone medicine and wine," charges Grace Ge Gabriel of the International Fund for Animal Welfare (IFAW), headquartered in Yarmouth Port, Massachusetts. "And if they're allowed to" sell these products, "it will mean the end of tigers in the wild everywhere."

Tiger-bone medicine
Tigers, with their lustrous, striped furs and powerfully muscled bodies, have long been seen as embodying magical powers. For at least 1500 years, traditional medical practitioners throughout Asia have prescribed remedies using tiger bone to treat a variety of ailments from rheumatism to impotence. But in the 20th century, the tiger-bone trade increased exponentially, as did sport hunting, deforestation, and other pressures.

To stop the slaughter, in 1975 the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) banned the international trade in tigers and tiger parts. In 1993, China--often the prime destination for tigers poached elsewhere--followed this up with its own domestic ban. Yet even with China adhering to both bans, wild tigers have continued to decline in most of the 14 countries that harbor a population, largely because of shrinking habitat, lack of law enforcement, and a renewed trade in tiger skins.

The Siberian Tiger Park--China's first--was born in 1986 when a wildlife biologist decided to breed captive tigers as a source of tiger-bone medicine, with the hope of decreasing poaching pressure on the wild cats. But before any captive tiger bone parts made it to the market, China banned the trade. Struggling, this center and others turned to tourists and to selling tigers to zoos for income.

At the most recent CITES meeting in June 2007 (Science, 22 June, p. 1678), the centers came under fire when Ireland floated a proposal to study expanding traded items derived from captive wildlife. Several environmental organizations warned that any such expansion would be harmful to wild tigers. In response, China argued that sales from the centers could provide needed funds for conserving its few wild tigers and supporting tiger reintroduction.

Nearly every other state that has wild tiger populations and numerous environmental groups roared in protest, reiterating that such a move would doom the few remaining wild tigers by rekindling the market for tiger parts. They also called on China to close the tiger-breeding centers. "China's ban has done so much to save the tiger," says Judy Mills of the Washington, D.C.-based International Tiger Coalition. "But trade of any kind from any source and for any reason threatens its survival. Nor is there any need to reintroduce tigers. They breed like house cats and will come back on their own if they're protected from poachers."

In the end, China joined the other delegations at CITES and passed a resolution that says the captive breeding of tigers should be restricted "only to conserving wild tigers" and that the felines should not be "bred for their parts and derivatives."

Nevertheless, China has not stepped back from an internal debate about whether to allow its citizens to resume using tiger-bone medicine, although most traditional medicine practitioners argue that alternatives exist and are not requesting tiger bone. (Indeed, last May, the state-owned Tanggula Pharmaceutical Co. in Beijing published a study claiming that mole rat bones were as effective as tiger bones for treating rheumatism.) Still, some of the tiger-breeding centers sell tiger-shaped bottles containing a brew made by steeping feline carcasses in rice wine for several years, says IFAW's Gabriel. SFA officials say that the wine is made with lion bone. One center's restaurant also sold what it claimed was tiger meat as recently as last year, Gabriel adds. And the centers have hundreds of containers of tiger carcasses, skins, bones, and organs in cold storage. "They are valuable, and we hope to use them one day," says Wang Li Gang, general manager at the Siberian Tiger Park. "I'm old enough now that I myself would like to use the tiger-bone medicine."

All this creates pressure to lift China's domestic ban on the tiger-bone trade. "Since 2004, we've received many petitions … to allow the use of tiger bone for medicines," explains Wang Weisheng, director of the Wildlife Management Division of SFA in Beijing. In 2005, SFA began researching captive-tiger breeding and the medical use of tiger bone to assess their "scientific basis," says Wang during an interview in his office. "There must be a benefit to the wild tiger from the medical use of tiger bone using captive tigers" for the ban to be lifted, he says. SFA has gathered expert input through two international tours and a workshop, he says, acknowledging that the conflict between the two positions "is very strong." He says the agency will try "to find a solution" after scientific analysis of the data.

Wang insists that the proposal is not to "reopen the tiger trade." Rather, he says, "if our government approves the use of tiger bone from captive-bred tigers, patients will only be able to buy tiger-bone medicine at designated hospitals." The regulated use of such medicines might dry up the remaining black market, he says, citing a survey by researchers at China's Science and Technology Institute in Beijing.

Dreams of return
Even as the tiger parks push to sell tiger products, they insist that they can also help save tigers by breeding them. Indeed, the most controversial tiger reintroduction plan, called Save China's Tigers, involves using South China tigers from the Chinese Tiger Rewilding and Reintroduction Center in Meihuashan, Hunan Province--and building up stock on a reserve in South Africa, where no wild tiger has ever stalked. Started by Li Quan, a London-based businesswoman, the organization's idea is to "rewild" the captive tigers so that their offspring can survive on their own. With the approval of China's SFA, Save China's Tigers relocated two male and two female tigers in 2003 and 2004 to the South African site. They chose South Africa because "it's very hard to find enough space and prey in China," Li explains
Many tiger-conservation organizations remain highly critical of the plan. "It's a waste of time and money and not beneficial to the species," says Mills of the International Tiger Coalition. "It could even be dangerous, since there are questions about the genetic integrity of the captive cats," meaning that many captive tigers are hybrids of two or more subspecies. "It's better to put all our efforts into tigers that already exist in the wild."
Li says she's "been maliciously attacked for this idea by everyone, but you have to expect that with a new idea." Project manager Peter Openshaw notes that "we do not 'teach' or 'train' the tigers to hunt. … We set up situations whereby they teach themselves to hunt using their natural instincts." And it works, he says. After feeding the tigers antelope carcasses, he released three live South African antelope, or blesboks, into the male tigers' "camp." Instantly, the two tigers chased the antelope "at top speed," catching and killing first one then the other two. Most days, the tigers are fed meat; but about once a week they're allowed to hunt an antelope "to keep up their skills," says Openshaw.

The tigers will have no trouble switching prey from South African antelope to Chinese deer, predicts Gary Koehler, a carnivore biologist with Washington state's Department of Fish and Wildlife and one of Li's scientific advisers. Eventually, perhaps by next year, Li hopes the females will teach their offspring to hunt. These as-yet-unborn tigers, or perhaps the offspring of the offspring, may one day live free on a 200-square-kilometer reserve in Hunan that Li's organization and SFA plan to restore.

But other biologists worry that even if Save China's Tigers succeeds in placing a healthy, hunting tiger in that reserve, it won't be enough space, because a breeding population of 10 tigers is estimated to need at least 1000 square kilometers. SFA's Wang counters that if the reintroduction is successful, more habitat will be found. The plight of the South China tiger makes the unorthodox plan worth trying, he and other supporters insist. "If we do nothing for the South China tiger, we will lose it, so we need to be creative," says Wang.

Other reintroduction projects are under way, too, but these skirt the problem of "re-wilding" by relying on existing populations of wild tigers, even if they are from a different subspecies. For example, Tilson is working with SFA on a project to restore the South China tiger perhaps by using its close cousin, the Indochina tiger. Between 1000 and 1200 of these tigers are thought to live in scattered populations in China, Laos, Cambodia, Thailand, Vietnam, and Myanmar. "Morphologically and genetically, you really can't tell them apart," says Tilson, adding that the subspecies differences are "biopolitical differences. The historical designations are there only because there is a border." The tigers would be given a 1000-square-kilometer preserve straddling Hunan and Hubei provinces.

Tilson's proposal with SFA calls for converting the existing pine and fir trees ("You can't really call it a forest, since the trees are planted like rows of corn, and there's not a weed or bird or mammal in sight," he says) to the original habitat of shrubby grassland, then building up populations of native deer and boar, the tiger's preferred entráes. Once habitat and prey are restored, and villagers (Han Chinese intellectuals who fled here during the Cultural Revolution) relocated, Indochina tigers would be brought in from another as-yet-unidentified population, probably young tigers leaving their mother's territory. "They will do just fine," Tilson predicts. He hopes that the project will eventually "give China and other countries a model that can be used elsewhere."

Meanwhile, in Yunnan Province near Laos, James L. David Smith, a wildlife biologist from the University of Minnesota, St. Paul, and Zhang Li, a wildlife biologist at Beijing's Normal University, are working to bring back the Indochina tiger itself; no more than 16 are thought to live in China. Still, "there are three reserves that potentially have populations," says Smith, who with Zhang and Yunnan's forestry department has launched an in-depth survey. In April, one of Zhang's students photographed an Indochina tiger inside one of the reserves (see photo). If the team finds a breeding population in China, Smith suggests that the Chinese follow his plan for Nepal, where he encouraged the government to work with local communities to protect the tiger. "There are now more tigers in Nepal [about 120] than when I did my Ph.D. research in the 1970s and '80s," he says, largely because of increased mixed forest cover. "That is the key: good tiger habitat."

Back in Beijing, Wang hasn't given up on captive tigers. If the Save China's Tigers project succeeds, he says he might consider a reintroduction program for the Siberian tiger, too, using some of the genetically healthy captive Siberian tigers Xu has identified at the Siberian tiger-breeding center. But that remains only an idea. For now, these Siberian tigers will remain in captivity, entertaining tourists on the Number One Adventure Bus, chasing chunks of raw meat, mating with their close relatives, living, as most tigers do these days, behind bars; their fate after death uncertain.