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Zhang Hemin |
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An estimated 1,500 wild pandas are left in China, where they live in small colonies scattered over six inland mountain regions.
"The geographic barrier is forming an isolating mechanism that poses considerable threat to the continuity of the endangered species," Zhang said. "So we are exploring a way to avoid inbreeding of pandas."
"We" is a team of scientists at China's premier panda research center—Sichuan province's Wolong National Nature Reserve. Zhang, director of the reserve since 2002, has led the team to breakthroughs in giant panda breeding and feeding techniques since the early 1990s.
For the last several years, the team has been training captive pandas in preparation for release on the reserve, which is home to one-tenth of China's wild pandas.
But the venture is not without risk. Despite three years of training, the research center's first captive panda died within less than a year of its release.
Everything went smoothly for five-year-old Xiangxiang, released in May 2006, until one cold December day. Suddenly, signals from his Global Positioning System device indicated that he was moving quickly over a long distance. When researchers spotted him several days later, they found his hind legs covered in wounds—marks from a fight with wild male pandas.
After treatment, researchers re-released Xiangxiang at the end of December. Two months later, they found him dead in the snow. Autopsy results showed that the bear had fallen to his death in another fight with the wild pandas.
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Zhang Hemin |
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"The sacrifice was distressing, but worthwhile, considering what we discovered through it," Zhang said. "Our study affirmed an old and untested theory that a colony of pandas would only accept female strangers."
That theory has set the stage for the next phase in the experiment—releasing captive females. According to Zhang, researchers will intensify training in fighting and survival skills before they release the females into less populated areas of the reserve.
Researchers don't anticipate a repeat of what happened to Xiangxiang. But dealing with that kind of loss is nothing new for Zhang, who has been observing pandas since he was a student of zoology at Sichuan University in the early 1980s.
After earning his master's degree with a focus in population dynamics from the University of Iowa, Zhang returned to China, where the population of wild pandas had dropped to just above 1,000 when he went back in 1989.
Zhang plunged into research on panda feeding habits and propagation, overturning concepts about panda living conditions (they were happiest living in isolation) and diet (they preferred eating only bamboo) that had been in place since the late 1930s.
But the center's biggest breakthrough came in 1991, when it saw the birth of its first panda in captivity with the help of the new methods. That was followed by the birth of twins in 1992. Researchers, government officials and average Chinese were overjoyed with the news.
So when the infant panda died six months later, it was a hard blow to Zhang and his colleagues. When it happened, they could do nothing but cradle the panda's tiny body and cry.
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Zhang Hemin |
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"None of us had thought it would die. We had believed it a success. It was the most painful moment in my life," Zhang said. But the pain spurred him on.
In 2000, Zhang's team finally perfected its system for artificial breeding in pandas—a combination of hormone induction and stress mitigation techniques that took into account everything from the pandas' diets and living conditions to a reproductive phenomenon known as delayed implantation.
With delayed implantation, giant pandas' fertilized eggs float free in the uterus until summer, when the eggs attach to the uterine wall and begin to develop. No one knows the specific environmental conditions that trigger implantation, but actual pregnancy can be as short as 70 days or as long as 324 days.
That is one more x-factor determining the future of a species known for its high rates of infertility and threatened by large-scale habitat degradation.
Most of China's pandas—about 70 percent—live in reserves scattered throughout Sichuan, Gansu and Shaanxi provinces. The 60 reserves in those provinces cover nearly 50 percent of the species' habitat, but are often disconnected from other panda reserves. Connecting and expanding these reserves is one of Zhang's major goals.
He sees opportunity in the 2008 Beijing Olympics, which should bring even more international attention to China's animal ambassadors and the reserves in which they live. Zhang estimates that Wolong can accommodate 700,000 tourists a year, nearly 500,000 more than the current 200,000 annual visitors.
To mitigate problems stemming from such a drastic increase in tourism, Zhang said only 5 percent of the reserve will be open to tourists. But that increase will go a long way in helping the region's 4,500 human residents, according to Zhang.
"For the benefit of local development, we do expect more visits during the Olympics next year," he said.
Wu Chong is a freelance journalist who has written for China Daily and SciDev.net. She is also an editor for Global Environmental Review, a Chinese electronic magazine about environmental news.
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English (英文)
Chinese (中文)