BioEd Online

Chinese officials confirmed this week that they intend to continue releasing captive-bred pandas into the wild, despite the tragic death of the programme's pilot panda earlier this year.

Not all scientists agree that reintroduction of captive-bred pandas is a good idea. Even those who support reintroduction admit it will be extremely difficult and may only succeed after years of trial and error. The death of 5-year-old panda Xiang Xiang was tragic, they say, but not unexpected; many more deaths may follow.

"Reintroduction programmes often begin with a high rate of failure, so this isn't unique to the pandas," says Ron Swaisgood, associate director of the Conservation and Research for Endangered Species department of the Zoological Society of San Diego, California. "I don't think there's ever been a reintroduction programme that didn't have mortality."

Pandas in China are severely threatened, largely due to human development of their forest habitats. So the Chinese government set up a programme to breed pandas in captivity. It now has more than 200 pandas, according to David Wildt of the Conservation and Research Center of the Smithsonian National Zoological Park in Front Royal, Virginia.

The Chinese government is keen to release these captive-bred pandas into the wild to try to bolster fragile wild populations. Scientists and animal trainers at Wolong Giant Panda Research Center in Sichuan Province spent three years habituating Xiang Xiang to natural habitats, where he learned to forage for food and build a home. In April 2006, they turned the panda loose in the Sichuan forests; this February, he was found dead. Chinese scientists say that he had been attacked by other pandas, and may have died while trying to run away.

On 12 June, a scientist from the China Giant Panda Protection and Research Centre said that the organization is considering releasing a female panda next — perhaps even a pregnant panda, or a mother and cub. This might be more successful, because females are not perceived as threats, unlike males, which must compete with other males for access to females, the scientist said.

Girl power

Other researchers agree that females would be less likely to be attacked. And a reintroduced cub would have the best chance of surviving if it had been born to its captive mother in a large pen that mimicked natural conditions, says Swaisgood: the cub would then be less dependent on humans than other captive-bred pandas. "I think the earlier you can start to expose a panda to natural conditions, the better the opportunity for natural learning to take place," he says.

Not everyone agrees that the reintroduction programme is a good idea. Sybille Klenzendorf of the conservation group WWF in Washington DC argues that captive-breeding programmes are very expensive, and that the money is better spent conserving wild habitats. There are about 1,600 pandas in the wild, and the Chinese government has protected about 60% of their remaining habitat, he says. It could protect more, Klenzendorf suggests.

"Reintroduction is very expensive, and that money could be used better in wild panda conservation," Klenzendorf says. "If you protect the habitat and stem poaching, you're fine."

Wildt counters that wild pandas do not breed quickly enough to keep a healthy population, so it's necessary to pursue both breeding and wild conservation strategies.

"The population is so fragmented that they are not self-sustaining in the wild," says Wildt. "This isn't a competition — you need to focus on giant pandas in the wild, but at the same time the Chinese realize that there is value in these captive populations, as an insurance policy and as a scientific resource."