In May, the Chengdu base began building a wild training center for captive-bred pandas at Majiagou, of Yutang Town in the city of Dujiangyan City. The 135-hectare area will host 40 to 50 giant pandas raised in captivity for wild training.

In August, a captive-bred giant panda gave birth to a male cub in a near-wild environment in forests of Wolong. Another three pregnant giant pandas are expected to delivery this year.

"The wild training is essential to improving panda's survival skills in the wild environment," said Zhang Zhihe. "If the training proves successful, it will eventually help pandas' restore their wild nature and save the species from extinction."

Under both programs in Chengdu and Wolong, pandas under training are expected to live in the wild on their own, while zoo workers will observe them through surveillance cameras.

If they need help, the workers will show up dressed in costumes that make them look like giant pandas, in order to reduce the animals' reliance on humans.

At the Wolong center, the expectant panda mothers under wild training are expected to give birth in the forest, covering some 20,000 square meters, and will live there until the young pandas are three or four years old.

The Wolong program is the second phase of a plan to gradually release captive-bred giant pandas into the wild.

The first phase of the scheme, launched in 2003, suffered a setback when Xiang Xiang, a 5-year-old male giant panda, was found dead in 2007, 10 months after he was returned to the wild. He had apparently been attacked by wild pandas.

According to Li Desheng, deputy director of the Wolong center, Xiang Xiang's case proved that wild panda communities were very reluctant to accept male outsiders.

Researchers, however, refused to be discouraged by the setback.

"The ultimate goal of panda breeding research is not to raise them in captivity, but to release them to the wild," said Zhang Zhihe.

Giant pandas are the world's most endangered species. About 1,600 live in the wild.