Beijing resident Wan Yongqing was pleasantly surprised to see a restored panda base on 150-hectares in the Wolong National Nature Reserve in Sichuan province in late April－at the China Conservation and Research Center for the Giant Panda.

As a volunteer, he had visited the center and seen the devastation after the magnitude-8 Wenchuan earthquake on May 12, 2008.

"It was such a mess that I did not believe it could be rebuilt," he said. "But now it's home to the largest number of captive pandas in the world, and it releases them into the wild to enlarge the wild panda population," he said.

Tang Chunxiang, a senior researcher, recalled that one panda died in the earthquake and six were missing.

"One of the pandas, a 9-year-old mother of three cubs, was found dead. And one of the six missing pandas was never recovered," Tang said.

The pandas that survived the quake were terrified and became restless, he said. They tried to escape whenever there was any noise. A keeper had to accompany each panda, caressing and talking with it softly.

Two months later, the pandas were no longer afraid. Most of the pandas from the center's base in Wolong were transferred to the Bifengxia base in Ya'an, Sichuan, and to zoos in different parts of the country, including Beijing.

After the quake, the Hong Kong Special Administrative Region offered financial aid of more than 1.4 billion yuan ($220 million) for the reconstruction of the center and surrounding villages.

The money was used by the center to build a successful new panda base on 150 hectares. Nineteen cubs were born last year, and more are expected this year, said Li Guo, a base official.

In the wake of the 2008 quake, the center released eight captive pandas into the wild. One died, but the others are faring well, according to observations made possible by the GPS tags that hang around their necks.

Tao Tao, a male panda, was 2 years old when released in 2012. He has lived in the wild for six years.

The center made a major breakthrough in improving the genetic diversity of captive pandas when the first cub produced by mating a female raised in captivity with a wild male was born in August.

Cao Cao, the mother, was 16 when released into the wild at the center's Hetaoping base in March last year in time for the panda mating season, which runs from March to May.

At the center's Dujiangyan base, visitors can see keepers caring for pandas which, in terms of human age, would be 70 to 80.

"One year for a panda equals about three or four human years," said Li Desheng, a senior researcher.

After the quake, the center chose a site near Mount Qingcheng in Dujiangyan, Sichuan, to build the world's largest panda disease prevention and control center. The facility, which was also financed by the government of Hong Kong, oversees the activities of captive pandas and provides care for those brought in from the wild.

"The center also serves as a home at which some 10 elderly pandas can spend the rest of their lives," Li said.

Construction of the Dujiangyan center started in September 2011, and the facility began operations in March 2013.

Before 2008, the China Conservation and Research Center for the Giant Panda was home to about 100 pandas. Now, it has 270 captive pandas, accounting for nearly 60 percent of the global total. In addition, 34 of the center's pandas have been loaned to 15 zoos in 13 countries where they are the subjects of scientific research.