George Schaller, a prominent US wildlife researcher and zoologist, named by Time magazine as one of the "Heroes of the Environment "in 2007, was among the foreign experts stationed at the center.

Schaller and Hu worked together for many years, collecting huge amounts of data on wild pandas, laying a solid foundation for protecting the animals in China.

"Hu contributed greatly to China's huge achievements in giant panda conservation," Schaller said.

Hu shared his experience with Hughes at his home in Nanchong city, Sichuan. "Research conditions were rather tough at that time. All we had were our legs and a pair of binoculars," Hu said.

In 1980, after hearing that a giant panda had died in the forest, Hu rushed to the scene, where he performed an autopsy on the highly decomposed carcass, from which more than 2,000 roundworms were removed. His work resulted in the first detailed record of roundworm infection in the history of giant panda research.

Hughes said: "It was a pretty unhealthy panda. None of the villagers would go anywhere near it, saying it smelled too bad."

After years of collaborative research with WWF, in 1985, Hu and his team completed the world's first comprehensive study on the ecology and habits of the giant panda, titled "The Giant Panda of Wolong."

Hu's life has been full of unforgettable experiences and achievements, but at age 92, he said his greatest regret is that he will not be able to continue his work forever. "I haven't done enough," he added.

Hughes and Hu exchanged stories and spent time going through the panda expert's photo album.

The image that caught Hughes' eye was one from Hu's birthday party celebrations with his students. Hughes spotted a few familiar faces she knew who are now among the leading academicians in China.