BA Si just celebrated her 30th birthday, making her the oldest known giant wild panda and one of the most famous and special. The average life span of a giant wild panda is 12 years; in panda years, age 30 is like 120 years for a human.

Ba Si lives at the Panda World in Fuzhou, capital of Fujian Province on China's east coast and her life is a history of panda science and conservation. Through Ba Si, scientists have learned many things about keeping pandas healthy; she is one of 312 in captivity in China. In 1990, she was chosen as the prototype for Pan Pan, the mascot of the Beijing Asian Games.

Ba Si is also a lucky panda. In the early 1980s, wild arrow bamboo bloomed and died in the panda's habitat in southwest China's Sichuan Province. That species blooms every 60 years; new bamboo takes at least 10 years to grow and become edible for pandas. Thus, pandas were in danger of starvation.

Ba Si was one of them. She was first saved by Li Xingyu, a farmer from Yongfu Village of Baoxing County Sichuan Province. On February 2, 1984, Li was crossing a bridge to collect firewood when she saw a panda struggling in the water. It was stuck between stones and might have slipped into the river when going downhill in search of food.

Li immediately jumped into the freezing water, pulled the panda out and warmed it up. The next day Li sent the panda to the Wolong Giant Panda Protection and Research Center in Sichuan, and she named it Ba Si after Ba Si Creek, where the creature was saved.

"It was my destiny to find her and save her. I know the panda is protected and I should lend a hand," Li recalls.

To preserve the starving pandas, forestry officials started providing more food and relocated most from their mountain habitats to professional breeding centers, where they were fed and bred. But some starving pandas were still in the wild. To prevent such tragedies from happening again, scientists undertook extensive research on how to sustain the species outside their native habitat. Ba Si was moved to the Fuzhou Panda World, one of China's three panda breeding and protection centers.

Chen Yucun, director the panda world, thought the best way to learn about the panda's needs was to tame Ba Si. Taming had proved useful in previous experiments.

"No normal physiological indexes of pandas had been created before our experiment," Chen says. "Previously, relevant indexes were collected when pandas were either ill or tranquilized. They were unable to attack people but the readings were not accurate. With proper training we were able to measure heartbeat, breathing and body temperature without restraining or tranquilizing. This could provide us good references for diagnosing disease in giant pandas."

Ba Si was tamed in two respects: She became familiar with her environment, including temperature, humidity and food. She also became familiar with her keepers and working staff at Panda World.

Pandas' native habitat is the cold and damp bamboo forests in mountains as high as 2,000-3,000 meters. But Fuzhou is just 83 meters above sea level and in summer the temperatures are often above 30 degrees Celsius.

First, Ba Si got a cooler environment in her "house." When temperatures hit 37 or 38 degrees, the staff used electric fans and ice to cool it down, or moved pandas to the cooler basement. At the time air-conditioning was not dependable.

But all these measures proved unsuccessful. "Finally, we realized that we should take the pandas to a higher elevation, so we found Guling Mountain for the pandas' new residence," Chen says.

Guling Mountain is about 13km from downtown Fuzhou, and 800 meters above the sea level. The average annual temperature is 14.6 to 15.6 degrees Celsius and it rarely gets above 28 degrees in summer. Guling is also covered with dense bamboo.

"The pandas changed a lot, for the better; they put on weight and their coats improved. Life on the mountain was more comfortable and the bamboo was fresh," Chen says.

Though the hot weather was no longer a problem, it was still difficult to monitor Ba Si's physical conditions at close range. Since she was wild, she was always alert and wary of humans and could turn fierce when she felt threatened. At first the staff followed standard procedure, tranquilizing, to give her checkups and treatment.

"Domestication is often thought of as a way to train animals to perform, as in a circus. But that's not correct," says Chen, a member of the Conservation and Breeding Specialist Group. "We domesticate for scientific studies. It may look like a performance when we approach Ba Si and shake hands with her, but actually we feel her palm's temperature to learn whether she had a fever. If we always relied on tranquilizers, it would do a lot of harm to the animals."

Despite objections of specialists in his group, Chen began his domestication plan. Every morning, panda feeder Shi Feining trained Ba Si to urinate in a fixed place, to run, balance and walk upright. "Ba Si was very smart and learnt fast, but some other pandas never understood," Shi says.

As she trained every day, Ba Si gradually overcome asthma, anorexia and her dislike of exercise. She became stronger and after a few years she was no longer afraid of humans.

"After moving from the wild to man-made homes, pandas did not need to forage for food and could spend all their time between meals sleeping. So it was essential to find them something to do to build up their bodies," Chen says. "Training has also enabled us to measure her heartbeat and temperature at any time. It's quite important for health."

Ba Si even learned to walk upright and shoot baskets. In 1987, the San Diego Zoo invited her for shows. During the six months, she was known as the "Stunt Panda."

After she returned from the US, the Beijing Asian Games organizing committee invited Ba Si to perform in Beijing, and later used her as the prototype for Pan Pan, the mascot for the 1990 Beijing Asian Games. Ba Si became a part of the whole country's image.

"Ba Si was then active, energetic and quite cooperative. She could perfectly represent our mascot Pan Pan," says Liu Zhongren, designer of the mascot of 1990 Beijing Asian Games.

Ba Si rose to fame. After the Beijing Asian Games, she was invited to tour around China. No panda had ever drawn so much attention and more people became fascinated.

"I found Ba Si was a genius and very talented, so I collected all the cigarette packs carrying her pictures," says Lu Weixie, curator of the Fuzhou Panda Art Museum.

Later, as Ba Si got older, Fuzhou Panda World shifted the focus to its aging problems.

"Every morning I would ask her to take a walk with me, and then exercise her arms a little bit by teaching her some waving and ball-holding gestures," Shi Feining says. "But nowadays, she is always too tired to go far and her arms are getting stiff."

In 2001 Ba Si's health really began to deteriorate. She had high blood pressure and cataracts. Her ailments provided first-hand, key information for panda disease prevention and treatment.

Ba Si's blood pressure doubled and she had frequent nose bleeds. She took daily medication to lower and stabilize her blood pressure.

Director Chen Yucun says they shared their diagnosis and treatment with panda raisers in Hong Kong, Ji'nan, Dalian and Shanghai and saved many sick pandas.

Dr Zhao Guangjian from the Fuzhou Southeast Eye Hospital operated on Ba Si to remove her cataracts. He said the surgery was one of the most difficult he had performed.

"Since there were no set medical procedures for panda cataracts, the operation on Ba Si's eyes took almost an hour. A similar operation on a human would only take several minutes," Zhao says. The operations were successful. Panda experts had learned more.

But seven months ago, Ba Si, experienced her most serious ailment in around 30 years of life.

Since pandas eat so much bamboo, their intestines get pricked and injured, but they have a natural mechanism to heal the wound and expel the scab. The process usually takes 15 days to a month and the panda appears to have diarrhea, but this time Ba Si had diarrhea for much longer, Chen explains.

No one had noticed anything wrong with Ba Si, who was just lying around, but suddenly on June 1 last year she was absolutely still, lying on the ground.

Doctors thought it might be enteritis, an inflammation of the intestine.

"If it was enteritis, it could be cured with antibiotics, but in the next four days and nights we tried everything we could think of to cure enteritis, and Ba Si was still in a coma, with no sign of improvement," Chen says.

Chen worried whether a panda around 30 years old could survive this time. But he didn't give up, he kept a close watch over Ba Si and one day he found her moving, with a painful expression. She crawled around and lay in strange positions. Her feces and urine were abnormal. Chen diagnosed her with pancreatitis, inflammation of the pancreas.

Ten days after the treatment, Ba Si's condition improved greatly. She survived again.

Ba Si is really old now. Though she has recovered, she's no longer interested in communicating with her human friends. Nor does she like exercise. Besides eating and sleeping, she's often seen leaning quietly against an eucalyptus tree. But Chen is still quite optimistic about Ba Si's future. He hopes that by adjusting her diet scientifically, keepers will help her live comfortably.