The Chinese call their giant pandas a national treasure. But pandas are more than that. They are one of the planet's treasures.

Sichuan Province in southwestern China is home to 80 percent of China's wild giant pandas. Its giant panda reserves are not only science research centers, but also tourist attractions that receive hundreds of thousands of visitors from around the world each year. Today we'll go to one of the nature reserves in Sichuan and learn about what their daily life is like.

Despite the early morning chill, tourists are standing in a long queue outside the Giant Panda Breeding and Research Center in Chengdu, capital city of Sichuan Province, waiting to enter when it opens. Among them is a group of college students who are excited about their trip.

"I heard that giant pandas go outdoors only when they are in a good mood. I hope they feel happy today and can come out for us to see. I wish I could touch them."

Latest research shows that despite bamboo being their main food, pandas in the wild sometimes catch their prey, perhaps to spice up their menu a little. So scientists have warned people not to pat a panda.

This panda reserve is actually a big park composed of a few hills and mountains. Inside the park there are several panda habitats.

Huang Jie , a guide at the center, says that like many other creatures in the wild, pandas in captivity still keep the habit of constantly changing the place they live.

"Psychological problems and behavioral disorders are likely to come into play if pandas are kept in the same place for long. So we keep changing homes for them. And their outdoor activities are very colourful, with swings, bars and other toys."

The giant panda lives in the most biologically rich forests on earth. Their favorite homes are mountain bamboo forests with altitudes of 1,500 to 3,400 meters above sea level, where temperatures remain below 20 degrees Celsius all year round.

Huang Jie explains.

"Winter is their favorite season. Their thick fur protects them from the cold outside. So they do not hibernate, and come out searching for food even in chilly winter."

Pandas spend most of their day -- more than 16 hours -- eating and chewing bamboo leaves so as to obtain enough protein from this not-so-nutritious plant. They spend the remaining eight hours sleeping.

Scientists found that giant pandas were meat-eating animals and caught their prey some eight million years ago. They gradually turned to rely on bamboo because the plant is more widespread and a lot easier to find. However, the digestive system of the panda remains unchanged. Unlike cows, sheep and other grazing animals which are endowed with the ability to convert grass into food they can digest, the pandas have to eat a lot in order to get the energy they need.

"A panda needs 20 to 30 kilograms of bamboo each day. However, only 17 percent of the bamboo they eat is digested. Because of bamboo's relatively low nutritional value, pandas have to eat a large amount in order to survive. "

Since pandas are very wasteful and somewhat picky about what they eat, each panda in the reserve is provided with 50 kilograms of bamboo every day.

A vital part of the research center is breeding baby pandas.

Part of the process can be viewed by tourists through a glass window. Baby pandas are more active than their parents and move a lot in their cribs.

Huang Jie says new born pandas have a weak digestion system, so they have to be fed very carefully.

"Babysitters have to pat the newborns softly on the stomach to help them defecate. In the wild, the process is done by the mother panda massaging the cubs with her tongue."

Zhang Man, a tourist from Hubei Province in central China, is impressed with the panda cub.

"I have seen pandas in different zoos. But the ones here are more active, especially those cubs which are so cute!"

Jordan Mariuma comes from the United States. He has spent a whole morning in the reserve to see more than 20 pandas.

"Pandas are beautiful. I'm happy to see them well attended. It's my first time to see pandas and I've seen about 20. They're so cute that it's impossible not to fall in love with them."

It's interesting that the best panda food in the world, which is widely used in panda reserves in China, was developed by an American.

Chinese researchers are breeding captive pandas to increase the population. When a captive panda gives birth to twins and abandons one of the cubs, scientists try to raise the abandoned baby. But it is difficult for humans to raise baby pandas. The cubs have trouble digesting food other than panda milk.

In 1999, Mark Edwards, chief nutritionist at the San Diego Zoo in the US, developed a baby panda food. It is a mixture of human baby formula and a milk substitute used for feeding puppies. The mixture is enough like panda milk that it is easy for a baby panda to digest. This promising new food has raised hopes that more baby pandas can be reared successfully.