More than 10 percent of all giant pandas have been killed by starvation or earthquake since 1975, prompting an international rescue mission to save one of the world's most beloved -- and most endangered -- animals.

A team led by Chinese scientists and experts from the World Wildlife Fund, which uses the panda as its symbol, left Peking Monday for an unprecedented trip into the mountain habitats of the world's 1,000 remaining bearlike, white-and-black spotted creatures.

The official New China News Agency said on the eve of the trip that a survey of panda reserves in southwest China concluded that 138 of the animals died in 1975 and 1976 from an earthquake and the sudden dying out of arrow bamboo, the panda's main food. The bamboo died naturally after a once-a-century blooming and naturalists here fear that other bamboo species in the area might follow suit.

The news agency, describing the effects of the disappearing food supply, said, "When a panda is terribly hungry, it will sit quietly waiting for death with both front paws round its head."

"The panda is the World Wildlife Fund symbol and the national treasure of China, so if the panda disappears, the moral blow to the environmental movement would be devastating," said George B. Schaller, conservation director of the New York Zoological Society and one of the expedition leaders. "If we can't save a spectacular animal like the panda, what the hell are we doing?

The World Wildlife Fund officials said the 138 deaths appear to represent a serious decline in the world panda population, which will take considerable time and good fortune to recover. Pandas mate infrequently and usually live by themselves except when a mother is raising a baby. So far, efforts to breed pandas in captivity outside China have failed, forcing zoos to consider experiments in artificial insemination. The Wildlife Fund group says that it hopes a careful survey of the Chinese panda reserves will determine just how much of a setback the animals have suffered, and what if anything can be done to help produce more young and avoid future natural calamities.

Although the arrow bamboo blossoms put out seeds which sprout new bamboo, "it will take several years for the bamboo to grow big enough for the pandas to eat," said Schaller, who is a zoologist specializing in endangered species. Pandas do not hibernate and "in winter, they only have bamboo to eat," he said. "The snow is on the ground and all the other plants are dead."

The Chinese news agency reported recently that villagers in the mountainous area of Sichuan and Gansu provinces tried in 1977 to save some pandas by capturing them and feeding them rice, corn, potatoes and some bamboo shoots.

The news agency reported: "This often presented difficulties, since pandas are particularly strong and while their temperament is generally mild, a panda that senses it is under attack will strike back. The animals were caught by one man dashing toward a panda and covering its head with a blanket, while another tied it up."

Pandas live in 10 special protection zones, eight of them in Sichuan, including the Wolong reserve where the World Wildlife Fund group is going. The other two reserves are in Gansu and Shaanxi provinces.

Pandas have attracted world attention for centuries and were regularly plundered by foreign hunters and zookeepers in the early 1900s. A movie scheduled for production this year, "The Lady and the Panda," is the first U.S.-Chinese coproduction and will tell the story of one of those earlier panda hunts.

Since the communists reunited China in 1949, access to the pandas has been severely restricted. Peking has occasionally made gifts of pandas, such as the two now at the National Zoo in Washington, to enhance China's image abroad. There are now 35 pandas in captivity worldwide.

Besides Schaller, the World Wildlife Fund party includes the British conservationist and wildlife painter, Sir Peter Scott, and Nancy Nash, the fund's liaison officer who made most of the initial contacts with the Chinese. They will apparently be the first foreigners to visit the pandas in their natural habitat since 1949, although dozens of researchers and film-makers have been seeking permission to visit the reserves.

Schaller said they plan to spend at least a week camping in the Wolong reserve, about 150 miles west of the provincial capital of Chengdu.

"One reason the Chinese want to collaborate on this proejct is that they're really worried about the future of the panda," Schaller said.

Schaller said the trip would allow his group to collect as much information as possible from local Chinese naturalists "so we can set up an action plan" to curtail further starvation. He said it might be possible to organize a system of bringing food to the solitary creatures or follow the strategy of capturing and feeding them during the winter. But Schaller said, "I don't relish the idea of wrestling with a full-grown Panda."

Schaller said the bamboo usually propagates in shoots, but only once in every 60 to 100 years puts forth flowers and seeds and then dies away.There are records of these plants going to seed in the 1870s and 1880s. In the past, before China's latest population boom, pandas could range somewhat farther to find food. In the Pleistocene era, about 10,000 years ago, pandas were found all over eastern China, as far north as Peking.