CHENGDU, China (Reuter) - Chinese scientists hailed the recent successive births of two baby pandas as a sign of progress toward saving the endangered species, but said the animal could still be extinct within 100 years. "Bringing up pandas in captivity is very difficult," Li Shaochang, director of the Chengdu Research Base of Giant Panda Breeding in southwest Sichuan province, said in an interview. The research base is the heart of China`s campaign to save its national emblem from extinction and has been the pioneer in using artificial insemination to reproduce the notoriously frigid and infertile animal. Giant panda Bing Bing gave birth to a female baby on August 25 at the centre. That success was followed on September 7 by the birth of male twins to Ya Ya. One twin was stillborn. Both pandas gave birth only after being artificially inseminated, Li said. The two fluffy babies, the older about the length of a man`s foot and the second just bigger than a hand, are taken five times a day from their mothers for health checks as part of China`s costly drive to save the panda. Each is weighed, given extra food in the form of a mixture of sheep`s milk and other nutrients and has its faeces tested, said Li Guanghan, deputy director of the research centre. Lying mewling in a temperature-controlled incubator, the male, its skin mottled pink and black and covered with a fine blond hair, weighed in last Thursday at 584 grams. The older, exactly one month old last Thursday, touched the scales at 868 grams and already looked more like a panda with its fur growing in panda trademark black and white. An adult panda on average weighs about 100 kg. The number of China`s pandas has dwindled to about 1,000 and without help the animal could die out in 40 to 50 years. Rearing a cub is a constant battle for their keepers. The tiny animals are vulnerable due to their small size, their weak immune system and their absolute dependence on their mother`s milk that makes hand-rearing impossible. Another danger comes from the mothers themselves. The large, ungainly animals, weighing about 1,000 times more than their babies, often roll over and crush their newborns to death. The reason keepers cannot risk separating cubs from their mothers is because the babies are unable to pass waste without stimulation by the mother, who licks her young.