Gestation in giant pandas has been estimated to be between 97 and 163 days. Researchers and keepers at the station began 24 hour observations of Bai Yun on July 24, 1999. Researchers will be monitoring Bai Yun and her baby very closely, as the first 24 hours are critical for giant panda cub and mother bonding. They will be observing for signs of weakness or ill-health, adding to the world's store of knowledge about giant panda behavior and reproduction. Although prepared for all contingencies, animal care staff will only intervene if a health risk to one of the pandas develops.
Giant pandas are critically endangered in the wild.
It is estimated that fewer than 1,000 exist today. Bai Yun and Shi Shi arrived at the San Diego Zoo in September 1996 on a 12-year reproductive research loan from China.