Bai Yun, a giant panda at the San Diego Zoo in Southern California.Aug.6 - Bai Yun, a giant panda at the San Diego Zoo in Southern California, has given birth to a healthy cub, her fourth offspring, zoo officials said on Saturday.The father is Gao Gao, also at the zoo, said the officials, adding that the cub's gender will not be determined for months.Bai Yun gave the birth on Friday, said the officials who refused to be named.The cub will stay off exhibit for several months, according to the officials, who refused to be named.Bai Yun, 16, had given births to three cubs at the zoo before. They were Hua Mei in 1999, Mei Sheng in 2003 and Su Lin in 2005.Including the cub, the San Diego Zoo has five pandas, more than any other U.S. zoo.In an effort to impact the decline of wild populations, the Zoo, working with the World Wildlife Fund, U.S. Fish and Wildlife Service, the China Wildlife Conservation Association, and the Chinese Association of Zoological Gardens, has committed significant resources to the long-term study of giant pandas in captivity and in situ conservation efforts to reverse the situation.It is estimated that there are approximately 1,600 giant pandas left in the world due to habitat destruction and fragmentation, bamboo depletion, and poaching. The San Diego Zoo contributes more than 1 million dollars each year to China, part of which is designated for wild habitat protection projects.