Subscribe | UPI Odd Newsletter Subscribe SAN DIEGO, July 29 (UPI) -- The San Diego Zoo is in readiness for the birth of twins to pregnant panda Bai Yun, the second litter for the giant panda. All successful panda births are a celebration for the endangered species, but zoo officials have warned that often one of the panda twins do not survive, the San Diego Union-Tribune reported Friday. Advertisement The birth is expected to occur next week. The father, Gao Gao, a 13-year-old panda on loan from China, who arrived in San Diego in early 2003, had mated with Bai Yun and they produced Mei, born two summers ago. "Given that we now have a pair with proven fertility and know-how, we might anticipate a birth every two years for the remainder of their time with us," said panda team leader Don Lindburg.
