Panda Passion At San Diego Zoo

Love was in the air at the San Diego Zoo this weekend.

Gao Gao, an 11-year-old male giant panda who recently arrived from China, mated three times with Bai Yun, the San Diego Zoo's resident female panda.

"We just couldn't believe that this could come off so quickly," said Don Lindburg, head of the zoo's panda team. "I am beyond surprised."

Researchers are optimistic that the panda mating — a first in San Diego Zoo history — may yield another cub.

Bai Yun gave birth to a cub in 1999 after she was artificially inseminated.

Gao Gao arrived from China in mid-January, replacing Shi Shi, a 26-year-old male, who returned to China earlier this year after years of showing more interest in bamboo than in mating with Bai Yun.

"We had year after year of frustration," Lindburg said. "To have this naive individual at his first opportunity perform in this way was pretty special."

Gao Gao showed intense interest in 12-year-old Bai Yun from the get-go. When the two met for the first time Thursday, Gao Gao tried unsuccessfully to mount her. The pandas were taken off public display and given privacy after biologists determined Bai Yun had entered a rare period of fertility.

On Saturday, the two pandas were far more interested in each other than in the researchers who kept watch and recorded every chirp and bleat the bears made during mating.

But Gao Gao lost interest on Sunday and spurned Bai Yun's advances. Since pandas are only fertile for two or three days a year, researchers decided to artificially inseminate her Sunday and Monday with frozen sperm from Shi Shi.

"This is just hedging our bets," Lindburg said.

In another first, zoo medical staff did not use anesthesia during the artificial insemination out of concern that they might jeopardize a possible pregnancy from the mating with Gao Gao. A DNA test will be able to tell which panda is the father.

Shi Shi fathered the cub born in 1999, 3½-year-old Hua Mei, who is the first U.S.-born panda cub to survive into adolescence. Under San Diego's panda-loan agreement with China, Hua Mei is to be returned to China this year.

Researchers probably won't know whether Bai Yun is pregnant again until early August, when she would approach the end of a 4½-month pregnancy. There's no way to detect a pregnancy in pandas and females routinely show false pregnancies, Lindburg said.

Panda cubs are about the size of a stick of butter when born, and are hairless and blind. The mother uses her mouth to carry the cub and cradles it on her chest — similar to an ape — for feeding.

Fewer than 1,000 giant pandas exist in the wild, all in China. In the United States, there are panda pairs at zoos in Washington and Atlanta.