Giving each other space may not work in every relationship, but it's what keeps the magic alive for the very fertile giant panda pair at the San Diego Zoo.
Since 2003, Bai Yun and her consort, Gao Gao, have produced three cubs, making them one of the most reproductively successful panda couples ever in captivity. Their youngest offspring, a chubby female, will be named Monday when she reaches 100 days old, following Chinese tradition.
For all but two days of the year, Bai Yun (White Cloud) and Gao Gao (Big Big) lead separate lives, gnawing on bamboo and taking long naps in pens far apart, much as wild pandas — naturally solitary creatures — would hide from each other in mountain forests.
But when Bai Yun enters her brief fertile periods, zookeepers make sure Gao Gao is there, sniffing her through a perforated gate zookeepers call the "howdy door" until her chirps and bleats indicate she's ready to get down to business.
"For 363 days a year they don't want to have anything to do with each other," said Ron Swaisgood, co-head of the zoo's panda research unit.
Pandas are notoriously poor breeders — one reason their species is endangered — and females have only three days a year in which they can conceive. Only about 1,600 giant pandas remain in the wild, and fewer than 180 live in captivity.
While pandas have been born at the zoos in Washington, D.C., and Atlanta, Bai Yun and Gao Gao have been the most successful. Bai Yun has had four panda cubs — three with her "super" mate.
Bai Yun gave birth to her first cub in 1999 through artificial insemination from her first arranged suitor, Shi Shi (Stone). It was the first giant panda cub in the U.S. after a decade of failed breeding attempts.
Bai Yun also gave birth to a male panda in 2003 and to a female panda in 2005 before having her latest this year.
Gao Gao arrived in San Diego in 2003 after veterinarians gave up on Shi Shi, who turned out to be older and less virile than originally believed and was returned to China.
Putting the virgin Bai Yun with Gao Gao, who had not mated before, caused some concern. Swaisgood thought it might be like "the blind leading the blind." Instead, Gao Gao surprised everyone by mating with Bai Yun three times in a single day.
Gao Gao is aggressive during the first 24 hours of her cycle and then wanders back to his bamboo pile once he's had his fill — even if Bai Yun beckons him with her customary booty-shake.
"He only has interest in her for one day, but day two or day three, when she's still exhibiting interest, he just has nothing to do with her," said Kathy Hawk, the zoo's senior panda keeper. "He seems to be a one-shot guy, but she's gotten pregnant each time. He knows what he's doing."
The newest cub remains hidden with Bai Yun in a cozy den that can only be seen by the public via Webcam. The zoo will announce the cub's name from among four finalists: Li Hua (Beautiful China), Ming Zhu (Bright Treasure), Xiao Li (Little Beauty) and Zhen Zhen (Precious).