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If you follow pandas, you know that one of the reasons that we have hope for the survival of the species is that scientists have been able to perfect artificial insemination techniques. Most of the pandas born in captivity during the last two decades have artificial insemination to thank. But lately we've had a run on cubs born after their parents did it the natural way: good, old-fashioned panda sex, with no zoo staff involved. Might this be the wave of the future?
This year's mating successes start with Gao Gao – a father of three – who is the studmuffin of the panda world. Gao Gao is a very lucky panda to be alive, much less procreating so much. In March 1993, the young Gao Gao (possibly no more than a year old) was taken to a nature reserve in China when he was found injured. He was dehydrated and the left side of his head was bloody where nearly two-thirds of his ear had been torn away.
He was nursed back to health, and in 2003, was sent to the San Diego Zoo to become the new mate of Bai Yun. Bai Yun's former panda partner, Shi Shi, was exiled to China "after years of showing more interest in bamboo than in mating with Bai Yun." (Panda Passion at San Diego Zoo)
From the beginning, it was clear that Bai Yun was in for more fun that she'd had with Shi Shi. Right after they met, Gao Gao tried unsuccessfully to mate with her, and once she was fertile, they mated three times. Head of the Zoo's panda team Don Lindburg remarked, "We just couldn't believe that this could come off so quickly. I am beyond surprised." (Panda Passion at San Diego Zoo)
It was even more remarkable that later that year, the cub eventually known as Mei Sheng was born – the first cub born in the US as the result of natural mating. (Mei Sheng will be returning to China in October 2007 to become part of the breeding program.) Gao Gao repeated the feat in 2005, when cub Su Lin was born from natural mating with Bai Yun.
Now the San Diego Zoo is celebrating the birth of Gao Gao's third cub with Bai Yun – her fourth. Her cub was born on August 3 and is the only cub born in the U.S. this year. Gao Gao's record as a sire would be perfect – except his virility unfortunately didn't extend to artificial insemination, when an effort this year was made to inseminate Mei Xiang at the National Zoo using his sperm.
Because Gao Gao was born in the wild, his bloodline is far less common than that of Tien Tien, the male panda at the National Zoo in Washington, DC. Tien Tien, who has already fathered the cub Tai Shan, is the son of Wolong's big stud Pang Pang, whose bloodline is very well represented in the captive panda population.
So this year, the National Zoo reached an agreement with the Wolong breeding center to permit Mei Xiang to be inseminated with Gao Gao's sperm – the first time semen was exchanged between zoos in North America. The Zoo's reproductive specialist, Dr. JoGayle Howard, brought the container containing Gao Gao's sperm back from San Diego. She notes, "The sperm went first-class. I did not." (Zoo Playing Matchmaker With a California Boy)
Alas, even with the special care, Gao Gao's sperm didn't do the trick, so to speak. Mei Xiang experienced a pseudopregnancy, and not the real thing this year, so she and Bai Yun can't compare notes on their cubs, who would have been approximately a month apart. Bai Yun and Gao Gao's cub will be the only one born in the U.S. this year, after the Memphis female, Ya Ya, miscarried after an artificial insemination attempt.
But Bai Yun isn't the only panda to conceive naturally this year. Tiergarten Schönbrunn, the zoo in Vienna, is also the proud home of a new cub. Zoo officials there didn't even try to inseminate their female panda, Yang Yang, after spring mating activities with male panda Long Hui. Schoenbrunn Zoo's director, Dagmar Schratter, said that her team had wanted "to let nature run its course." ('Nature runs its course' in Vienna panda birth)
The Vienna Zoo had almost given up, however, when an August 6 ultrasound showed no signs of a cub. To everyone's surprise, on August 23, "squealing sounds coming from a litter box in the panda house…grabbed the Austrian zookeepers' attention." (Zoo's surprise at first natural-born panda) Yang Yang had given birth to twins, although one of the two cubs did not survive. Both the San Diego and Vienna cubs appear to be healthy and thriving.
In 2006, 31 pandas were born in captivity, with 28 surviving. The captive breeding program was touted as a major success, largely due to artificial insemination. (Pandas Finally Breeding in Captivity) Scientists disparaged the pandas' natural breeding abilities, claiming that "pandas just are not very interested in sex," and that "the panda population in the wild had become so fragmented that when two bears of the opposite sex met, they didn't even know what they were supposed to do."
Gao Gao and Long Hui may just be proving them wrong. While it is unlikely that many zoos will take their chances like the Vienna zoo did, and not try to inseminate at all, we could see a resurgence in natural breeding attempts, as zoo scientists try to figure out why so many natural efforts were successful this year, while several closely-watched insemination efforts did not result in panda pregnancies. Long Hui was captive-born at Wolong, so it's probably not just that Gao Gao came from the wild. Maybe more X-rated activity going on at the zoos will help us continue to learn more about the mysteries of panda mating and lead to even more new cubs each year.
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