With the departure of the panda cub Tai Shan imminent, Zoo officials couldn't have asked for better news this weekend when the female panda Mei Xiang went into early estrus and was artificially inseminated.
Mei Xiang typically ovulates in the spring, so why January? Perhaps she was hoping to snuggle up to her mate Tian Tian for a little warmth; Washington, D.C. is enduring a very frigid cold snap. (Scientists actually don't know what triggers ovulation in the giant panda, whether it's temperature change or the length of daylight or any other environmental factor.)
So on Saturday morning, the pair were permitted a brief opportunity to "snuggle." But giant panda sex is a very tricky thing, and for it to work, it takes more than two to tango.
Rather, it takes a whole cadre of scientific researchers who, working in collaboration with scientists in China for more than a decade, have created a procedure that allows the pandas a chance to naturally conceive before intervening with artificial insemination. The last time, however, that the planets aligned and a baby panda was born at the Zoo was five years ago when Tai Shan made his dramatic appearance.
Giant pandas ovulate just once a year and mating must occur during the brief two-day period when the female is fertile. The problem is that the male is not always ready and willing. "They were very playful," explained research veterinarian Pierre Comizzoli, "but nothing was really happening naturally."
After a few hours, the staff had to intervene. The pair were separated. Both animals were anesthetized and scientists used an exacting procedure, similar to the successful insemination in 2005 that delivered Tai Shan.
But this time, Comizzoli reports a few lucky circumstances might better the chances of a new panda offspring. The first is better hormone information. A large number of volunteers were watching over the female panda for early signs of estrus. They were on hand to observe when the creature urinated. And then the animal keepers rushed into the enclosure to collect it, and then rushed it to the lab for analysis, allowing the researchers to peg a much narrower time frame for ovulation. "We knew almost exactly when ovulation occurred," said Comizzoli.
The second is more (how to put this delicately?) sperm. By comparison with 2005, Comizzoli says, there was enough sperm available from Tian Tian that the researchers were able to artificially inseminate Mei Xiang, once on Saturday evening, and then again, early on Sunday morning.
So now, just as Tai Shan's days at the Zoo are drawing to an end, officials are allowing themselves just a glimmer of hope, that maybe, just maybe, a new little cub will replace him. "Every year," says Comizzoli, "we perform the same procedure, but this time we were able to do two."
Both pandas are recovered now from the anesthesia and they're both out moving around their yards. Animals blissfully filling themselves on bamboo. It's but for us anxious humans to wait and see.
Update: This post has been updated. A correction was made to indicate that it was the animal keepers who collected the urine from the panda animal enclosures and not the volunteers.