SAN DIEGO -- For hundreds of thousands of passionate panda watchers, the birth at the San Diego Zoo today of a new panda cub is an event well worth celebrating, especially given that the mother is probably the second-oldest known panda ever to successfully deliver. And thanks to some high-tech imaging, the zoo was able to monitor the pregnancy every step of the way.
For weeks, the panda team at the zoo here has been on tenterhooks, hoping against hope that the 20-year-old mother, Bai Yun, would carry to term what they were nearly certain was a healthy cub. But since Bai Yun had had an unsuccessful pregnancy last year, and because of her age, the team was unwilling and unable to say with certainty that they would soon be meeting a brand-new panda.
Now, though, champagne corks are surely popping in San Diego as the approximately 4-ounce pink and gray newcomer, still without sight, joins one of the most beloved species on Earth. Unfortunately, the public will have to wait for an unknown amount of time to meet the new panda, as Bai Yun and her new cub will spend weeks hidden away in the mother's den, and the only chance the world will have to see the new offspring will be if Bai Yun happens to move with it in front of what is known as the "Panda Cam."
As part of Road Trip 2012, I got a chance to visit with Bai Yun's medical team as the members conducted a very early morning ultrasound earlier this month. And though I wasn't allowed to see the pregnant panda, for fear of upsetting her -- no unfamiliar people were being allowed immediately near Bai Yun -- I was just a few feet away as they conducted the procedure (see videos below).
Until Friday, zoo officials were keeping mum about Bai Yun's progress, and in fact had become pessimistic about the outcome after an ultrasound on July 24. But a new ultrasound seemed to have turned everything around. "Based on hormone testing, behavioral observations, and ultrasounds, the staff (began) their birth watch for a cub," the zoo said in a release Friday. "Ultrasound video taken (July 26) clearly showed a panda fetus. The spine and a leg are visible and veterinarians were also able to detect the heartbeat."
Though Bai Yun has had five previous cubs, the zoo staff was not certain she would be able to carry another pregnancy to term. In large part, that's because of the panda's age, and because of last year's disappointment. And while during my visit to the zoo the team attending to Bai Yun was upbeat and very hopeful that she would be able to beat the odds and give birth to a new cub, they weren't getting attached to the idea.
The team was leaning on ultrasound to help them determine the state of things, but they had other technology at their fingertips as well, specifically a device originally developed for the military known as a forward-looking infrared camera (FLIR). According to the zoo's director of reproductive physiology, Barbara Durrant, FLIR was used to give the panda staff a look at the heat signature inside Bai Yun's belly, allowing them to examine a heat spectrum that generates the full range of colors between black and white. (Durrant said an in utero cub would put out a red heat signature.)
Durrant began using FLIR about a third to halfway through Bai Yun's gestation period -- which has ranged from between 101 and 134 days during her previous pregnancies. On about day 60 after Bai Yun's breeding with a 20-year old male named Gao Gao -- with whom she's had four previous cubs -- the team began to see promising signs with the tool. That's a much earlier warning that there might be a new cub in Bai Yun's future than what ultrasound is capable of.
But while that was a signal that something was happening, the embryo had yet to implant in the mother's uterus, Durrant said. That's not unusual, though: Pandas and Sun Bears are known to have their placentas start to grow prior to implantation. "A panda's fertilized egg remains suspended until a trigger in the environment indicates it is time to implant," the zoo release explained. "The trigger is still unknown to scientists. Giant pandas routinely delay the implantation of the fetus as long as four months."
As I watched from off to the side, a clicking sound -- which Bai Yun associates with reward -- indicated that the medical staff was trying to convince her to change positions so that her feet would be resting on something.
Ultimately, while the ultrasound didn't tell the staff anything about whether Bai Yun would be able to deliver her new cub, the team insisted on doing the procedure about once a week -- and more in the final weeks -- because, said zoo veterinarian Meg Sutherland-Smith, "it's an opportunity to gather data to learn about fetal growth rates. The more data we collect, it helps us and other institutions with knowing" more about panda pregnancies.
Twins and triplets
Over the years, though Bai Yun has never given birth to more than a single cub at a time, she's historically shown early signs of being pregnant with two or even three. This year, however, there were never signs of more than a single cub, and that was something that worried the staff.
Last week, though the ultrasound showed the sign of a heartbeat, it didn't "look great," Durrant said, meaning she wasn't altogether optimistic about the outcome of Bai Yun's pregnancy.
But now, Bai Yun and her tiny offspring will remain in her den for as long as five months before moving back into the public panda exhibit. Indeed, the zoo staff won't even know the sex of the youngster until they are able to examine it, which could be as long as two months from now. That should be about the same time its characteristic black and white markings begin to show up.
For now, then, the countless panda fans -- the "pandamaniacs," as they're called -- will have to make do with obsessively watching the Pandacam for their own glimpse of the new cub. But before too long, if all goes well, the cub will be brought out into the panda exhibit for all to see.
Then, it will have about three years at the zoo. After that, it's unclear. With the exception of a few pandas in a Mexican zoo, the entire species belongs to China, and that country determines what happens to each once they turn three.
In the meantime, the San Diego Zoo staff must be feeling nostalgic about their pandas. After all, given that the zoo has just one adult female, and she may be at the end of her cub-bearing years, it's very possible that the zoo has seen its last panda cub for a long time. But for now, the sound of corks popping coming from San Diego indicates some very happy panda staffers.