Zookeepers in Atlanta and San Diego are hopeful their giant pandas are pregnant, which would create a record U.S. baby boomlet of the rare species that began this month with the birth of a cub at the National Zoo.
The possibility of three U.S.-born cubs in the same year reflects the coming of age of the giant pandas on loan from China in the past several years as well as a burst of scientific knowledge on producing and caring for their offspring. Artificial insemination techniques are more precise; pregnancy tests are more accurate; and the odds of a fragile newborn surviving are improving dramatically.
Cub births, and survival, have also risen in China. Advances have been especially notable among twins; whereas one newborn was often doomed in the past, now both routinely make it to adulthood.
At the National Zoo, the 12-day-old cub has developed darkened skin around its eyes and on its ears, back and hind legs, the beginnings of the distinctive giant panda appearance that will be completed when its dark fur grows in.
In Atlanta this week, zookeepers began a round-the-clock birth watch, reporting that the zoo's artificially inseminated female, Lun Lun, is eating less, resting more and showing other signs of pregnancy -- or the false pregnancy for which pandas are notorious. In San Diego, the zoo's top panda expert said yesterday there are "hopeful signs" that two-time mother Bai Yun is pregnant.
"It's fantastic to think we've gone in a decade from having no births to potentially having births in three different institutions," said Lisa M. Stevens, the National Zoo's assistant curator for giant pandas. "It's inspiring in the sense that you can take a critically endangered species and make the kind of progress we have made in a decade."
The National Zoo's cub remains in its mother's arms most of the time, though Mei Xiang left it three times in the last five days to get a drink of water in the next room, Stevens said. The cub has been quiet in those times, and Mei Xiang might be preparing her newborn to spend more time on its own.
"We have food strategically placed so she practically has to walk on [the food] to get to the water," Stevens said, but the mother panda has not eaten since the birth. Keepers hope she will get something to eat and leave her cub long enough to allow veterinarians to examine the cub's vital signs and determine its sex. "We're basically following Mei Xiang's lead," Stevens said.
So far, zoo staffers have seen the cub only through the cameras in the birthing den that are also connected to the Internet -- the same images that people worldwide have been able to view. Stevens said keepers could "see the little claws on its feet" earlier this week. The Panda House is closed to the public for at least three months, but the yard is open, and male Tian Tian can sometimes be seen there.
Panda newborns are tiny and vulnerable, but Stevens said she is encouraged by signs that Mei Xiang is developing into a reliable, tender mother. The cub is fattening up and acquiring antibodies from its mother's milk, she said.
"Every day that passes, I feel more comfortable, but not until it looks like a panda and it's eating bamboo -- then I will really begin to relax," she said.
Don Lindburg, the San Diego Zoo's panda conservation team leader, credits the current breeding success in part to active information trading on insemination techniques, hormone monitoring and other pregnancy-related topics. "Now we are moving into a phase where, hopefully, we can see a lot of collaboration on infant rearing," he said.
