Will the National Zoo's Giant Panda Cub Die?

A panda cub's first days are filled with potentially perilous obstacles.

Mei Xiang, the female giant panda at the Smithsonian's National Zoo in Washington, eats breakfast. Mei Xiang gave birth to a cub, which has since passed away.

Mei Xiang, the female giant panda at the Smithsonian's National Zoo in Washington, eats breakfast. Mei Xiang gave birth to a cub, which has since passed away.

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Animal keepers at the National Zoo got a pleasant surprise Sunday night: Mei Xiang, one of the zoo's two giant pandas and its star attraction, gave birth to her second cub in seven years. Now, its handlers have to make sure the cub lives to adulthood.

[Photos: Mei Xiang Gives Birth.]

Pandas are notoriously bad breeders—Mei Xiang was artificially inseminated and has had five false pregnancies over the past several years—but they may be even worse at keeping their young alive. Many giant pandas born in captivity die before reaching adulthood. Just a handful of pandas born in the United States have survived, and of the six (now seven) pandas born at the National Zoo, just one, Tai Shan, has survived. Earlier this year, the first giant panda born in captivity in Japan in more than 24 years died of pneumonia just a week after it was born.

But the Washington, D.C.-based zoo's newest cub (keepers still don't know if it's a male or female) has some key things going for it. According to Nicole MacCorkle, one of the panda's keepers, Mei Xiang has been a successful mother before (to Tai Shan), and has been generally healthier than Ling Ling, the panda whose five cubs all died shortly after their birth during her more than 20 years at the zoo.

"She did a phenomenal job the first time around," MacCorkle says of Mei Xiang. "It's very different than with Ling-Ling. She had chronic uterine infections, so her cubs were born with a compromised immune system. It's comparing apples and oranges."

[Photos: Rabbits Hop to Victory in Jumping Contest]

The key to rearing a successful panda cub is still something of a mystery. When they're born, pandas are about the size of a stick of butter, which makes them easily harmed.

"There's nothing we can pinpoint" in infant panda mortality, she says. "But a lot of it has to do with the fact that they're very small and vulnerable."

According to MacCorkle, the new cub has been vocal and active, which is a good sign, and Mei Xiang has been an attentive mother so far. "We have no reason not to be hopeful with this one," she says.

There's also an off chance Mei Xiang could give birth to another cub by the end of the day, but MacCorkle says that possibility is "becoming more and more unlikely" by the hour.

The zoo's panda keepers likely won't be able to handle the cub for about three weeks, when Mei Xiang is comfortable leaving the panda alone for 20 minutes at a time. During that time, they'll be able to do an initial checkup to determine the cub's health. After about 100 days, zookeepers can be reasonably sure the panda will survive into adulthood, and the public will finally be able to see it. During that 100-day ceremony, the panda will be named.

[Photos: The Annual Weighing of the Animals]

The National Zoo has successfully raised a slew of baby animals in the past several years, including cheetahs, gazelles, and fishing cats—but in 2010, a three-week old red panda cub was found dead in its exhibit.

Like the cub's older brother Tai Shan, if the giant panda baby survives, it'll live in the zoo for four years before heading to China, where it will likely live with its sibling.

Until then, the panda's keepers will have their fingers crossed hoping Mei Xiang is still a good mother all these years later.

"Mei Xiang is an experienced mother," she says. "We're going to let her call the shots on this."

Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at jkoebler@usnews.com

Corrected 9/18/12 10 a.m.: An earlier version of this article misstated the number of giant pandas born in the United States.