Washington zoo’s panda mom may be pregnant once again

WASHINGTON — Bei Bei, the Smithsonian National Zoo's giant panda cub, is about to turn 2. For his birthday, he will get a special ice cake, but he might also get a surprise — a new sibling.

The zoo's giant panda experts say they think Bei Bei's mom, Mei Xiang, may be pregnant. But panda reproduction is complicated, to say the least.

To start off with, female pandas have only a very short time when their bodies are ready to become pregnant — about two or three days a year.

Giant pandas in zoos often don't mate on their own. So at the end of May, panda experts performed a medical procedure to help Mei Xiang have a cub.

"Right now, we're sort of in the wait-and-see mode," said Michael BrownPalsgrove, the giant panda curator.

Panda experts look for hints of pregnancy. One sign is rising hormone levels, which research veterinarian Pierre Comizzoli said he expects to see in Mei Xiang for the second time soon. Once that happens, it takes about 45 to 55 days for a cub to be born.

Nothing is black and white with pandas, though — except for the panda itself. Hormones also rise during what's called a "pseudopregnancy," when the panda acts pregnant but actually isn't.

In past pregnancies, panda experts have sometimes seen the fetus by taking an ultrasound scan of Mei Xiang's belly, but that's easier said than done.

"She's a pretty large animal, and the fetal development is pretty tiny," Comizzoli said. (At birth, pandas typically weigh about four to six ounces and are about the size of a stick of butter.)

The experts won't be sure Mei Xiang is pregnant until the end of the 45-to-55-day period, at which point, Comizzoli said, "there's either a cub on the ground or there's not."

Giant pandas, found in the wild only in China, are relatively new to U.S. zoos. The first pair arrived at the National Zoo in 1972. LingLing and Hsing-Hsing (sing sing) were a gift from the Chinese government to the United States. The pair produced five cubs between 1983 and 1989, but none survived more than a few days.

Those early losses were learning experiences for the zoo's panda team.

"We've made a lot of progress in terms of monitoring everything we can and this period of time where we don't really know what's going on," Comizzoli said.

The zoo's second pair, Mei Xiang and Tian Tian, who arrived in 2000, are threetime parents. Tai Shan, who is 12, and Bao Bao, who's almost 4, live in China.