July 31, 2013 at 9:08 AM ET
One of Washington’s most famous couples may be expecting.
The Smithsonian's National Zoo is hoping Mei Xiang and Tian Tian, their giant pandas, may have a new cub on the way. Mei Xiang began showing hormonal changes and sensitivity to noise that may indicate she is pregnant — or experiencing a false pregnancy, which is common for pandas.
"You can't tell from her behavior,” said Rebecca Snyder, curator of mammals for Zoo Atlanta. “The only sure way to tell is, she either gives birth or if you get lucky, you may get an ultrasound image."
The zoo closed the area around Mei Xiang’s den to the public to help keep that part of the panda house quiet to accommodate her noise sensitivity.
National Zoo vets, who had Mei Xiang artificially inseminated in March, noticed a spike in her hormones last Friday. They will continue to conduct ultrasounds regularly on her but giant panda fetuses do not start developing until the final weeks of gestation, the zoo said in a statement.
Gestation for a giant panda ranges from 90 to 160 days, with an average pregnancy lasting 135 days, according to the zoo. The wide range in gestation occurs because the fertilized panda egg usually floats free before it implants in the mother's uterus and begins to develop.
Mei Xiang has given birth to two cubs, one in 2005 and another one that died last September a week after it was born.
Only four American zoos have endangered giant pandas, all of them on loan from China. The San Diego Zoo's panda Xiao Liwu celebrated his first birthday Monday with a giant cake.
Two weeks ago, Zoo Atlanta celebrated a rarity when they welcomed baby panda twins.
"There haven't been twins born in the US for 25 years,” Snyder said.