More DC Panda-monium Possible This Summer

Could there be more pitter-patter of tiny panda feet at the National Zoo?

Zoo president John Berry told a group of Smithsonian supporters that the latest effort to impregnate female panda Mei Xiang might have paid off. He says tests are now showing a spike in her hormone levels, reports CBS Radio affiliate WTOP. That could mean the birth of a cub in mid-July.

Mei was impregnated with the sperm of a male panda from the San Diego Zoo two months ago when she went into heat.

Panda pregnancies can be tricky, though. Berry says it's still possible she could be having a false pregnancy. If there is another panda cub on the way, a fetus should become visible on ultrasound in the next two or three weeks.

"The one tool that we have in our toolbox to really figure this out, is that Mei is one of only two pandas trained to undergo ultrasound while awake," zoo spokesman John Gibbons told CBSNews.com, which is important for the safety of the fetus. However, the test is less precise than for a human, since it is conducted through a thick layer of fur and the fetus is only a quarter the size of a human fetus.

And last time, Mei refused to enter the ultrasound enclosure four weeks before her cub was born, leaving zookeepers to watch and wait.

The last panda birth at the zoo in 2005 was a huge event. Tai Shan was the zoo's first panda cub to survive more than a few days. He's almost two years old now and remains the zoo's top attraction, drawing more than 2.25 million visitors since his birth.

As of mid-May, he weighed 137 pounds, and still gets thousands of visitors per week.

Tai Shan, his mother Mei Xiang and father Tian Tian are on loan to the National Zoo from China. Under the agreement, any offspring of Mei Xiang must be returned to China after its second birthday, but in April, China extended Tai Shan's stay another two years, reports the Washington Post.