Giant panda females only ovulate once per year, making the birth of these twins even more special. The cubs were born Aug. 15 at Ocean Park, just one day before Ying Ying's 19th birthday.

19-year-old giant panda Ying Ying gave birth to twins at Ocean Park Hong Kong. Ocean Park Hong Kong "As a first-time mother, Ying Ying was understandably nervous throughout the process.

The Giant Panda Cam is composed of 40 cameras operated from a central system by a corps of specially trained volunteers. The webcams broadcast from 7 a.m. to 7 p.m. ET.

Zoo workers are almost finished with the Giant Panda exhibit and the bears are out of quarantine. To stream WUSA9 on your phone, you need the WUSA9 app. Download the WUSA9 app. More Videos.

The next time you visit the pandas at the Zoo or watch the Giant Panda Cam, use these tips and see if you can spot the differences yourself—and tell us if you noticed anything we missed!

Conservations consider giant pandas to be a "vulnerable" species. "The National Zoo’s panda program brings joy to millions of people today as it does the important work of understanding and ...