Panda cubs Mei Lun and Mei Huan sleep at their mother's feet at the Atlanta Zoo in Atlanta, Georgia, US November 14, 2013. The cubs will sent back to China on Thursday[Photo/Agencies]

Mei Lun and Mei Huan, born on July 15, 2013 at Zoo Atlanta in Georgia, were the first surviving US-born pair of giant panda twins.

Giant panda Bao Bao celebrates her two-year birthday at the Smithsonian's National Zoo in Washington on Aug 23, 2015 amid a large crowd of fans. Chen Weihua/China Daily

Bao Bao, born on Aug 23, 2013 at the Smithsonian's National Zoo in Washington DC, was the child of the superstar couple Mei Xiang and Tian Tian, who were sent to the US in 2000 under the cooperative breeding agreement. On her 100-day birthday, Bao Bao became the first panda to receive blessing videos from both the first ladies of China and the US, Peng Liyuan and Michelle Obama.