Giant panda twins "Ping Ping" (L) and "An An" eat a cake to celebrate their birthday at the Bifengxia breeding base in Ya'an City of southwest China's Sichuan Province, July 6, 2009. Giant panda "Guo Guo", an evacuee from the southwest China earthquake, gave birth to the twins "Ping Ping" and "An An" on July 6, 2008, becoming the first panda to bear cubs since the disaster in Sichuan Province on May 12, 2008. (Xinhua)