Giant panda cub Xiao Liwu (right) and its mother Bai Yun stay together during his first birthday celebration at the San Diego Zoo, California, the United States, July 29, 2013. Zoo staff made a cake with ice, bamboo and some of the cub's favorite fruits and also boxes wrapped as gifts. The cub Xiao Liwu was born on July 29, 2012, as the sixth baby of its mother Bai Yun. Photo: Xinhua
 

Giant panda cub Xiao Liwu tries to reach a gift box on the tree during his first birthday celebration at the San Diego Zoo, California, the United States, on July 29, 2013. Zoo staff made a cake with ice, bamboo and some of the cub's favorite fruits and also boxes wrapped as gifts. The cub Xiao Liwu was born on July 29, 2012, as the sixth baby of its mother Bai Yun. Photo: Xinhua
 

Giant panda cub Xiao Liwu (right) and its mother Bai Yun enjoy the birthday cake during his first birthday celebration at the San Diego Zoo, California, the United States, on July 29, 2013. Zoo staff made a cake with ice, bamboo and some of the cub's favorite fruits and also boxes wrapped as gifts. The cub Xiao Liwu was born on July 29, 2012, as the sixth baby of its mother Bai Yun. Photo: Xinhua

Giant panda cub Xiao Liwu plays with gifts during his first birthday celebration at the San Diego Zoo, California, the United States, July 29, 2013. Zoo staff made a cake with ice, bamboo and some of the cub's favorite fruits and also boxes wrapped as gifts. The cub Xiao Liwu was born on July 29, 2012, as the sixth baby of its mother Bai Yun. Photo: Xinhua 

Giant panda cub Xiao Liwu plays with gift boxs during his first birthday celebration at the San Diego Zoo, California, the United States, July 29, 2013. Zoo staff made a cake with ice, bamboo and some of the cub's favorite fruits and also boxes wrapped as gifts. The cub Xiao Liwu was born on July 29, 2012, as the sixth baby of its mother Bai Yun. Photo: Xinhua 

Tourists watch giant panda cub Xiao Liwu during his first birthday celebration at the San Diego Zoo, California, the United States, on July 29, 2013. Zoo staff made a cake with ice, bamboo and some of the cub's favorite fruits and also boxes wrapped as gifts. The cub Xiao Liwu was born on July 29, 2012, as the sixth baby of its mother Bai Yun. Photo: Xinhua