Giant panda cubs play at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)

A giant panda cub plays at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)

Giant panda cubs play at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)

Visitors view giant panda cubs at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)

A giant panda cub eats bark at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)

Giant panda cubs play at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)

A giant panda cub eats a tree branch at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)

A giant panda cub plays at the giant panda base in Chengdu, capital of southwest China's Sichuan Province, Jan. 31, 2014. A panda-themed carnival was held at the base during the Spring Festival holiday. (Xinhua/Huang Xiao)