Bao Bao returned from the United States in February and celebrated her 4th birthday in her new home at the Dujiangyan base of China Conservation and Research Center for the Giant Panda in Southwest China's Sichuan province on Wednesday. Photo provided to China Daily

Bao Bao celebrated her fourth birthday on Wednesday in her new home at the Dujiangyan base of China Conservation and Research Center for the Giant Panda in Southwest China's Sichuan province.

Base staff members prepared a 50-kilogram cake made of apples, carrot, buns and bamboo as a special treat.

Bao Bao was born in the Smithsonian's National Zoo in Washington in the United States. In February, she arrived in China, via the FedEx Panda Express 777F airplane.

Soon after her arrival in Chengdu, Sichuan province, the 90-kilogram Bao Bao arrived at the Dujiangyan base of the China Conservation and Research Center for the Giant Panda.

Under a bilateral agreement between the National Zoo and China, panda cubs born at the zoo to pandas on loan from China belong to China and have to be moved to China before they reach the age of four to join the breeding program.