Giant panda Chu Xin enjoys the birthday meal at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday. (Photos: Xinhua/Lin Hong)

Giant panda Chu Xin enjoys the birthday meal at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Chu Xin prepares to enjoy the birthday present at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Chu Xin enjoys the birthday meal at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Mu Yun opens the birthday present at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Chu Xin has fun during the birthday party at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Mu Yun has fun during the birthday party at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Chu Xin is seen during the birthday party at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Mu Yun opens the birthday present at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday.

Giant panda Chu Xin prepares to eat bamboo at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday. (Xinhua/Lin Hong)

Giant panda Mu Yun prepares to enjoy the birthday present at the panda hall of Siberian Tiger Park in Changchun, northeast China's Jilin Province, July 30, 2020. A birthday party was held to celebrate the fourth birthday of giant pandas Chu Xin and Mu Yun on Thursday. (Xinhua/Lin Hong)