Giant panda Bao Di has birthday meal at the Pairi Daiza zoo in Brugelette, Belgium, on Aug. 16, 2023. The celebration of the fourth birthday of the panda twins Bao Di and Bao Mei, born on Aug. 8, 2019, was held at the Pairi Daiza zoo on Wednesday. (Xinhua/Zhao Dingzhe)

Giant panda twins Bao Di (L) and Bao Mei have birthday meal at the Pairi Daiza zoo in Brugelette, Belgium, on Aug. 16, 2023. The celebration of the fourth birthday of the panda twins Bao Di and Bao Mei, born on Aug. 8, 2019, was held at the Pairi Daiza zoo on Wednesday. (Xinhua/Zhao Dingzhe)

Giant panda Bao Mei has birthday meal at the Pairi Daiza zoo in Brugelette, Belgium, on Aug. 16, 2023. The celebration of the fourth birthday of the panda twins Bao Di and Bao Mei, born on Aug. 8, 2019, was held at the Pairi Daiza zoo on Wednesday. (Xinhua/Zhao Dingzhe)

Giant panda twins Bao Di (rear) and Bao Mei have birthday meal at the Pairi Daiza zoo in Brugelette, Belgium, on Aug. 16, 2023. The celebration of the fourth birthday of the panda twins Bao Di and Bao Mei, born on Aug. 8, 2019, was held at the Pairi Daiza zoo on Wednesday. (Xinhua/Zhao Dingzhe)

Giant panda Bao Mei has birthday meal at the Pairi Daiza zoo in Brugelette, Belgium, on Aug. 16, 2023. The celebration of the fourth birthday of the panda twins Bao Di and Bao Mei, born on Aug. 8, 2019, was held at the Pairi Daiza zoo on Wednesday. (Xinhua/Zhao Dingzhe)