A staff member takes care of a giant panda cub at the Qinling Giant Panda Research Center in northwest China's Shaanxi province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

Giant panda Ya Ya takes care of her baby at the Qinling Giant Panda Research Center in northwest China's Shaanxi Province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

A staff member helps giant panda Ya Ya to breastfeed her baby at the Qinling Giant Panda Research Center in northwest China's Shaanxi province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

A staff member takes care of a giant panda cub at the Qinling Giant Panda Research Center in northwest China's Shaanxi province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

Photo taken on Aug. 20, 2021 shows a giant panda cub at the Qinling Giant Panda Research Center in northwest China's Shaanxi province. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

A staff member helps giant panda Ya Ya to breastfeed her baby at the Qinling Giant Panda Research Center in northwest China's Shaanxi province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

Photo taken on Aug. 20, 2021 shows a giant panda cub at the Qinling Giant Panda Research Center in northwest China's Shaanxi province. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

A staff member helps giant panda Ya Ya to breastfeed her baby at the Qinling Giant Panda Research Center in northwest China's Shaanxi province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

Giant panda Ya Ya takes care of her baby at the Qinling Giant Panda Research Center in northwest China's Shaanxi province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

Giant panda Ya Ya takes care of her baby at the Qinling Giant Panda Research Center in northwest China's Shaanxi province, Aug. 20, 2021. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

Photo taken on Aug. 20, 2021 shows a giant panda cub at the Qinling Giant Panda Research Center in northwest China's Shaanxi province. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)

Photo taken on Aug. 20, 2021 shows a giant panda cub at the Qinling Giant Panda Research Center in northwest China's Shaanxi province. In 2021, the research center has witnessed the birth of four cubs, which raised the number of captive Qinling giant pandas to 36. (Photo: Xinhua)