A zookeeper provides fresh bamboo to panda stall in the Calgary Zoo, Canada, Oct. 30, 2019. Panda cubs Jia Panpan and Jia Yueyue in Canada's Calgary Zoo will be moving to the Giant Panda Research Base in Chengdu, capital of China's southwestern Sichuan Province, in early 2020, according to the Calgary Zoo. Jia Panpan, a male, and Jia Yueyue, a female, came to Calgary city in March 2018, and they are now almost 4 years old. The panda twins are leaving Calgary as the term of their loan agreement between Canada and China has come to an end. (Photo by Andrew Soong/Xinhua)

A zookeeper cleans panda stall in the Calgary Zoo, Canada, Oct. 30, 2019. Panda cubs Jia Panpan and Jia Yueyue in Canada's Calgary Zoo will be moving to the Giant Panda Research Base in Chengdu, capital of China's southwestern Sichuan Province, in early 2020, according to the Calgary Zoo. Jia Panpan, a male, and Jia Yueyue, a female, came to Calgary city in March 2018, and they are now almost 4 years old. The panda twins are leaving Calgary as the term of their loan agreement between Canada and China has come to an end. (Photo by Andrew Soong/Xinhua)

Visitors view a panda at the Calgary Zoo, Canada, Oct. 30, 2019. Panda cubs Jia Panpan and Jia Yueyue in Canada's Calgary Zoo will be moving to the Giant Panda Research Base in Chengdu, capital of China's southwestern Sichuan Province, in early 2020, according to the Calgary Zoo. Jia Panpan, a male, and Jia Yueyue, a female, came to Calgary city in March 2018, and they are now almost 4 years old. The panda twins are leaving Calgary as the term of their loan agreement between Canada and China has come to an end. (Photo by Andrew Soong/Xinhua)

Panda cubs Jia Panpan and Jia Yueyue eat bamboo leaves in the Calgary Zoo, Canada, Oct. 30, 2019. Panda cubs Jia Panpan and Jia Yueyue in Canada's Calgary Zoo will be moving to the Giant Panda Research Base in Chengdu, capital of China's southwestern Sichuan Province, in early 2020, according to the Calgary Zoo. Jia Panpan, a male, and Jia Yueyue, a female, came to Calgary city in March 2018, and they are now almost 4 years old. The panda twins are leaving Calgary as the term of their loan agreement between Canada and China has come to an end. (Photo by Andrew Soong/Xinhua)

A zookeeper provides fresh bamboo to panda stall in the Calgary Zoo, Canada, Oct. 30, 2019. Panda cubs Jia Panpan and Jia Yueyue in Canada's Calgary Zoo will be moving to the Giant Panda Research Base in Chengdu, capital of China's southwestern Sichuan Province, in early 2020, according to the Calgary Zoo. Jia Panpan, a male, and Jia Yueyue, a female, came to Calgary city in March 2018, and they are now almost 4 years old. The panda twins are leaving Calgary as the term of their loan agreement between Canada and China has come to an end. (Photo by Andrew Soong/Xinhua)

A keeper feeds panda cubs Jia Panpan and Jia Yueyue in the Calgary Zoo, Canada, Oct. 30, 2019. Panda cubs Jia Panpan and Jia Yueyue in Canada's Calgary Zoo will be moving to the Giant Panda Research Base in Chengdu, capital of China's southwestern Sichuan Province, in early 2020, according to the Calgary Zoo. Jia Panpan, a male, and Jia Yueyue, a female, came to Calgary city in March 2018, and they are now almost 4 years old. The panda twins are leaving Calgary as the term of their loan agreement between Canada and China has come to an end. (Photo by Andrew Soong/Xinhua)

A panda cub eats bamboo leaves in the Calgary Zoo, Canada, Oct. 30, 2019. Panda cubs Jia Panpan and Jia Yueyue in Canada's Calgary Zoo will be moving to the Giant Panda Research Base in Chengdu, capital of China's southwestern Sichuan Province, in early 2020, according to the Calgary Zoo. Jia Panpan, a male, and Jia Yueyue, a female, came to Calgary city in March 2018, and they are now almost 4 years old. The panda twins are leaving Calgary as the term of their loan agreement between Canada and China has come to an end. (Photo by Andrew Soong/Xinhua)