"The 15-year Sino-Danish Panda International Research Cooperation Project officially began today. The two sides will start cooperation and research in the fields of giant panda breeding, animal behavior and protection education, and will jointly promote protections of endangered wildlife such as giant pandas," Zhang Zhihe, director of the Chengdu Research Base of Giant Panda Breeding, told Xinhua.

Male Xing Er, a 5-year-old, and female Mao Er, a 4-year-old, left the southwestern Chinese city of Chengdu on April 4 and headed to their new home at Copenhagen Zoo.