Giant male panda Xiao Liwu eats a meal of bamboo at the San Diego Zoo prior to his repatriation to China with his mother Bai Yun, bringing an end to a 23-year-long panda research program in San Diego, California, US, April 18, 2019.
"We knew when we started the programme that they were not our bears and that they wouldn't be staying so that was always in our minds," the pandas' keeper, Dallas Dumont, told Reuters. Giant pandas were threatened with extinction when they were originally loaned to the San Diego Zoo by the Chinese government in 1996, in what was initially intended to be a 10-year programme to help re-establish the species. In 2016, the status of giant pandas was changed from endangered to vulnerable by the International Union for Conservation of Nature, reflecting their comeback.
Bai Yun was born in 1991 at the Wolong Giant Panda Research Center in China and was among the original cohort of bears loaned to the zoo in 1996. She has since given birth to six cubs and is considered the "matriarch" of the San Diego panda family.