Visitors to the Smithsonian's National Zoo have less than five months to say their farewells to the iconic giant pandas who've been at the zoo for nearly 23 years. The two adult giant pandas, Mei Xiang (female) and Tian Tian (male), and their cub Xiao Qi Ji (male) are returning to China by Dec. 7.

An agreement between the zoo and China Wildlife and Conservation Association brought the panda pair to the U.S. on December 6, 2000. The adult pandas were supposed to stay for a decade as part of a research and breeding agreement, but the program with China was extended several times.

The once-endangered species are now designated as "vulnerable," following a population growth of nearly 17% between 2007 and 2017. The International Union for Conservation of Nature upgraded giant Pandas on the global list of species at risk of extinction, according the World Wildlife Fund. Only 1,864 wild pandas remain in the wild, mostly in China's Sichuan Province.

History of giant pandas in US zoos

Over 50 years ago, The National Zoo received its first pandas from China, Hsing-Hsing and Ling-Ling, as an effort to save the species by breeding them. The Zoo's giant panda team works closely with colleagues in China to advance conservation efforts around the world, according to the zoo's conservation biology institute.

Mei Xiang has given birth to seven cubs while at the zoo. Four of her cubs are living, and three died before adulthood. As part of the agreement with China, cubs must be returned by age 4.

When Mei Xiang gave birth to Xiao Qi Ji in August of 2020, she became the oldest giant panda to have a cub in North America.

Once the three giant pandas return to their homeland from Washington, D.C., only four giant pandas will be left in the U.S.: Lun Lun and Yang Yang, and their offspring Ya Lun and Xi Lun, all of which live at Zoo Atlanta.

The younger cubs at Zoo Atlanta are expected to travel to China in 2024, the zoo says. The adult pandas are expected to return as well, as there has been no discussion about extending the loan agreement instated in the mid-1990's, according to the zoo.

The Memphis Zoo returned their panda, Ya Ya, in April after a 20-year loan agreement with China ended, according to The Associated Press. Memphis and the San Diego Zoo, which sent two giant pandas to China in 2019, were the only other zoos in the U.S. to house pandas.

Farewell Ya Ya:Giant panda returns to China after 20 years at Memphis Zoo

A much-needed moment of pure joy:Giant panda at National Zoo gives birth to cub