The 3 remaining pandas have left the National Zoo. Why China is taking all its pandas back.

It’s the end of an era for so-called panda diplomacy.

The National Zoo’s three giant pandas — Tian Tian, Mei Xiang and Xiao Qi Ji — left Washington, D.C., early Wednesday and were taken to Dulles International Airport in northern Virginia, where they were boarded onto the specially equipped Boeing FedEx Panda Express to begin their long trans-Pacific flight to Chengdu, China, their new home.

According to the zoo, the pandas are traveling with approximately 220 pounds of bamboo, 8 pounds of leaf-eater biscuits, 5 pounds of low-starch biscuits, 6 pounds of apples, 5 pounds of carrots, 6 pounds of sweet potatoes, 3 pounds of sugar cane, 1 pound of pears and 1 pound of cooked squash for the 19-hour flight, which will include a refueling stop in Anchorage, Alaska.

Speaking outside an empty panda enclosure, National Zoo director Brandie Smith called it a "hard morning."

End of an era

Tian Tian the panda
Tian Tian at the National Zoo in Washington on Tuesday, the final day of viewing before being returned to China. (Jim Watson/AFP via Getty Images)

It’s the first time in 23 years the zoo has been without pandas, which have been a fixture there since 1972, when China gifted two pandas to the National Zoo as a gesture of goodwill during President Richard Nixon’s administration.

Since then, zoos across the country have hosted giant pandas for years at a time. But that practice is coming to an end.

And soon, there will be no pandas in the United States.

Zoos in Memphis and San Diego have already returned their pandas to China. And the only other pandas in the country, at Atlanta’s zoo, are set to be returned later this month.

In 2024, for the first time in more than 50 years, there will be no pandas in the United States, after zoos in Atlanta and Washington, D.C., return theirs to China — which has been loaning its pandas to countries for decades.

Why are they being returned?

Tian Tian the panda en route to Dulles International Airport on Wednesday
Tian Tian the panda en route to Dulles International Airport on Wednesday. (Stephanie Scarbrough/AP)

Usually, the Smithsonian Institution — which operates the National Zoo — renews its panda contracts in order to keep them. But this year officials say such attempts have failed.

Smith said the zoo remains committed to its panda conservation program, and “we look forward to celebrating with all of you when pandas can return to D.C.”

Did you know? Giant pandas are China’s national animal. Their life expectancy in the wild is about 15 years, but in captivity they have lived to be as old as 38.

Back in April, Ya Ya, a giant panda that had spent 20 years at the Memphis Zoo, was returned after the zoo's loan agreement ended without renewal.

Allegations of neglect against the Memphis Zoo were circulated on Chinese social media, which the zoo emphatically denied.

Meanwhile, Ya Ya’s trip home was closely followed online in both the U.S. and China as her fans in both countries tracked her flight from Memphis to Shanghai.

“An image from Chinese broadcaster Phoenix News was particularly popular among Chinese social media users,” the Associated Press explained at the time. “It showed Ya Ya relieving herself before the trip and leaving the poop as a present for the zoo.”

What about other countries?

Xiao Qi Ji plays at his enclosure at the Smithsonian National Zoo in Washington, D.C., on Sept. 28. (Jose Luis Magana/AP)
Xiao Qi Ji plays at his enclosure at the Smithsonian National Zoo in Washington, D.C., on Sept. 28. (Jose Luis Magana/AP)

Several countries around the world have pandas on loan from China that are also due to be returned when their agreements expire.

Officials in Singapore announced that a giant panda cub named Le Le will be returned to China in December. A farewell event for the 2-year-old is set for Nov. 20.

Similar celebrations were held for Xiang Xiang, a 5-year-old panda who was returned to China from Tokyo's Ueno Zoo in February, and Fan Xing, a 3-year-old panda who was returned to China from a zoo in the Netherlands last month.

A giant panda on loan from China died suddenly in a zoo in northern Thailand in April, six months before she was due to return home.

In July, two new pandas were born in South Korea, but they are considered the property of China and will soon be returned too.

More panda coverage on Yahoo News

The FedEx Panda Express taking off from Dulles International Airport with giant pandas Xiao Qi Ji, Tian Tian and Mei Xiang on board for their return trip to China
The FedEx Panda Express taking off from Dulles International Airport with giant pandas Xiao Qi Ji, Tian Tian and Mei Xiang on board for their return trip to China. (Julia Nikhinson/Reuters)