Atlantans formed long lines Sunday at Zoo Atlanta, waiting for a last look at giant panda twins Mei Lun and Mei Huan.

On Thursday, Nov. 3, the 3-year-old bears, the first set of giant panda twins ever reared in the United States, will board a cargo plane bound for the Sichuan Province in China, where they will be relocated to the Chengdu Research Base of Giant Panda Breeding.

“Zoo Atlanta is proud and honored to have been Mei Lun’s and Mei Huan’s stewards for their first three years,” said Raymond B. King, president and CEO.

King said it is “bittersweet” to see the twins go, but satisfying to know that Zoo Atlanta has done its part to help in the preservation of the species.

The last official opportunity to view the female pandas at their Atlanta home is Tuesday, Nov. 1. They may appear briefly Wednesday, Nov. 2, before they enter their specially designed crates on Thursday.

Their flight to China will make two stops in the U.S., and they will change planes in South Korea. With the 8.5-hour layover in South Korea, the trip will take about 38 hours.

Dr. Sam Rivera, senior clinical veterinarian at the zoo, and Kenn Harwood, assistant curator of mammals, will travel with the pandas to China, along with two pallets of bamboo, sugarcane, bananas, apples, biscuits and sweet potatoes.

“They really love sugarcane,” said Hayley Murphy, director of veterinary services. “All their favorite treats will go with them.”

The pandas, born July 15, 2013, have been practicing walking in and out of their crates for the past several weeks, and are now accustomed to the interior, Murphy said.

The female twins are the fourth and fifth offspring of Lun Lun and Yang Yang, who were loaned to Zoo Atlanta in 1999. The conditions of the loan included the stipulation that the offspring of the couple will all eventually go to China.

Mei Lun and Mei Huan's three older siblings traveled to the Chengdu facility in 2010 and 2014, and made the daylong trip without incident, Murphy said. The motion of the airplane and the trucks seems to lull them into a sleepy state.

Murphy said Rivera will have anti-anxiety drugs on hand, in case they are needed, but said that the drugs weren’t necessary for the older siblings.

Fewer than 1,900 giant pandas are estimated to remain in the wild in China’s Sichuan, Shaanxi and Gansu provinces. Deforestation and habitat fragmentation pose an ongoing threat to the species. More than 1,200 of China’s remaining wild giant pandas live inside nature reserves, eight of which are supported by Zoo Atlanta.

According to Zoo Atlanta spokesperson Rachel Davis, the zoo has contributed over $10 million in sustained support for wild giant pandas.

Mei Lan, the twins’ oldest brother, is the father of seven cubs at Chengdu. Mei Lun and Mei Huan won’t reach breeding age for several years.

Panda fans can keep up with the twins and their siblings on the Panda Cam, and on Zoo Atlanta's Facebook page, where one reader posted, "Please tell me that some of our Zoo Atlantans can Skype or travel to see them sometime!!!"

In a Facebook Live posting last week, the zoo answered some questions about the pandas, and one listener wondered whether the mother, Lun Lun, will miss her twins.

Stephanie Braccini, curator of mammals, explained that pandas are solitary creatures, and the twins have been living apart from their mother since 2015. (You can see them at play in the YouTube video above.) In addition, Lun Lun is busy with her second set of twins, born Sept. 3. The youngest cubs have remained behind the scenes, but will make their public debut sometime in the next two months.