Saying goodbye to the pandas at Zoo Atlanta

So it is with the romance between Atlanta and two big black-and-white bears.

Today, May 12, the furry siblings Xi Lan and Po will leave Zoo Atlanta and travel to the Sichuan province in China to live at the Chengdu Research Base of Giant Panda Breeding.

Some of their fans are already experiencing separation anxiety.

“I can hardly bear the thought,” wrote Jennifer Purdy-Lynn on Zoo Atlanta’s Facebook page.

“They are part of the family,” said Rebecca Snyder, curator of mammals at the zoo. “It is hard to see a cub born here, who you’ve watched grow up its whole life, it’s hard to see them go.”

Like all of the pandas at Zoo Atlanta — even the ones not yet born — Xi Lan and Po are the property of China, home of the last remaining panda habitats. The pandas’ parents, Lun Lun and Yang Yang, also belong to the Chengdu center, and are in Atlanta on loan, through an arrangement that is renegotiated every five years or so.

They have been a prolific pair. Their offspring include Mei Lan, born in 2006; Xi Lan, from 2008; Po, from 2010; and the twins, Mei Lun and Mei Huan, born last year.

Xi Lan, 5, and Po, 3, were scheduled to be transferred to China last fall, but veterinarians determined they weren’t quite chunky enough to make the trip in good health.

“We wanted them to be fat and sassy, ” said Deputy Director Dwight Lawson. The zoo staff decided to postpone that trip until this May. Since that time, the pandas have each put on about 22 pounds, and Xi Lan, at 220, and Po, at 187, are now at traveling weight.

Veterinarians discovered something else during those same examinations: Po was not a boy. The panda had been named after the lead character in the animated movie “Kung Fu Panda,” in a ceremony presided over by actor Jack Black, who provided the voice for the cinematic panda.

During the same series of examinations, zoo officials also discovered that the twins, previously believed to be males, were, in fact, also female. The surprise reveals reminded panda fans that Zoo Atlanta’s first cub, Mei Lan, also switched camps, after she was examined in China, and it was determined that she was a male.

The lesson learned then was that it’s notoriously difficult to determine pandas’ gender. “They are covered up in fur, and you really can’t look and they don’t want you to look,” Lawson said.

(The zoo used blood tests for absolute certainty.)

Kenn Harwood, lead keeper of carnivores, and Sam Rivera, zoo veterinarian, will travel with the pandas during the 40-hour trip to make sure they are well cared-for. They will change planes in Inchon, South Korea, before flying to Chengdu.

The keepers will be packing a lunch (and dinner) for the bears in the form of 300 pounds of bamboo, plus several high-nutrition bear biscuits.

While zoo keepers hate to see the pandas go, their quarters would have become crowded in a short while. Adult pandas are solitary animals, and each needs his or her own enclosure. That would have meant six different enclosures for the panda family, after the twins are weaned.

Metro Atlantans can bid the animals goodbye any time in the coming week and a half. The morning is the best time for panda viewing.