From kicking back while munching on bamboo to watching their roly-poly bodies tumbling on the ground, giant pandas are an iconic attraction at the San Diego Zoo. But now visitors are lining up for a last look at the adorable black-and-white animals, reports CBS News correspondent Jamie Yuccas.

Zookeepers Dallas Dumont and Kathy Hawk have cared for the pandas for years.



It was 1996 when Bai Yun arrived from China. At the time, pandas were endangered, so Chinese authorities asked the zoo to help save the species from extinction. But when the breeding program began, Bai Yun and her proposed mate didn't have a magic moment.



"Bai Yun was very much interested in him, but he had nothing to do with her," Hawk recounted with a laugh. "She flirted with him. She would sometimes roll in the dirt and rub her face in the dirt… thinking she looked very pretty. And she'd go trotting up to him and he'd just go, 'Whoa' … and he'd just run from her."

So Barbara Durrant, the zoo's director of reproductive sciences, employed artificial insemination. It was successful, and research to decipher the mysteries of panda mating habits began. However, the length of a pregnancy remains a guessing game.

"We've had pregnancies reported as short as 85 days and as long as 185 days," Durrant said. "The physiology is still a little bit mysterious."

A giant panda at the San Diego Zoo. CBS News

Luckily, Bai Yun's second suitor, Gao Gao, won her over.

Pandas are unable to see or hear at birth. As cubs learn to climb, it's not unusual for them to take a spill – something the keepers discovered only when it first went down.

"We literally heard a collective [gasp] from the whole group in the panda exhibit," Dumont said. "And everyone was just beside themselves. And he shakes himself off, kinda looks around like, 'Oh, I hope nobody saw that' and then back up the tree."

Xiao Liwu was their sixth cub. "CBS This Morning" was first to meet the adorable ball of fluff back in 2013.

Whether born here or abroad, all pandas belong to China. The zoo said successful breeding and an increased awareness of conservation helped boost the wild population of pandas in China to around 2,000, downgrading the panda from "endangered" status to "vulnerable" in 2016.

Building bonds of trust with the pandas has allowed zookeepers to perform some medical tests without having to subject the animals to anesthesia. It's also helping them crate-train the pandas for their journey back to China. Their new home will be the Chinese Conservation and Research Center, where other former San Diego pandas now live.



At 27, Bai Yun's breeding days are over. But that doesn't make it any easier for those who love her to say goodbye.

"Is it almost... like this is your child and they're leaving for college?" Yuccas asked.

"Absolutely. Particularly with Bai Yun… We've been with every baby that she's had. We've held every cub that she's had," Hawk said. "So she is like our daughter, more or less, and then the cubs are our grandkids. … And I can't top that."

"Yeah, she's our baby," Dumont agreed.



The panda exhibit will stay up even while it's empty. San Diego Zoo administrators are planning to travel to China to continue negotiations for new cubs in the future, because after so long, having pandas at the San Diego Zoo has become a "bear" necessity.