Bei Bei the giant panda leaving the National Zoo for China

Washington — The National Zoo in Washington, D.C., is saying goodbye to Bei Bei. He's the last of its beloved giant panda cubs, and his departure could mean the end of an era. 

For the past four years, we've watched as Bei Bei has melted hearts, as he snuggled and played with his mother and somersaulted down snowy hills.

Laurie Thompson at the National Zoo has been watching over Bei Bei since the day he was born. But now, at 4 years old, he's all grown up, and under an agreement with China, he must join their panda breeding program.
  
Thompson gave CBS News a sneak peek as she acclimated him to a steel crate like the one that will carry him to China Tuesday aboard a FedEx plane with his picture on the side.
 
"Once I have to say goodbye that's going to be tough," Thompson said.

Bei Bei is the last panda cub at the National Zoo. His older brother and sister are already in China. His parents will remain in D.C., but they are probably past breeding age and it's unclear if China will send another breeding pair.
 
Zoo Director Steve Monfort believes this is just a temporary pause.
 
"We started 47 years ago with giant pandas. Our vision would be continuing working with the Chinese counterparts for another 50 years if we can," he said.

There are only about 1,800 pandas left in the wild. The hope is that Bei Bei will soon become a father and play his role in assuring that this vulnerable species never disappears.

In:
• China