"I am always optimistic. We very much hope even if we don't have pandas here, we can continue to tell the story of the animals, of the conservation success," she said on Monday. "And my dream is that we will have pandas here in the future."

With more than 2 million visitors every year at the zoo, and giant pandas tops on their wish and watch list, Smith said the absence of the bears may mean that the other animals will get "a little extra" attention.

For Bryan Amaral, senior curator of mammals at the National Zoo, giant pandas have become synonymous with the zoo, and Xiao Qi Ji is just a lot of fun, a bubbly guy, who is always active and "always keeps us on our toes".

"We'll miss them terribly, and I'm sure the community will, but they're going to a great place. And you know, like I said, it's bittersweet. We've been successful, which is why unfortunately we have to say goodbye," Amaral said.