Photo by Mehgan Murphy/Smithsonian’s National Zoo

The National Zoo once again rolled out the fanfare for superstar giant panda Tai Shan this morning, as D.C.’s favorite ball of fur (and stick of butter) turned 4. Now a teenager in “bear years,” the panda dug into a three-tiered, frozen “cake” made out of water, beet juice, bamboo and fruit that was prepared by Zoo staff. Crowds of onlookers were on hand early this morning to watch the panda dig in to his treat and wish him a happy birthday.

But Tai Shan’s 4th birthday brings with it the bittersweet reminder that the agreement between China and the National Zoo to keep the panda in Washington is soon to expire. The Zoo negotiated a two-year lease extension for Tai Shan in 2007, but the current agreement states that he must be returned to China by the end of this year.

According to Zoo spokesperson Karin Korpowski, talks with the Chinese about Tai Shan’s fate have already begun, but she cautions that it’s “a slow process.” The teenaged panda isn’t going anywhere just yet, she said, noting that no permits have yet been obtained to move him back to his ancestral home. But is the Zoo fighting to keep Tai Shan?

“The National Zoo is committed to having giant pandas,” was all Korpowski could offer. “Our goal is to always have pandas.”

In other words, if you’re partial to Tai Shan, you might want to start getting in your visits to see him over the next couple of months, before the clock starts to run out. You can also submit your birthday wishes to the panda online, and the Zoo’s entire photo gallery of this morning’s birthday celebration here. A video depicting the construction of Tai Shan’s ice cake is below.