Scoot on over here, cutie! Xiao Liwu, the San Diego Zoo’s 4-month-old panda cub, was "very busy" during his latest exam. He's walking now, making it a little harder for the zoo's veterinarians to take his measurements. In fact, he did so much exploring during his exam that he exhausted himself, and cuddled up into a little ball to rest at the end.

Once his keepers are satisified that he's mastered walking, he and his mom will get access to a public exhibit.