WASHINGTON - One year ago, he was nearly hairless, pink and weighed about four ounces, less than most bagels. On Sunday, his first birthday, giant panda Tai Shan is an active, 56-pound cub and the star attraction of the National Zoo.

"He's like a rambunctious little toddler that loves to get into everything," said Dr. Suzan Murray, the zoo's chief veterinarian.

Murray has monitored every developmental benchmark for the black and white panda since his birth on July 9, 2005. Those included the opening of his eyes, the development of his distinctive markings, his heartbeat, his mobility, and even the frequency of his squeals, grunts and barks.

The cub still nurses, but he has advanced from milk provided by his mother, Mei Xiang, to eating bamboo. The woody perennial grass is the staple of adult pandas' diets, accounting for more than 90 percent of their nutrition.

"My next challenge is weaning Tai Shan from his mom," said Lisa Stevens, the zoo's curator of pandas and primates.

For his birthday, staffers prepared a giant fruitsicle for the cub, a frozen melange of apples, yams, carrots and fruit juices. That is a favorite of Mei Xiang's, but this was the first prepared for the growing cub.