The new giant panda cub at the National Zoo is "healthy, active, and vibrant," according researchers who finally got to examine the newborn for the first time this weekend. Mei Xiang, the zoo's female giant panda, gave birth to the 4.8 ounce cub on Friday. "The cub is robust, fully formed, and is a bright, healthy shade of pink," the National Zoo explains. Keepers won't know the gender of the new cub for a few weeks.

Mei Xiang also gave birth to a second, stillborn cub on Saturday. The emergence of the second cub led to a frightening case of mistaken identity for zoo keepers, because the second birth went unnoticed on video feeds from the panda's den. When keep, the zoo staff scrambled in "five minutes of pure terror" and "full-blown panic" as they thought Friday's seemingly healthy cub was dead. Then, keepers heard the squeals of the first cub, tucked safely under its mother's arm.

(photos: The National Zoo/AP)

The healthy cub is eating and digesting food, has a steady heartbeat, and what appear to be properly functioning lungs. Researchers are going to try to examine the cub again on Tuesday — which isn't as easy as it sounds. Mei became, understandably, agitated when researchers took her cub away this morning.

The healthy cub is the third for Mei. her only other surviving cub was born in 2005. Almost a year ago, she gave birth to a cub, not fully developed, who died six days later.