Zoo officials said Thursday the cub's gender was determined during an exam by the zoo's veterinary team and a colleague from the Chengdu Research Base of Giant Panda Breeding in China.
The cub, which will be named later, became available for examination after his mother, Lun Lun, began leaving him for brief periods to eat and drink.
Zoo officials say the cub weighs just over 11 ounces and has begun to develop the distinctive coloration of black saddles on the shoulders and black patches over the eyes. They say his eyes are not yet open.
Giant pandas are an endangered species, and the cub is the only one born in a U.S. zoo this year.