The panda, 20-year old Bai Yun gave birth to her sixth cub since arriving at the San Diego Zoo, considered the most pandas born at a breeding facility outside the endangered species' native China.
A team of researchers observed Bai Yun deliver the baby cub, around 2:10 p.m., while watching the Zoo's closed circuit camera mounted inside the birthing den, according to San Diego Zoo officials.
Bai Yun is one of the oldest giant pandas known to give birth. This is the sixth cub born at the San Diego Zoo, the most born at a breeding facility outside of China. All six giant panda cubs have been born to Bai Yun, according to San Diego Zoo officials.
Newborn giant panda cubs are born pink and grey, without sight, and weigh an average of four ounces. Their trademark black-and-white markings develop within the first months.
The sex of the cub will not be known until animal care staff can examine the cub, which is expected to happen within two months.
The zoo's panda team -- made up of researchers, veterinarians and keepers -- assembled in the morning as labor began. A panda was born at 2:10 p.m., wrote Megan Owen, conservation manger at the zoo's Institute for Conservation.
"We are still watching her and can't stop smiling," Owen said.
Congratulations poured in over Twitter, including a message from the Phoenix Zoo.
Bai Yun's last cub, Yun Zi, was born in 2009. Yun Zi means "son of cloud": Bai Yun is "white cloud."
Pandas typically weight about 100 grams at birth -- similar to a stick of butter. The zoo's hands-off approach on Sunday meant the new cub was not weighed.