WASHINGTON -- Surprise news came late Saturday from the National Zoo in Washington: a female giant panda gave birth to not one, but two cubs.
Zoo spokeswoman Pamela Baker-Masson confirmed in an email that Mei Xiang gave birth to the first cub at 5:35 p.m. The zoo sent a tweet announcing the second arrival, which came at 10:07 p.m.
Mei Xiang's first cub, Tai Shan, was born in 2005. Her second cub, Bao Bao, turns 2 years old on Sunday.
Keepers will be watching the newest cubs closely. Pink, hairless and blind, newborn cubs weigh three to five ounces and are about the size of a stick of butter.
The zoo has also had disappointments in the past. Mei Xiang gave birth to another stillborn cub in 2013. And in 2012, she gave birth to a cub that died after just six days. Its lungs hadn't fully developed.
Even if the new cubs are healthy, panda fans shouldn't expect to see them in person for a while. After Mei Xiang's second cub Bao Bao was born in 2013, it was about five months before she made her public debut. Fans who want to see the newest panda will have to try to catch a glimpse of them on the zoo's online panda cam.
The public also won't learn immediately whether the cubs are male or female or whether the zoo's male panda, Tian Tian, are the cubs' father. It takes time to determine the tiny cubs' genders and Mei Xiang was artificially inseminated with sperm from Tian Tian and a panda named Hui Hui from Wolong, China, who was determined to be one of the best genetic matches.
The National Zoo is one of only four zoos nationwide to have pandas, which are on loan from China. But the Washington pandas have a history that makes them closely watched.
The zoo's first pair of pandas, Ling-Ling and Hsing-Hsing, were a gift from China following President Richard Nixon's historic 1972 visit to the country. The pair had five cubs while living at the zoo but none survived.
The zoo's current pandas, Mei Xiang and Tian Tian, the parents of both Bao Bao and Tai Shan, arrived in 2000. The pandas belong to China as do any cubs they have. The pair's first cub, Tai Shan, returned to China in 2010. Their second cub, Bao Bao, still lives at the National Zoo.