It has been a busy 24 hours for giant panda researchers at the San Diego Zoo.
Early Wednesday, just before 5 a.m., the team was glued to the zoo's closed-circuit camera placed inside Bai Yun's birthing den as they watched the giant panda give birth to her fifth cub.
Even though the cub is number five, it's "just as exciting as our first," said veterinarian Meg Sutherland-Smith.
The gender of the baby is not known. Researchers won't be able to get their hands on the pink, tiny and hairless cub until several weeks from now when Bai Yun feels comfortable enough to start regularly leaving the birthing den.
As long as the mother appears to be caring for the new cub as she has her previous cubs, zoo staff will not intervene.
The zoo announced last week that Bai Yun was pregnant. Using a thermal camera and an ultrasound, zoo staff spotted images confirming that she was expecting. Ultrasound video clearly showed a tiny little panda, conceived naturally in April, moving its paws and tucking its head in.
Mother and cub are likely to remain in the birthing den, off and on, for the next four months. You can watch them through the zoo's panda cam online.
San Diego was caught up in panda-mania in 1999 when Hua Mei, Bai Yun’s first club, was the first giant panda cub to be conceived by artificial insemination and the first American-born panda cub to survive to adulthood.
She is now in a breeding program in China along with her brother, Mei Sheng, who was born in San Diego in 2003 through natural breeding. Two of Bai Yun's other offspring, Su Lin and Zhen Zhen, born in 2005 and 2007 respectively, remain at the San Diego Zoo.