Bai Yun, a 21-year-old panda at the San Diego Zoo, gave birth to a panda cub recently on the afternoon of Sunday, July 29. Zoo It was considered a miraculous birth because of her advanced age and the fact that Bai Yun had an unsuccessful pregnancy last year. The new panda is Bai Yun’s sixth, which is a record for the endangered panda species born in captivity.

Bai Yun and Gao Gao, her 20-year-old regular mate with whom she’d previously had four cubs, are at the San Diego zoo through next year as part of a loan program with China. The cub, who now weighs about 4 ounces, will not be named until it is 100 days ago. The name of the new baby will then be determined via an online poll. The mother and baby will be sequestered for five months in her den and kept under observation through a “Panda Cam.” The sex of the baby will not be determined also until zoo keepers can actually examine the youngster at around 100 days old.

Prior to the birth, Bai Yun’s medical team earlier this month conducted an ultrasound, to better help them determine if Bai Yun was pregnant. This was after they suspected she was on the basis of hormone testing and behavioral observations. A new device called a forward-looking infrared camera (FLIR) — helped zoo staff determine that Bai Yun was indeed expecting. This camera was originally developed for military testing.

Zoo veterinarians say that the weekly ultrasound testings on Bai Yun have also enabled them to learn more about panda pregnancies and fetal growth rates. Only about a week before Bai Yun gave birth was the zoo staff able to detect a heartbeat. At that time, the zoo’s director of reproductive physiology, Barbara Durrant, was concerned that things were not looking so good. So it was with great joy and celebration that the birth of the Bai Yun’s new baby was announced.