ULTRASOUND INDICATES PANDA PREGNANCY

JULY 28, 2005

Through the use of ultrasound, the San Diego Zoo's giant panda team is able to confirm that the giant panda female, Bai Yun, is pregnant.

On July 18, two heartbeats were detected through ultrasound images, however, the research staff wanted to see the two fetuses before announcing a pregnancy. During an ultrasound Tuesday, July 26 veterinary staff observed both fetuses. "We are tremendously excited to be able to document the behavioral and physiological changes of a pregnant giant panda via ultrasound and thermal imaging again," said Don Lindburg, Ph. D., the San Diego Zoo's giant panda team leader. "The research community is gaining a great deal of knowledge regarding giant panda reproduction through this type of documentation while at the same time we are aiding in the population growth of a critically endangered species."

Researchers are cautious regarding a possible birth of twins because not enough has been documented to determine how often more than one fetus makes it to parturition. The viability of the second fetus is in question because its development is not equal to the first fetus. During Bai Yun's pregnancy in 2003 two fetuses were detected but only one cub, Mei Sheng, was born. It is believed the second fetus was resorbed in the womb, a process that might be very common in giant pandas. Almost half of panda births are twins while the other half is a single cub.

The giant panda team estimates implantation occurred about 7 to 8 weeks ago. Impending birth is predicted on the basis of behavioral, hormonal and anatomic changes. Giant pandas routinely delay the implantation of the fetus as much as 2 to 3 months.

The research team has been monitoring Bai Yun's behavior since the mating season in April when Bai Yun mated naturally over the course of a three-day estrus with the male panda Gao Gao. Keepers will begin a 24-hour birth watch Friday.

Since July 15, Bai Yun has remained in an off-exhibit habitat where she has slowly been showing signs of a pregnancy including changes in her hormone levels, nest building and a loss of appetite. Most recently her mammary glands have swollen and she is almost exclusively spending her time indoors and in the den.

Bai Yun is 13 years old and has given birth twice before. The first time was Aug. 21, 1999, when a female cub, Hua Mei, was born at the San Diego Zoo's Giant Panda Research Station. Hua Mei was the first surviving giant panda to have been born in the United States. She is now in the People's Republic of China as part of the giant panda breeding and conservation program and gave birth to twins last year. The second cub Mei Sheng, a male panda born Aug. 19, 2003, is still at the San Diego Zoo.

The 100-acre San Diego Zoo is operated by the not-for-profit Zoological Society of San Diego. The Zoological Society, dedicated to the conservation of endangered species and their habitats, engages in conservation and research work around the globe. The Zoological Society also manages the 1,800-acre San Diego Zoo's Wild Animal Park (more than half of which has been set aside as protected native species habitat) and the department of Conservation and Research for Endangered Species (CRES), and is working to establish field stations in five key ecological areas worldwide.