The National Zoo's giant pandas made several attempts to mate yesterday, even as animal care staff prepared to turn to artificial means to try to achieve a panda cub birth.
The celebrated panda pair were put together yesterday morning and afternoon, but their mating attempts were unsuccessful, according to zoo scientists. If "effective mating" did not occur during the night, zoo officials said, they would resort to artificial insemination this morning.
Mei Xiang, 6, in rear, and Tian Tian, 7, have tried twice before to mate.
(Robert A. Reeder - The Washington Post)
Last night, zoo spokeswoman Peper Long said the latest test results show that Mei Xiang's hormone levels are dropping, meaning that she is at peak fertility.
"In past years, they've shown excellent sexual behavior but have been a bit out of sync," Lisa Stevens, the zoo's assistant curator for giant pandas, said yesterday. "We're very concerned about the lack of synchrony."
Translation: The male giant panda is eager, Stevens said, but has "alignment" problems; the female cries out to him loudly and displays other come-hither behavior, but then lies flat on her stomach.
The Panda House was closed to visitors and media yesterday and will remain off-limits while breeding attempts are underway. Those wanting to follow the annual mating ritual had to rely on a webcam, viewed from the zoo's Web site at www.nationalzoo.si.edu.
Stevens said the closure was not to give the animals privacy -- they scarcely notice the crowds -- but to make it easier for the zoo staff to collect behavioral data, particularly recordings of the sounds giant pandas make during breeding season.
The pandas, female Mei Xiang (pronounced may-SHAWNG) and male Tian Tian (t-YEN t-YEN), were separated last week for the first time during breeding season. Zoo officials said this breeding manipulation has been used successfully in China and helps stimulate sexual interest and coordinate mating behavior.
The National Zoo has been trying for decades to achieve a successful cub birth. Its first panda pair, Ling-Ling and Hsing-Hsing, produced five cubs, but none lived more than a few days. There has not been a panda cub birth at the zoo since 1989.
Mei Xiang, now 6, and Tian Tian, 7, arrived from China in 2000. They have gotten along very well and mated for the first time, very briefly, in April 2003. But no pregnancy resulted. When the pair failed to mate last year, zoo scientists tried artificial insemination, without success.
Jo Gayle Howard, a reproductive scientist at the zoo who has been involved in efforts to breed its pandas since 1980, said zoo staff has been steadily acquiring additional knowledge about the highly endangered species.
"We have learned a lot about giant pandas," she said. "All of us know a lot more."
Howard, Stevens and Sharon Deem, a zoo veterinarian, answered questions yesterday about the latest mating efforts.
Howard said zoo scientists have developed a way to test the level of Mei Xiang's hormones to pinpoint peak fertility. The zoo has a special hormone-testing lab at its Conservation and Research Center in Virginia but has moved a mobile lab to the main zoo, in Northwest Washington, to get test results faster.
There is only about a two-day window for optimal mating. This, Howard said, poses a unique challenge in panda breeding. The zoo wants to give Tian Tian and Mei Xiang as much time as possible to mate. But it cannot wait too long to perform artificial insemination, which Howard said has been successful in China about 60 percent of the time.
"Saturday would be too late," she said.
The San Diego Zoo is the only facility in the United States to breed surviving giant panda cubs. Of the two births, the first was achieved by artificial insemination.