WASHINGTON, DC (WUSA) -- There is a feeling of guarded optimism at the National's Zoo's giant panda exhibit. The female panda, Mei Xiang, may be pregnant.
Her hormone levels are up and she is showing all the signs of pregnancy: licking her paws, cradling a favorite object, building a nest, eating less bamboo, and keeping very quiet to conserve energy.
But then, we've been here before. "It's really hard to tell if pandas are pregnant," says Nicole MacCorkle, Animal Keeper for the giant pandas. She says a pseudopregnancy will create the same symptoms as a real pregnancy in pandas.
After Mei and her companion, Tien Tien, failed to successfully mate last winter, zoo scientists artificially inseminated her on January 30th. Panda gestation usually takes between 90 and 185 days. It's been 120 days and Zoo keepers are hopeful.
They've added volunteers around the clock on a 24-hour watch on the LIVE CAMERAS, and they are "den training." That is a practice in which they give Mei Xiang something she likes, such as a pear, then take it away and give it back.
They want to build up her trust so that she will allow them to take a cub away for supplemental feedings, knowing that they will give it back. This would be most beneficial if she happen to have twins.
Giant pandas have a 60% chance of having twins. But the money only feeds the strongest in the wild. In captivity, the practice is to feed them both, swapping them out for extra feedings. But if it's just one cub, like Tai Shan, born to the same couple in 2005, they may just let Mei Xiang do her thing.
"She's a fantastic mother. We know she would do a great job again," said MacCorkle.
Thirty-four-year volunteer Helen Gual remembers the birth of the cub called "Butter Stick." She says it appeared that the baby just shot out and Mei Xiang looked down wondering what it was. "Then she picked it up and started cradling it. And she didn't put it down for weeks!"
Written by Peggy Fox