The number of pandas at the Smithsonian National Zoo might grow by one in just a few days, officials announced on Friday: Mei Xiang appears to be pregnant.
The 22-year-old giant panda, whose name is pronounced may-SHONG, has “tissue consistent with fetal development,” according to the zoo, which cautioned in its statement that “it is too early to determine if the tissue is a completely viable developing fetus” because there is “a substantial possibility that Mei Xiang could resorb or miscarry a fetus.” The zoo said that scientists do not fully understand why some mammals resorb fetuses.
But if she is pregnant, the zoo’s veterinarians estimate, Mei Xiang could give birth within the next few days. The zoo currently has just an adult pair of giant pandas.
“In the middle of a pandemic, this is a joyful moment we can all get excited about,” said Dr. Don Neiffer, the zoo’s chief veterinarian, who conducted an ultrasound on Mei Xiang Friday morning, finding the potential fetus.
“We’re watching her closely and welcome everyone to watch with us on the panda cams,” he said.
“Veterinarians first detected fetal tissue last week, and they have since noted developing skeletal structure and strong blood flow within Mei Xiang’s uterus,” the zoo said.
Pamela Baker-Masson, the zoo’s associate director of communications and exhibits, said part of the reason the potential pregnancy is so hopeful and inspiring is Mei Xiang’s age.
“The polite way of saying it is: advanced maternal age,” Ms. Baker-Masson said during a telephone interview on Friday, explaining that if Mei Xiang gives birth, “and we think she will, she will be the oldest panda in the United States to have done so.”
Ms. Baker-Masson said the zoo is tracking down the records, but right now, they know of only one panda who gave birth at an older age, in China at 23.
Pandas are notoriously bad breeders. The animals have a mating “season” of just a few days per year, and whether in captivity or in the wild, giant pandas rarely show the desire or skill to mate, imperiling their survival. In 2014, the World Wide Fund for Nature estimated that there were only 1,864 giant pandas remaining in the wild. So whenever they do get it on, like the couple that got frisky in April in a Hong Kong zoo, it’s a big deal.
Pandas are also known to experience “delayed implantation,” meaning that a fertilized embryo may not attach to the uterine wall for weeks, or even months. The zoo said it’s unclear what causes the embryo to implant, but once it does, it grows exponentially.
Ms. Baker-Masson said it was not clear whether Mei Xiang experienced delayed implantation.
Mei Xiang, who has three surviving cubs that now live in China, was artificially inseminated with frozen semen collected from Tian Tian (pronounced tee-YEN tee-YEN), her National Zoo mate, on March 22, according to the zoo.
The zoo’s scientists confirmed “secondary rise in Mei Xiang’s urinary progesterone levels began June 10,” and “in late July, Mei Xiang exhibited behaviors consistent with pregnancy or pseudopregnancy.”
“Now, she is sleeping more, eating less, nest-building and has been observed body licking,” the zoo said.
Pandas are born helpless, weighing just a few ounces, Ms. Baker-Masson said, calling Mei Xiang “an awesome mother.”
“She really is a great mother, we have a lot of confidence in her,” Ms. Baker-Masson said. “She’s extremely attentive. She knows what to do.”