A signal of hope emitted from the Smithsonian's National Zoo this morning as caretakers discovered that resident giant panda Mei Xiang (may-SHONG) may be pregnant. An ultrasound revealed tissues that indicate a baby panda could be growing, though it is too early to tell for certain whether mother Mei Xiang will come to term. Veterinarians first detected fetal tissue last week, and have have seen other encouraging signs, including developing skeletal structures and strong blood flow within Mei Xiang’s uterus.

“In the middle of a pandemic, this is a joyful moment we can all get excited about,” says Don Neiffer , chief veterinarian at the Smithsonian’s National Zoo, who conducted the ultrasound. “We are optimistic that very shortly she may give birth to a healthy cub or cubs. We’re fortunate that Mei Xiang participated in the ultrasound allowing us to get sharp images and video. We’re watching her closely and welcome everyone to watch with us on the panda cams .”

Twenty-two-year-old Mei Xiang first arrived at the National Zoo in December 2000, along with Tian Tian, who will turn 23 at the end of the month. Reproductive scientists from the Smithsonian Conservation Biology Institute (SCBI) and Zoo veterinarians artificially inseminated Mei Xiang in March with Tian Tian's frozen semen.

SCBI scientists have been closely monitoring Mei Xiang’s rising hormone levels, and since late July, she has been sleeping more, eating less, nest-building and body-licking—all signs that she is preparing for a newborn. The National Zoo reopened to the public in July with COVID-19 health precations in place, but the panda house remains closed to provide quiet for Mei Xiang as she hopefully progresses in her pregnancy. The panda team started 24-hour-a-day behavior watch on the panda cams August 14.

“At her age, Mei Xiang will be the oldest panda to give birth in the United States. We knew her chances were slim, but our dedicated team of panda professionals has been working throughout the pandemic, first to ensure a successful insemination, and, now, we hope, a successful birth," says Brandie Smith, the Zoo's deputy director. "Miracles like this inspire us and remind us of why we devote ourselves to the Zoo profession and conservation.”

Mei Xiang has given birth to three surviving cubs: Tai Shan (tie-SHON) in 2005, Bao Bao (BOW BOW) in 2013 and Bei Bei (BAY BAY) in 2015. All three of Mei Xiang's sons now live in China. As part of the Zoo’s cooperative breeding agreement with the China Wildlife Conservation Association, all cubs born at the Zoo move to China when they are four-years-old, though the current agreement will expire in December 2020.

The Zoo's research and breeding program and Mei Xiang's success as a mother have been critical in efforts to conserve the charasmatic, but severely vulnerable pandas. Currently, as few as 1,864 giant pandas surive in the wild in their native habitat throughout central China. Another 600 live in zoos and breeding centers. One of the greatest threats to the giant pandas' survival is habitat loss and destruction .

The birth of a new cub at the Zoo would be another significant victory in the fight to save pandas. The public can follow Mei Xiang's progress with updates from the Zoo via Facebook , Twitter and Instagram using #PandaStory, and the Giant Panda e-newsletter .