Mei Xiang enjoying a fruitsicle at the zoo in 2012. (Photo by Daniel Reidel)

Well, is she or isn’t she?

Giant panda Mei Xiang is exhibiting all the signs of a second hormone rise in a pregnancy—she’s building a nest in her den, eating less, sleeping more, and reacts strongly to loud noises, according to the Smithsonian National Zoo.

But just because hormones are on the ascent for the mother of Bei Bei, Bao Bao, and Tai Shan, a new panda cub won’t necessarily follow.

Pandas are one of the mammals (most likely including Cersei Lannister) that can experience pseudopregnancies, also known as “fake” or “phantom” pregnancies, in which the body exhibits all of the physical signs of gestation without actually having a bun in the oven.

Still, though, zookeepers are partially closing the David M. Rubenstein Family Giant Panda Habitat to keep Mei Xiang’s den quiet as part of an abundance of caution. Outdoor habitats and viewing areas remain open, but Bei Bei’s indoor viewing is temporarily off-limits. (While the two-year-old panda will have access to the outdoors until 2 p.m., the zoo recommends scoping out the yard from 8-10 a.m. for the best chance at seeing him.)

And there’s certainly a chance that Mei Xiang is pregnant, even though she and the Smithsonian National Zoo’s male panda, Tian Tian, did not have sex this year (and haven’t ever figured out how exactly to naturally do the deed, despite trying since 2000). Instead, keepers performed two rounds of artificial insemination on the 18-year-old panda using Tian Tian’s semen back in May. That same method resulted in the births of Bei Bei, Bao Bao, and Tai Shan.

Giant panda pregnancies can range in duration from about three to six months because the species can exhibit delayed implantation. The second hormone rise occurs after the implantation. Once that happens, pandas give birth in 40-50 days. If it’s a pseudopregnancy, her hormone levels will return to normal after that time period as well, only sans cub.

Previously:
The Zoo’s Giant Pandas Did Not Have Sex This Year
Giant Panda Mei Xiang Might Be Ready To Breed Soon At The National Zoo
Giant Panda Tian Tian Is Feeling Horny, Restless