Could a panda at the National Zoo be pregnant? These clues say a baby is on the way

All eyes are on panda Mei Xiang after the Smithsonian's National Zoo released some intriguing news about her recent activity.

"Mei Xiang has been displaying subtle behavioral changes during the past few weeks," a statement from the zoo said. "They have become more pronounced in the last 24 hours."

According to the National Zoo, in the morning, Mei Xiang began to stay inside in the panda house instead of eating bamboo in the yard as she regularly does.

But what does it all mean?

Staff at the zoo declared that Mei Xiang is in her secondary hormone phase, leaving veterinarians and zoo staff keen to think she is either pregnant or experiencing a pseudopregnancy, or false pregnancy.

"When Mei Xiang’s hormone levels return to baseline, she will either give birth to a cub or her behavior will return to normal," the zoo reported.

Hormonal changes alone do not indicate that a panda is pregnant and the zoo is in the midst of searching for more clues.

"The only way to definitively determine if a giant panda is pregnant before she gives birth is to detect a developing fetus on an ultrasound," the zoo said. "Veterinarians have been conducting regular ultrasounds to track changes in Mei Xiang’s reproductive tract, but they have not seen anything yet."

But signs do point to the possibility of a baby panda in the near future.

"Mei Xiang has also started building a nest of shredded bamboo in her den and modestly adds to it at night," the Zoo said.

Whether it is a pregnancy or pseudopregnancy, the zoo says it will have the answer by the end of August. In the meantime, the staff is keeping Mei Xiang in a quiet environment, closing the panda house to the public for the time being.

Three giant pandas currently live at the National Zoo. Along with Mei Xiang are Tian Tian and their cub Bei Bei, who was born in September 2015.