National Zoo closely monitors Mei Xiang panda

It was not a manic Monday at the national zoo, quite the opposite.

It all started when the little Bei Bei panda, about three years old, came out of his burrow for a stroll.

"It's so cute, it's adorable," said Emma Umakapar, age 9, visiting New Jersey. "I feel like I want to have him as a pet."

Bei Bei wandered, seemingly oblivious to the clatter and clatter of camera shutters, and smashing smartphones.

He dipped his feet in a children's paddling pool, climbed onto a tree, and then calmly returned to his lair.

"I'm a big fan of panda," said visitor Gina Koo. "I'm all about pandas, my free time is spent watching panda videos, looking at the panda camera here."

Indeed, a wave of excitement spread across the panda fandom that day, with the word that Bei Bei's mother, Mei Xiang, could wait again.

Panda-monium, indeed.

"She builds a nest, she sleeps a lot, food consumption is going down," said Laurie Thompson, assistant of the National Zoo's giant panda. "Do a lot of grooming, body grooming, which is all they do when they are getting close to delivery."

RELATED: Smithsonian National Zoo: Panda House closed for possible pregnancy of Mei Xiang panda

Zoo officials warn that it could be a "pseudo-pregnancy", with all the telltale signs of a future mom, but without the reality.

Mei Xiang undergoes daily urine tests.

But it's a biweekly ultrasound that will determine if a little one is en route.

"If they see a teddy bear on ultrasound, then we know she's pregnant," Thompson said. "We'll finally do a 24-hour surveillance on her and watch her, look for signs of impending birth, having contractions and things like that."

The possible pregnancy would be the fourth delivery for Mei Xiang, who will turn 20 on July 22.

Experts say giant pandas tend to breed until their early twenties.

RELATED: Smithsonian zoo experts monitor giant Mei Xiang panda for possible pregnancy

Visitors to the zoo say that a new little panda in the nation's capital would be irresistible.

"Incredible, absolutely incredible," said Belina Knapp, of Rochester, New York. "One of my favorite animals, who does not like baby pandas?

Not so long ago, Bei Bei was the newcomer.

He was born on August 22, 2015 with a twin who died four days after birth.

His tiny pink body was smaller than a finger.

At just a few ounces, he was 1/900 of his mother's weight.

"The babies are very small, they are hairless," said Thompson. "They are blind when they go out, so they do not do much inside, it's more when they are finally born."

Zoo officials say Mei Xiang may have conceived in March.

She gets a lot of rest and calm, and her section of the panda show is closed.

Now, the wait begins.

"It's good to have more pandas around, so the population will grow bigger," Umakapar said.

The zoo says that if Mei Xiang is really pregnant, the new baby could make an appearance in late July.

Panda fans keep their fingers crossed.

"I'm really very optimistic that she's pregnant this year," Koo said. "It would be wonderful for her, because she's such a great mom."