When the National Zoo reopened on Wednesday morning after four-day closure due to the heavy snowstorm, giant panda Tian Tian was playing with a plastic crate in the snow-covered yard, drawing the attention of visitors taking pictures with their cameras and iPhones.

The 18-year-old, 264-pound male panda became a social media sensation in recent days when the National Zoo sent a tweet of him rolling down a snowy slope in the yard.

Laurie Thompson, giant-panda biologist at the National Zoo, said she was surprised the video went viral but not surprised at Tian Tian.

"Because that's something he does all the time," Thompson said. She described Tian Tian as "a kind of laid-back guy, but he also goes rolling down the hill. He is Mr. Outgoing."

Pandas love snow and adapt to it, according to Thompson.

In another yard, Bao Bao, a 29-month-old female giant panda, was sitting on a tree trunk, chewing on bamboo twigs.

Mei Xiang, the mother of Bao Bao and another panda cub Bei Bei, was inside the panda house. "She is busy being a mom," Thompson said.

The 5-month old male Bei Bei was kept inside the panda house, and Thompson said he will be allowed in the yard once the snow is gone.

While the zoo was closed from the afternoon of Jan 22 to Tuesday, zoo staff members worked into the evenings.

Brandie Smith, associate director for animal care sciences at the zoo, said the zoo had been fully prepared for the blizzard.

"The biggest challenge is that we cannot not come to work," she said, adding that there are 3,000 animals to be taken care of. And the other challenge is to make sure everything is safe and secure, so animals don't get out."

There are four giant pandas at the National Zoo. Three other US zoos in Atlanta, Memphis and San Diego also host giant pandas.

Pandas are clearly the stars of the week for Americans.

On Tuesday night, the Animal Planet channel premiered the Panda Republic, a two-hour documentary with an introduction by Michelle Obama. The US first lady and her two daughters visited the Chengdu panda base in March 2014.

The documentary tells the plight of giant pandas worldwide and draws attention to two Chinese giant panda centers dedicated to save the species.

Tai Shan, a giant panda born in the National Zoo in 1995, who was sent back to China in early 2010 for breeding purposes, also was featured in the film.

Kung Fu Panda 3, a 3D, computer-animated action comedy martial arts film jointly produced by American and Chinese companies, will hit theaters across the United States on Friday.

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