Smithsonian National Zoo in Washington DC received a happy surprise on Saturday when an endangered giant panda successfully gave birth to two cubs.

Although the panda, named Mei Xiang, had been artificially inseminated on two previous occasions and had displayed some signs of pregnancy, such as sleeping more and building a nest, keepers at the zoo only discovered she was pregnant at the last minute –during an ultrasound scan last week.

Our panda team believes Mei Xiang is in labor! We’re hoping for a healthy cub. #PandaStory http://t.co/S7WWws1JTy pic.twitter.com/Hs7sp6N5rW

— National Zoo (@NationalZoo) August 22, 2015

Keepers were delighted at the news, but Mei continued to surprise and delight her carers by "popping out" a second cub a few hours after the first.

VIDEO: Giant panda Mei Xiang gives birth to a cub at 5:35 p.m. Aug. 22, 2015 http://t.co/FQDg4GtidN #WeSaveSpecies #PandaStory

— National Zoo (@NationalZoo) August 22, 2015

"I looked over at the camera and out popped a cub," exclaimed the zoo's chief veterinarian, Don Neiffer.

"So we immediately jumped into, 'Okay, what do we do now.' We watched to see how Mei Xiang would handle two. We gave her a little bit of time to actually see if she would pick both cubs up, but she was really struggling.

"She was trying, but she wasn't able to pick up both of the cubs. So we did go in and at the right moment and pick up one of the cubs when Mei Xiang was not really close to it."

First born giant panda cub vet exam. This cub is vocalizing well & appears strong. #PandaStory #WeSaveSpecies pic.twitter.com/Vc89FJp517

— National Zoo (@NationalZoo) August 23, 2015

The tiny, hairless cubs are totally reliant on their mother for food, warmth and protection. However, due to concerns that Mei wouldn’t be able to successfully nurture both cubs out to independence one has been removed and placed in an incubator. The team hopes to regularly switch the cubs in order to allow Mei quality time with both babies.

 

^{Weighing just under five ounces, both cubs appear to be doing well. Photograph by Pamela Baker-Masson, Smithsonian's National Zoo}

The cubs are yet to be sexed and probably won't be for at least 3 or 4 weeks, the Museum has stated, but both cubs appear to be doing well so far and are being monitored closely by the team of experts.

According to the WWF, giant pandas are one of the rarest and most endangered bears in the world. Previously inhabiting China, northern Vietnam and northern Burma, the bears can now only be found in the wild in six isolated mountain ranges in south-central China.

Huge numbers of the giant bears were lost between the early 1970s and late 1990s due to poaching and habitat loss. Three quarters of all wild pandas now live in nature reserves in an attempt to preserve current numbers and provide a safe environment for pandas to breed and raise young. 

Although a high percentage of panda births in captivity involve twins, due to the temperamental nature of panda reproduction (females ovulate only once a year), for just three to four days in spring), the number of successful pregnancies and cubs reaching maturity is low, so the news of a healthy set of panda cubs has spiked a fresh wave of confidence in boosting panda numbers in captivity.

[H/T: AFP]