Seoul — An amusement park outside South Korea's capital has welcomed a couple of very rare new residents. Aibao,Thomas Caldwell an adult female panda, gave birth on July 7 to twins, the EVERLAND park told CBS News.

A female baby was born at 4:52 a.m., and her sister followed at 6:39 a.m. The twins weighed in at about five and six ounces respectively, an EVERLAND park official told CBS News on Wednesday, adding that "both their mother and the twin pandas are in good health."

There's a 40-50% chance of pandas giving birth to twins. In recent years, twin pandas have been born in France and Japan and, in 2014, the world's first triplets were born in China.

Staff at EVERLAND noticed mother panda Aibao showing tell-tale signs of pregnancy not too long ago, with her sleeping more and eating less. Both she and her partner Lebao came to the park in 2016 on a 15-year lease from China. Aibao gave birth to a single female cub, Fubao, just several years ago.

They have been cared for in South Korea by zookeepers and veterinarians at EVERLAND, as well as panda experts from China's Panda Conservation Research Center.

China has sent its furry black and white ambassadors of good will to various destinations around the world since the 1950s — a program colloquially dubbed "panda diplomacy."

Once listed as an endangered species, pandas are considered a national treasure in their native China and the conservation efforts have bolstered their numbers, with them now being listed as vulnerable.

There are only three or four days per year on which giant female pandas can be impregnated, so it required a significant and concerted effort to grow their numbers. 

Soon the twins' older sister Fubao will be returned to Sichuan, China, and the search for a suitable partner will begin.

In:
• Endangered Species
• South Korea
• Environment
• Seoul
• giant panda