MADRID — Madrid’s panda family grew Monday with the birth of twin cubs, a boost to the popular species that is considered China’s national treasure.

The twins were born to their mother, Hua Zuiba, and father, Bing Xing, a pair of giant pandas on loan from China, the Madrid Zoo announced in a statement.

The births took place with a four-hour difference on Monday morning, the zoo said. Veterinarians were waiting to determine the pair’s sex, weight and vital signs. But the zoo statement said the birth had been “calmer” due to the mother’s experience.

Madrid’s adult pandas have had four other cubs earlier, including another pair of twins in 2010. They were all sent back to China after a few years in the Madrid Zoo.

In a video released by the zoo, Hua Zuiba can be seen vocalizing while moving into the labor position. A cub appears in just a few seconds, wiggling energetically before the mother takes the newborn with her mouth and licks it while holding it in her lap.

Panda cubs are born without hair, with a pink skin and are completely dependent from their mother for at least four months.

China’s Chengdu Research Base of Giant Panda Breeding sent two experts for the births in Madrid, the zoo said, and they will be assisting with the first weeks of breastfeeding.