Right: Giant panda twins born in the United States are named Ya Lun (left) and Xi Lun at their 100-day celebration on Monday at Zoo Atlanta. Their mother Lun Lun, from top left, checks the twins on Sept 3 after their birth. By Sept 9, they have started to grow hair, and by Oct 10 they have begun to look more like their current selves.Provided By Zoo Atlanta

The only giant panda twins in the United States were named Ya Lun and Xi Lun at the cubs' 100-day naming celebration on Monday at Zoo Atlanta.

Ya means "elegant", and Xi means "happy". Lun honors Lun Lun, mother of the twins. Together, the names mean "Lun Lun's elegant and happy daughters".

The winning names are from among seven sets supplied by conservation partners in Chengdu, in Sichuan province. The names Ya Lun and Xi Lun received over 11,000 of the more than 23,400 votes cast by panda fans worldwide.

"As we wish Ya Lun and Xi Lun well today, we celebrate the future of their species together," said Raymond King, president and CEO of Zoo Atlanta.

The twins, who are learning to walk, were not present. They should make their debut in late December or January.

The 100-day celebration, used for all seven Atlanta-born giant pandas, is an ancient Chinese tradition based on having survived infancy. Born on Sept 3, the pair are the second set of twins for Lun Lun and the sixth and seventh offspring of Lun Lun and Yang Yang.

All giant pandas at the four US zoos housing them are owned by China, said Rachel Davis, director of communications at Zoo Atlanta.

"As part of our loan agreement with China, all of the offspring of our adult pair, Lun Lun and Yang Yang, do eventually travel to China when they are around 3 years old," Davis said. She said the new twin cubs also will be sent to China in a few years.

The zoo has contributed more than $10 million to the survival of wild giant pandas. Thanks to conservation efforts in China and at institutions around the world, the International Union for the Conservation of Nature downgraded the giant panda's status from endangered to vulnerable in September.

However, the species remains heavily reliant on conservation programs. Fewer than 1,900 giant pandas are estimated to remain in the wild in Sichuan, Shaanxi and Gansu provinces.

Xie Fei, cultural consul from the Chinese Consulate General in Houston, attended the ceremony and praised Zoo Atlanta for its efforts.

"The zoo has over the years provided valuable support and expertise for the conservation of the giant panda and its habitats in China, which is highly appreciated by the Chinese government and people. The giant panda program exemplifies the China-US cooperation."

mayzhou@chinadailyusa.com