XI'AN－The crested ibis, an endangered bird once thought to be extinct, is thriving thanks to decades of joint cooperation between China and Japan.

The "Oriental Gem", with its iconic red crest and long black beak, was believed to be extinct in China until seven wild birds were observed by Chinese ornithologist Liu Yinzeng and his research team in 1981 in Yangxian county, Shaanxi province.

"We felt both excited and pressured after the discovery," said Lu Baozhong, then head of the crested ibis protection team. "Team members safeguarded the birds 24 hours a day, spreading butter on trees and installing protective devices to deal with their natural enemies such as snakes."

One of the oldest bird species in the world, the crested ibis population has been increasing under joint protection efforts between China and Japan. China started captive breeding of crested ibises in 1991, producing more than 400 birds in Shaanxi and expanding their habitats. China now has over 3,000 crested ibises.

China donated five crested ibises to help rebuild the species in Japan in the 1990s, while Japan has been supporting the protection of the crested ibis habitat in China.

As an iconic bird deeply rooted in Japanese history and culture, the crested ibis decreased in number last century and Japanese-born ibises became extinct in 2003. The crested ibises in Japan today now number more than 500 and are all descendants of those from China.

"Crested ibises have become a bridge of friendship between China and Japan, and we hope there will be more of such exchanges in the future," said Yoshinori Kaneko, a vet at the Sado Japanese Crested Ibis Conservation Center.