All four eggs laid by Mei Mei, a crested ibis donated to Japan by China in October, have probably been fertilized, the Sado Crested Ibis Conservation Center on Sadogashima Island, Niigata Prefecture, said Tuesday.
The four eggs are the first produced by Mei Mei and her mate Yu Yu, who began mating on March 20.
The eggs were laid between March 26 and April 3, when they were carefully removed from the nest and placed in an incubator. The news that they have probably all been fertilized will be welcomed by conservationists in both China and Japan.
Under an agreement between the two countries, the couple's first chick will be returned to China and the second will remain in Japan.
Mei Mei was born April 10, 1999, at a crested ibis preservation center in China's Shaanxi Province. Yu Yu was born in Japan in May that year to Yang Yang and You You, who were a gift from Chinese President Jiang Zemin to the Emperor during his 1998 visit to Japan.
Yu Yu was the first ibis to be born in an incubator in Japan.
The crested ibis is an endangered species. Although its scientific name is Nipponia Nippon, the birds are virtually extinct in Japan. Only one ibis born in the wild in Japan remains -- a female named Kin -- who is thought to be more than 30 years old and is kept at the Sado center.