TOKYO (Kyodo) -- The Japanese government said Thursday it will transfer 16 crested ibises born northwest of Tokyo to China, the birthplace of their parent birds, on Oct. 31.

A handover ceremony will be held Tuesday, with Chinese officials receiving the birds at a conservation center on Sado Island in Niigata Prefecture, marking the first such return of the internationally protected birds in eight years.

Japanese-born ibises became extinct in 2003, but Japan has been artificially breeding ibises using birds donated by China since 1999.

According to memoranda of understanding between the two countries, half of the offspring born through this method must be sent to China, although the last transfer occurred in 2016, with none taking place in recent years due to the COVID-19 pandemic.

According to the Environment Ministry, the 16 crested ibises -- seven males and nine females -- are being quarantined for bird flu and other diseases ahead of the transfer to Beijing Zoo.

As of the end of 2023, 532 crested ibises were estimated to live in the wild in Japan, while around 175 are kept in facilities in Tokyo, Niigata, Ishikawa and Shimane prefectures as the end of July, the ministry said.

Between the first handover in March 2002 and the last one in 2016, a total of 47 birds were sent to China across seven exchanges.