野生トキのひな 人との共生と日中協力が大切

The Yomiuri Shimbun
Cooperation from residents, China key to returning crested ibises to wild
野生トキのひな　人との共生と日中協力が大切

A chick has been born to a pair of wild toki Japanese crested ibises — a species designated as a special natural monument — on Sado Island, Niigata Prefecture. It is the first such delightful news in 40 years. We hope the chick will grow safely.
　新潟県の佐渡島で、特別天然記念物トキの野生のつがいから、ひなが誕生した。４０年ぶりの朗報である。ぜひとも無事に育ってほしい。

On Sado Island, artificially raised crested ibises have been released into the wild since 2008. The number of crested ibises that have bred in nature has also increased. The chick hatched this time was born to parents who were born and grew up in nature. It is in the grandchild generation of crested ibises released into the wild.
　佐渡島では、人工飼育したトキの放鳥が２００８年から続く。自然の中での繁殖も増えた。今回のひなは、自然界で生まれ育った親鳥の間の子供だ。放鳥されたトキの孫の世代にあたる。

The birth is a major milestone in the return of crested ibises to the wild.
　トキの野生復帰に向けた大きな節目と言えよう。

It has been confirmed that there are currently five pairs of wild crested ibises. We probably can expect more crested ibis chicks to be born in the future as well.
　現在、５組の野生トキのペアが確認されている。これからも、ひなの誕生が期待できそうだ。

The scientific name for the Japanese crested ibis is Nipponia nippon. One of its characteristics is its rose-pink — called toki color — feathers. The species used to live in a wide area of East Asia and was a familiar wild bird in Japan, too.
　トキは「ニッポニア・ニッポン」の学名を持つ。朱鷺とき色と呼ばれる淡紅色の羽が特徴だ。かつては東アジアに広く分布し、国内でも身近な野鳥だった。

However, the number of crested ibises sharply dropped due to overhunting for their feathers in the Meiji era (1868-1912) and afterward as well as the deterioration of their habitat. Japanese-born crested ibises that remained on Sado Island went extinct when the last bird died in 2003.
　しかし、羽毛を目的とした明治以降の乱獲や、生息環境の悪化で激減した。佐渡島に残った日本生まれのトキは、０３年に最後の１羽が死んで絶滅した。

Since 1999, the Environment Ministry has been artificially breeding the species with crested ibises donated or loaned from China. The ministry also trained them on how to catch prey. About ¥150 million is spent annually for a project to return crested ibises to the wild.
　環境省は１９９９年以降、中国からトキの寄贈や貸与を受けて、人工繁殖に取り組んできた。餌の採り方などの訓練も施した。トキの野生復帰事業には、年約１億５０００万円が投じられている。

Extinct species’ revival hard

This tells how difficult it is to revive a species that once disappeared.
　姿を消した生物の復活が、いかに難しいかを物語る。

Cooperation from local residents is essential for returning crested ibises to the wild. The amount of agricultural chemicals used in rice paddies was reduced so that loaches and earthworms — crested ibises’ prey — can grow there, and the paddies are filled with water even in winter.
　野生復帰には、住民の協力が欠かせない。トキのえさとなるドジョウやミミズが育つよう、水田での農薬の使用量を減らした。冬にも田に水を張っている。

Thanks to the efforts to have crested ibises coexist with humans, about 150 crested ibises now inhabit the island.
　島内に約１５０羽のトキが生息するようになったのは、人と共生するための取り組みの成果だ。

The ministry plans to release more than 30 crested ibises into the wild every year, with the aim of having 220 birds settled in nature in 2020.
　環境省は、今後も年３０羽以上を放鳥し、２０年には２２０羽が自然界に定着することを目指す。

There are many challenges in breeding crested ibises in nature. The first “completely wild” crested ibis chick whose birth was confirmed this time was believed to have died soon after birth. The cause of the death is unknown, but the birds have natural enemies such as crows.
　自然界での繁殖には試練が多い。今回、誕生が確認された「純野生」の１羽目のひなは、間もなく死んだとみられる。原因は不明だ。カラスなどの天敵もいる。

The ideal structure is for crested ibises born in the wild to increase their numbers on their own in the future by overcoming these difficulties.
　こうした困難を乗り越え、将来的には、野生で生まれたトキが自力で個体数を増やしていくのが、理想の姿だろう。

To this end, it is also important to secure genetic diversity among crested ibises.
　その実現には、トキの遺伝的多様性を確保することも大切だ。

Crested ibises currently living in Japan have five crested ibises from China as ancestors, and there are many pairs that are cousins. Their ability to resist diseases and their reproductive power could diminish if those in the same consanguineous group repeatedly mate with each other. It is important to have crested ibises continually provided by China.
　現在のトキは、いずれも中国からの５羽が先祖で、いとこ同士のペアが多い。血縁同士で交配が進むと、病気への抵抗力や繁殖力が低下する恐れがある。中国から継続的にトキの提供を受けることが重要になる。

China is also making efforts to return crested ibises to the wild. We hope for continued mutual cooperation through crested ibises such as providing China with techniques that Japan has developed to raise the birds.
　中国でもトキの野生復活に取り組んでいる。日本が培ってきた飼育技術を提供するなど、トキを通じた相互協力を続けたい。

(From The Yomiuri Shimbun, May 4, 2016)