著者

川路 則友 白石 哲

出版者

九州大学

雑誌

九州大學農學部學藝雜誌 (ISSN:03686264)

巻号頁・発行日

vol.34, no.3, pp.123-132, 1980-07

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We examined the avifauna in and around the Nagasaki Airport, and investigated the behavior and food habits of the Black-eared Kite, Milvus migrans, which roosted in Usu-jima Islet near the airport from June, 1977 to March, 1979. The results obtained are as follows: 1. Sixty-two bird species belonging to twenty-six families were observed in and around the airport. In the course of census, we found wintering of the American Golden Plover Pluvialis dominica from 1977 to 1978, and the Chinese Great-grey Shrike Lanius sphenocercus on January 10, 1978 which had been rarely observed in Kyushu, Japan. In the airport the dominant species were always the Skylark , Alauda arvensis, and the Tree Sparrow, Passer montanus. 2. The Black-eared Kites left the roost in Usu-jima early in the morning, and flew to the feeding area, but some kites remained on and around Usu-jima all day long. The maximum number of kites is highest between September and November, and they decreased markedly in December; they increased again from January to February, but only a few individuals were observed between March and July. These changes in abundance of kites probably reflect their migratory movements. 3. Between September and October many kites moved in a wide area, but less so in other months. Especially in December, all kites lived within a very restricted area. Accordingly, the extension and reduction of the daily movement seem to relate to the feeding area, which changes with fluctuations in kite's abundance. We found another roost in Osaki Peninsula, north to the Nagasaki Airport, and there seemed to be other two roosts. The kites roosting here seemed not to move so far. Since there is abundant food for the kites along the coast, it seems enough for their existence to feed within a narrow area. 4. Fishes were most abundant as food items of the Black-eared Kites and a kind of gobies, Chaeturichthys hexanema, occupied the highest percentage of them, being followed by insects. Especially in October, a number of kites gathered at the airport in order to feed on locusts which inhabited the grassland, so that the ratio of kites with stomachs including insects temporarily increased. Other foods detected were the kite (probably fed after death), skylark and a kind of pill-bugs, Armadillidium vulgare.1.1977年6月から'79年3月まで,長崎空港周辺の鳥相および臼島を塒とするトビの行動と食性について調べた.2.長崎空港周辺で確認された鳥種は26科62種に達したが,特筆すべきこととしてムナグロの越冬(1977年から'78年にかけての冬)とオオカラモズの確認(1978年1月10日)を挙げた.空港内ではヒバリとスズメが常に優占種であつた.3,トビは朝早く臼島の塒から飛び立ちえさ場へ向かうが,同島やその周辺で終日生活する個体も多く確認された.月別に見た1日のうちのトビの最大個体数は9月~11月に多く,12月になると激減し,1,2月には再び増加し,3月以降7月まで少なかつた.その原因としては渡りが考えられた.4.個体数の最も多い9,10月には直線距離にして最大10km程度の飛翔を行なつて広範囲に行動する個体が増加するが,それ以外の月にはそれほど遠くへ出て行く個体は見られず,特に12月にはすべての個体は1~2kmの範囲内で生活していることが知られた.従つて,これら行動範囲の拡張と縮小は個体数の増減に対応したえさ場の確保と関係があると考えられた.車によるライン・センサスの結果,臼島のほかに確実に1ヵ所,また明示はできないが更に2ヵ所の塒があると推察されたが,それらの塒の個体もさほど遠距離まで行動しないと思われた.恐らく,海岸沿いには常に餌が豊富に存在し,ある程度までの個体数は塒の近距離内で許容されるためと考えられた.5.トビの食物としては魚類が最も多く,その中でもアカハゼが主食となつていることが知られた.次いで昆虫類が多く,特に10月には空港の草原に生息するバッタ類を採食しに飛来するトビが増加し,昆虫を採食している個体の割合が一時的に増大した.そのほかの食物としては鳥類のトビとヒバリ,甲殻類のダンゴムシが確認された.