著者

石沢 慈鳥

出版者

The Ornithological Society of Japan

雑誌

鳥 (ISSN:00409480)

巻号頁・発行日

vol.16, no.78, pp.409-413, 1961-12-15 (Released:2009-02-26)

被引用文献数

3 1

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Judging by the personal reports received by the author from lighthouse keepers in various parts of Japan, the following may be suggested as possible behaviour of night migrants, particularly the Passrines. 1) The passage of night migrants is noticed offshore rather than ashore where there are islands and capes to avoid, and they fly low close to the seasurface. 2) As generally said, they migrate in clear nights, but when the sky suddenly became overcast or rainy, they may be lost and if a lighthouse were close enough its dim light may attract them. In such cases, some of them die struck at the lighthouse and others spend the night nearby to start again in the next favourable evening. In clear night this never happens. 3) The second case of migrant destruction at lighthouses occurs when the weather was good during the day and became cloudy or rainy towards evening. On such a day, migrants gathering around lihthouse at a cape where there are usually good cover for rest, become restless to start for night flight, but the sudden overcast condition urges them only to fly around the light and some or numbers of them will strike at it. 4) Stronger the light the more migrants are attracted from greater distances and the lighthouse at more unstable weather condition is responsible for more migrant victims. 5) In recent years, however, the birds struck at lighthouses has become extrmely fewer, owing possibly to: a) the genereal decrease of bird numbers and b) increase of coastal village lights and lights of fishing boats on the coastal seasurface.