山階鳥類学雑誌
Online ISSN : 1882-0999
Print ISSN : 1348-5032
ISSN-L : 1348-5032
報告
2002~2016年に茨城県稲敷市江戸崎入干拓地で越冬したオオヒシクイの渡り日と個体数
武藤 隆一綿引 清雄小玉 和夫
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2017 年 48 巻 2 号 p. 87-93

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A decrease in wintering sites in other countries caused by global climate change and other factors is one of several theories proposed to explain the increase in the number of large waterbirds wintering in Japan. As such, any increase in the number of geese wintering in Japan would not necessarily provide an optimistic view of recovery of population size, making it important to pay continuously monitor fluctuations in the number of wintering geese. Since 2002, we have counted the wintering Bean Goose Anser fabalis middendorffii in Edosaki-Iri Reclaimed Land, the only wintering site of this species in Kanto District, Japan. During the 14-year study period, the first individual arrived at the study site from mid-October to mid-November, and thereafter the number of individuals gradually reached a plateau within 13–46 days. Geese remained at the wintering site an average of 126.2±14.6 SD days (n=14), and the average maximum number of geese present during the plateau phase was 79.5±26.4 SD (n=14). Over the study period, geese usually began departing the wintering site in late February, and in most years geese departed the wintering site over a much shorter period that in which they arrived. In all years, all birds had left by late March. Arrival and departure dates remained relatively constant throughout the 14-year study, as did the wintering period. However, the maximum number of wintering individuals increased as the study progressed.

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© 2017 公益財団法人 山階鳥類研究所
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