<国立科博専報>トカラ列島の繁殖鳥類とその起源

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The Tokara Islands, consisting of some 12 larger and smaller Cenozoic volcano islands, are situated between Yakushima and Amami Ohshima, off Kyushu, in southwest Japan. It is noteworthy that the Watase Line, which defines a boundary between the Palearctic and the Indomalayan regions, passes through the islands. Despite the zoogeographically interesting position of the islands, their avifauna hand received little attention until very recently. I made two trips to the islands, in June-July and August 1989,and collected representative bird specimens there. This paper gives distributional records and taxonomic notes on 26 breeding bird species (one is an introduced species) on the islands. Of 25 native breeding birds discussed in this paper 10 have origin on the Amami Islands and six on Japan mainland, Yakushima, or the Izu Islands. The breeding avifauna is no doubt a mixture of immigrants from all surrounding areas, although the immigrants from Amami Ohshima predominate (40%). Most interesting cases are the occurrences of the Izu Islands Thrush Turdus celaenops and of the Ijima's Willow Warbler Phyllscopus ijimae, both showing discontinuous breeding distribution in the Izu and the Tokara islands (T.celaenops also occurs on Yakushima). They are probably direct immigrants from the Izu Islands, contra to the relic hypothesis advocated by YAMASHINA (1942) and more recently by KAWAJI et al.(1989).
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