On Turdus celaenops

Abstract

Turdus celaenops is a distinct species of thrush confined to the Seven Islands of Izu except Torishima. Its visit to the main island was recorded on five occasions. T. dissimilis of Burma and Yunnan, T. seebohmi of Borneo, T. obsourus, T. hortulorum and T. chrysolaus of the Palacarctic region are considered near relatives to T. celaenops. It is suggested that celaenops, chrysolaus, obscurus and dissimilis were derived from a same ancestral stock on the Asiatic continent and since the arrival of one strain to the Seven Islands, through selections and mutations, the present form, celaenops, was developed. Because the general resemblance in the plumage and the wing formula, celaenops is nearest related to chrysolaus.Yakushimensis, the only known subspecies in Yakushima, is not considered valid and; as these subspecies have been taken only in October, Yakushima birds were probably migrants from the Seven Islands. Parallel cases are phylloscopus occipitalis ijimae and Luscinia akahige tanensis, the Seven Islands breeding subspecies which are known to winter in Yakushima and further south to the Ryukyu Islands.