Notes on the zoogeographical distribution of the Snow Bunting, Plectrophenax nivalis pallidior Salmonsen in Japan

Abstract

The snow bunting has hitherto been considered in this country as a stray bird or a rare winter visitor to Hokkaido. In 1961 and 1963 the writer observed, however, relatively large flocks (consisting of 30-200 birds) of this species three times in and around Sapporo County, Hokkaido. One individual of them was caught in Ishikari County near Sapporo, its stomach contents being analyzed as given in Table 1. The measurements of the specimens accessible to the writer, including 17 specimens of the Natural History Museum, Hokkaido University, are shown in Table 2. All the records known to the writer, including unpublished personal communications, of capture and observation of this species are summarized in Table 3. These twenty-seven records tell us that it might be found in Japan from September 15 to March 22. Six of these records are from Honshu and four of them were observed at Hakui, Ishikawa Prefecture, being reported to concern probably the same 2 individuals observed four times intermittently in the same area. One snow bunting was caught at the mouth of river Kurobe, Toyama Prefecture. These five cases suggest that the snow bunting might be considered as stray birds in these localities situated in lat. about 37°N. The remaining one record, on the other hand, is of 24 birds captured at Shonai (lat. about 39°N), Yamagata Prefecture, and suggest the possibility of its being a winter bird rarely migrating to the south in North-eastern Honshu. Finally in Hokkaido (lat. about 41.5-45.5°N), where relatively few persons are known to observe birds on open fields in wintertime, the snow bunting may possibly be a common winter bird, rather than to be stray birds or rare winter visitors.