The over-sea crossings of land birds in the western Pacific

Abstract

Japan lies apart from the continent and many migration routes to and vir this archipelago are innevitably sea-crossing, for example, Japan Sea and China Sea crossings, 425-480 miles. Many stray autumn migrants of land birds reach the Bonin and Volcano Is., possibly aided by oceanic wind drift after crossing 500-600 miles and more may perish on the ocean. They seem to survive the winter on the islands but the summer records are extremely few and spring migration from the south is not evident. This is supported by the fact that actually no Passerines reach Marianas, N. Micronesia, though some palaearctic ducks further reach W. Carolines and even Marshall Is. There are, on the other hand, some northern migrant species which reach Palau Is., SW. Micronesia, from the Philippines crossing 580 miles of the sea, perhaps also aided by winds. Except the waders, only a few American ducks could reach the Marshall Is., E. Micronesia, after flying vast Pacific Ocean.