Page:The Migration of Birds - Thomas A Coward - 1912.pdf/103

Rh depart, in a single season, from ancient habits and carve out an entirely new migration route. Probably the origin of the route is as follows. The bird breeds on the northern shores of eastern Siberia from the Liakof Islands to Behring Strait, and on the Alaskan side south to the northern base of the Alaska peninsula. It winters on the mainland of south-eastern Asia, in eastern Australia, and throughout the Oceania Islands from Formosa and the Liu Kiu Islands on the north-West to the Low Archipelago in the south-east.

It is fairly certain that the original route would be roughly north and south, between Siberia, and southern Asia. In time the species spread eastward in winter, to Australia and to islands farther east, whilst the breeding area extended to Alaska. If these extensions took place before any cutting off of corners in the route, Alaska birds would travel 11,000 miles to reach the Low Archipelago, only 5000 miles in a direct air-route (No. 1). Probably shortening began early among the Pacific islands, from the northern islands to the Asiatic coast, and finally to Japan (No. 2). From Palmyra the flight to the nearest of the Marshall Islands is 2000 miles; thence a journey, provided with several possible rests, of 3000 miles would bring them to Japan. A thousand-mile drift through strong winds might cause the birds to reach Hawaii, whence they would