by the birds when on migration is unknown, though very few observa- 

 tions are available from the interior of northern British Columbia, 

 across which the route may lie. 



The southward route of those migratory land birds of the Pacific 

 coast that in winter leave the United States extends chiefly through the 

 interior of California to the mouth of the Colorado River and on to 

 winter quarters in western Mexico. 



The movements of the western tanager show a migration route 

 that is in some ways remarkable. The species breeds in the mountains 

 from the northern part of Baja California and western Texas north 

 to northeastern British Columbia and southwestern Mackenzie. Its 

 winter range is in two discontinuous areas — southern Baja California 

 and eastern Mexico south to Guatemala (fig. 21). On the spring 

 migration the birds enter the United States about April 20, appearing 

 first in western Texas and the southern parts of New Mexico and 

 Arizona (fig. 22). By April 30 the vanguard has advanced evenly to 

 an approximate east-and-west line across central New Mexico, Arizona, 

 and southern California. But by May 10 the easternmost birds have 

 advanced only to southern Colorado, while those in the far west have 

 reached northern Washington. Ten days later the northward ad- 

 vance of the species is shown as a great curve, extending northeast- 

 ward from Vancouver Island to central Albert and thence southeast- 

 ward to northern Colorado. Since these tanagers do not reach northern 

 Colorado until May 20, it is evident that those present in Alberta on 

 that date, instead of traveling northward through the Rocky Moun- 

 tains, which from the location of their summer and winter homes 

 would seem to be the natural route, reached there by the Pacific coast 

 route to southern British Columbia and thence across the mountains, 

 despite the fact that these are still partly covered with snow at that time. 



Pacific oceanic route 



The route of the Pacific golden plover is fully as interesting and 

 as remarkable as the elliptical course followed by its eastern cousin 

 (fig. 18). The breeding range of the eastern golden plover extends 

 through Arctic America west to the northern coast of Alaska where, 

 in the vicinity of Point Barrow, it meets the nesting grounds of the 

 Pacific form, which is really an Asiatic subspecies. It breeds chiefly 

 in the Arctic coast region of Siberia and merely overflows onto the 

 Alaskan coast, some of the birds probably migrating south along the 



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