MAY 10 

 APRIL 30 



APRIL 20. 



Figure 22. — Migration of the western tanager. The birds that arrive 

 in eastern Alberta by May 20 do not travel northward along the 

 eastern base of the Rocky Mountains, as in that region the van has 

 then only reached northern Colorado. Instead the isochronal lines 

 indicate that they migrate north through California, Oregon, and 

 Washington, and then cross the mountains of British Columbia. 



coast of Asia to winter quarters in Japan, China, India, Australia, New 

 Zealand, and Oceania, including the Hawaiian Islands, the Marquesas 

 Islands, and the Low Archipelago. Golden plovers in migration 

 have been observed at sea on a line that apparently extends from these 

 islands to the Aleutians, and it therefore appears certain that at least 

 some of the Alaskan birds make a nonstop flight across a landless sea 

 from Alaska to Hawaii. While it would seem incredible that any birds 



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