348 



THE NATIONAL GEOGRAPHIC MAGAZINE 



MIGRATION ROUTK OF THE} BLACK-POLL WARBLERS THAT NE}ST IN ALASKA 



This bird winters in South America alongside the cliff swallow, but in summer seems to 

 try and get as far as possible from its winter neighbor.- Note how its northward route 

 diverges from the northward flight of the cliff swallow, shown on the map on the opposite 

 page. It travels at night, often flying several hundred miles in the darkness (see pages 

 349, 351, and 363). 



