THE ALLIES OF THE PIGEON 



395 



of the Statue of Liberty in New York Harbor after a dark 

 night in the migration period. Attracted by the bright 

 light the birds had dashed against the glass in their 

 swift flight. Birds are exposed to other dangers on their 



Fig. 209. Map showing migration of the bobolink 

 Courtesy of the United States Department of Agriculture 



migration flight. They are fed upon by other animals, or are 

 blown out to sea, where they fall exhausted into the water. 

 It is not thoroughly understood how birds find their way 

 over such great stretches of territory. The "fly lines" of 

 some swallows are ten thousand miles long. The golden 



