HOW THE BIRDS KNOW 331 



wiping out that beautiful theory that the old birds 

 make their migration by landmarks they recognize, 

 and teach the young the routes. He amply sus- 

 tains the contention that birds are frequently 

 deceived. He states the proper time for migration 

 and then gives figures to prove that thousands lose 

 their lives in a night through flying into a storm 

 and breasting adverse conditions. He mentions 

 puffins among the birds which frequently make 

 mistakes as to when it is safe for them to migrate. 

 Three points of intense interest in migration are 

 how birds find their way on nights of fog and dark- 

 ness, when the theory concerning their following 

 river valleys or recognizing bridges and light-houses 

 is utterly untenable; the height to which they fly; 

 and the speed. Herr Gatke's records show that 

 the greater part of successful migration is carried 

 on so high that while he heard the chatter of passing 

 throngs and saw the shadows between him and the 

 moon, he saw nothing of the birds except the weak- 

 lings and strays, which often dropped to his level 

 through exhaustion, and paused to feed and rest. 

 In support of the theory of high flight, Mr. G. 

 Tennant states in his book, "Stray Feathers," 

 that while studying the sun through a telescope, 

 he identified as kites flocks of birds passing through 

 his vision. This brings the nearest bird a mile 

 above the earth, and the farthest several miles 

 higher. These birds were not in migration; they 

 were soaring. I mention the fact merely to prove 



