I40 WITH THE U. S. NATURALISTS 



birds which would survive best would be those who 

 were the most adventurous, daring the borders of 

 the ice in summer and only returning to the 

 struggle-riven section of the equatorial zones dur- 

 ing winter. The migratory habit thus became 

 settled in the instinct of birds and they continue 

 to migrate now though the original stimulus is re- 

 moved and the need is nowhere so great. 



"From the earliest times, Man has observed the 

 regularity of the migration of birds. 'The stork 

 in the heavens knoweth her appointed time,' says 

 the Old Book, 'and the turtle (dove) and the crane 

 and the swallow observe the time of their com- 

 ing.' " 



"Do yo' reckon the old birds tell the j'^oung 

 when to start!" asked Bull. 



"Perhaps, in some cases they do," the expert 

 agreed, "and undoubtedly among some of the mi- 

 grating species there are signs of teaching, such 

 as the following of a leader and obedience to pre- 

 concerted calls, but, at the same time, it is sure 

 that education cannot exjjlain migration, for the 

 young of many birds start in advance of their 

 parents. The Cowbirds — who dodge parental 

 responsibilities, like the European Cuckoo — leave 

 before the young. Quite often they leave in the 



