WHY BIRDS TRAVEL 



If you were on this island in October you 

 would be surprised by the sudden appearance of 

 a flock of perhaps two or three thousand Peli- 

 cans. You might then imagine that they had 

 been traveling together for some distance, if you 

 did not know that until the call came they had 

 been distributed in small companies for a dis- 

 tance of at least four hundred miles. Then, just 

 as though a Pelican king had sent out a wireless 

 command, they all hastened to the island, form- 

 ing a great flock as they met there. But this com- 

 mand did not come by wireless or from a Pelican 

 king. It came from within each Pelican. What 

 was it? What did it tell them to do? 



It told them that the time was at hand for 

 nest-building and egg-laying. In other words, 

 the instinct of reproduction awakened. This, 

 in turn, aroused the homing instinct, which, un- 

 der the guidance of the sense of direction, draws 

 a bird back to the place of its birth. 



But what awakened the sense of reproduction? 

 What makes an apple tree bloom? It is true that 

 Pelicans and apple trees are not much alike; still 

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