WHY BIRDS TRAVEL 



Pelicans gradually returned to the country from 

 which they had been driven. Now, as we have 

 seen, they have actually gone as far back as 

 Great Slave Lake. But every winter when the 

 water freezes they go South, only to return as 

 soon as the ice thaws in the spring. So through 

 many centuries they slowly formed the habit of 

 making a journey which gradually grew longer 

 and longer. 



So then we may think of the marvelous travels 

 of birds as due, first of all, to those changes in 

 climate which turned a warm Arctic to a cold 

 Arctic. As the ice gradually receded, the hom- 

 ing instinct led the feathered exiles back to the 

 land they had been forced to desert. The 

 "blooming" or reproductive instinct tells them 

 when to go, and the sense of direction guides 

 them on their way. 



SUGGESTIONS FOR STUDY 



Have you ever seen Wild Geese migrating? De- 

 scribe their flock formation. Can you suggest any 

 reason for the birds' journey? Do our summer 

 birds leave their winter quarters in the tropics be- 

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