The Bird Book 



would be useless and accordingly it is altered by 

 a contrivance as simple as it is effective. It would 

 be easy to multiply instances, did space permit, 

 but it is better to leave the discovery of such 

 contrivances to the reader, for one of the chief 

 interests in the study of bird-life is to find out the 

 special mission of each species and observe how 

 wonderfully each is armed for the fulfilment of its 

 task. 



We must now turn our attention to flight, 

 which, though not peculiar to birds, forms, never- 

 theless, their chief characteristic. Owing to the 

 nature of their food, birds have to search greater 

 areas than mammals and consequently flight be- 

 comes a necessity. Moreover, their food, especially 

 insect food, is not always to be found in the same 

 country all the year round, a fact which brings 

 us at once face to face with the question of 

 migration, one of the most fascinating and difficult 

 of all problems connected with bird-life. Gilbert 

 White could not quite rid himself of the notion 

 that Swallows hibernated at the bottom of ponds, 

 but now the countries in which most of our sum- 

 mer visitors spend the winter, and some of the main 

 routes by which they travel, are well known, and 

 we are learning something of the immense speed 

 they attain and the height at which they fly. 

 From Heligoland to Egypt in a night sounds very 

 romantic, yet we have it on good authority that 

 some birds accomplish this feat, and that some of 



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