CHAPTER I 



The Living Bird 



Before we can speculate on the possible capabili- 

 ties of a bird, mental or physical, it is essential that 

 we acquaint ourselves with the general principles of 

 the avian constitution. It is useless, for instance, 

 to bestow on a bird human powers of thought if the 

 structure of its brain obviously precludes any such 

 possibility. Whether we wish to credit it with 

 powers of long-sustained flight or with such a simple 

 thing as the appreciation of color, we are not justi- 

 fied in so doing merely on the strength of personal 

 opinion. The least we can do, before committing 

 ourselves, is to study the elementary facts of the 

 anatomy and physiology of a bird and ascertain if 

 our assumptions are justified. If on these grounds 

 they are not, there is no choice but to modify our 

 hypothesis to suit the facts. We may therefore 

 profitably start our consideration of migrations by 

 making a brief survey of bird structure and function. 



Quite the most striking thing about a bird to the 

 comparative anatomist is the large number of fea- 

 tures that impress him as being essentially reptilian. 

 This is far removed from what we would naturally 



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