A STUDY OF ACQUIRED HABITS 61 



There are two points to be considered : the 

 habit long remained unknown ; after it was dis- 

 covered, it was long in being reaffirmed. It 

 seems that, if it were a general habit, more 

 would be known about it. Now if it is not a 

 universal habit, it must be one of two alterna- 

 tives, either a custom falling into disuse, or a 

 new one just being acquired. That a habit so 

 remarkable and so advantageous should be dis- 

 carded after being universal is scarcely possible ; 

 that a habit so noticeable, if it were general, 

 should remain unknown is improbable ; that a 

 habit which made life in winter both secure and 

 easy should, if introduced by a few enterprising 

 birds, become a universal custom, is not without 

 a parallel. The probabilities point to the custom 

 of hoarding food as a recently acquired habit. 



Acquired habits are not rare among birds. 

 The chimney swift has learned to nest in chim- 

 neys since the Pilgrims landed ; for there were 

 no chimneys before that time. There is the evi- 

 dence of old writers to show that they acquired 

 the habit within fifty years of the time of the 

 first permanent settlements in New England. 

 The eaves swallow learned to transfer its nest 

 from the side of a cliff to the side of a barn 

 in less time. Most birds will change their food 

 as soon as a new dainty is procurable, and they 



