FACTORS IN ANIMAL LIFE 



varying degrees of excellence — that is, first nests in 

 the spring. The second nest of any species is likely 

 to be a more hurried and incomplete affair. Some 

 species are at all times poor nest-builders, as the 

 cuckoos and the pigeons. Other birds are good nest- 

 builders, as the orioles, the thrushes, the finches, 

 the warblers, the hummingbirds, and one never finds 

 an inferior specimen of the nests of any of these 

 birds. There is probably no more improvement in 

 this respect among birds than there is among insects. 



I have no proof that wild birds improve in singing. 

 One does not hear a vireo, or a finch, or a thrush, or 

 a warbler that is noticeably inferior as a songster 

 to its fellows; their songs are all alike, except in the 

 few rare cases when one hears a master songster 

 among its kind; but whether this mastery is natural 

 or acquired, who shall tell ? 



What birds learn about migration, if anything, 

 I do not see that we have any means of finding out. 



It has been observed of birds reared under artificial 

 conditions that the young males practice a long time 

 before they sing well. That this is true of wild birds, 

 there is no proof. What birds and animals learn by 

 experience is greater cunning. Does not even an old 

 trout know more about hooks than a young one? 

 Birds of any kind that are much hunted become 

 wilder, even though they have not had the experience 

 of being shot. Ask any duck or grouse or quail 

 hunter if this is not so. Our ruffed grouse learns to 

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