Chestnut-sided Warbler— A Study 



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lie warned to kfcp from a C'hcstmit-sidfd Warbler's nest after the younj^ 

 birds are a few days old, for the\- seem to possess an unusual nervous irritabilitv 

 and gain the fear in>tin(t at an unu>ually early period. TheN' bi'( ome frantic 

 at any disturbance, c'\-en when the feathers extend from tlu'ir tubes so little that 

 the birds seem covered with minute camel's hair bru>he>, at a time when most 

 nestlings have an undisturbed, dignified manner because knowing nothing of 

 fear. They leap from the nest and even if caught and returned are likely to refuse 

 to stay. Perhaps all Chestnut-sided Warblers do not gain the fear instinct as 

 early as did those of three broods observed (instead of onlv one to three days 

 before flight). But if they do, it would seem that here natural selection has a 

 handle by which to keep the ranks of this species well reduced. 



R<1SE liREASTED GROSBEAK AND NEST 

 Photograptied by F. E. Howe, Sterling, 111. 



