PART II, 



INTRODUCTION. 



ORNITHOLOGISTS of the present day are much indebted to 

 the earnest and enthusiastic men who studied the habits 

 of our birds in years past ; but truthful and careful though 

 they may have been, being but men, they were fallible. As 

 this is an age of advancement, it behooves us of the present 

 day, while we are in a measure guided by these teachings, 

 not to be biased by their conclusions, that we may detect 

 the errors which they unconsciously committed. 



If, while endeavoring to correct some deeply seated error 

 of the past, we disagree with our brother ornithologists, 

 let us, with the spirit of the true naturalist, who would 

 advance the study of Natural History, bring infallible proofs 

 of its being an error, thereby convincing without offending. 



If in the following pages I unwittingly make mistakes, 

 I am ready to be convinced by sufficient proof. 



In separating birds into species, too much dependence 

 has been placed upon exceedingly variable characters as 

 valid specific distinctions. For instance, the bill, although 

 in the main retaining its shape, is sometimes subject to 

 wide differences ; this is well illustrated in the Terns, 

 where they are extremely changeable in the length and 

 curve of the culmen ; they also vary in coloration ; yet 

 in determining species, these points are now, and always 

 have been, considered of value. 



The comparative length of the quills is another very 



