HISTORICAL REVIEW 



A review of the progress which has been made in the study of North 

 American birds during the eighteen years since the first edition of the 

 "Handbook" was published must impress one with the fact that it is 

 our knowledge of living rather than of dead birds which has increased. 



A more exact discrimination, larger and better collections, and 

 gradually changed standards as to the degree of differentiation which 

 deserves recognition by name, have added many forms to our "Check- 

 List," and rendered more definite our knowledge of the relationships 

 of others. Particularly is this true of the birds of the Pacific coast 

 region. This systematic work has appeared in various special papers 

 and monographs, the most thorough of which, not only for the period 

 under consideration, but for any preceding period in the history of 

 North American ornithology, is Ridgway's "Birds of North and Middle 

 America," of which five volumes have thus far been issued. 



Thanks to the American Ornithologists' Union, our nomenclature 

 has been revised with the utmost care and, while the numerous result- 

 ing changes in names may be annoying to present-day students, those 

 who follow us will enjoy, in greater measure, that stability which is 

 the ideal of the biologist. The third (1910) edition of the Union's 

 "Check-List" contains this modern nomenclature; but it is worthy of 

 note that the classification employed in this work is the same as that 

 used in the first (1886) edition of the "Check-List." So little advance 

 has been made in this branch of ornithology that no system of classi- 

 fication proposed since 1886 was considered sufficiently satisfactory 

 to warrant adoption by the Committee of the Union having in charge 

 the preparation of the 1910 edition. 



The studies of Dwight and others have made far more definite 

 our knowledge of the molt of birds, the times and manner of feather- 

 loss and renewal having been determined for many species, with an 

 exactness made possible only by the collecting of specimens for this 

 special purpose. At the same time, Beebe, by experiments on captive 

 birds, has attacked the problem of the causes of molt, while Strong's 

 histological work on the feather has increased our understanding of 

 its growth and development. 



In laboratory experiment on living birds, Beebe has shown certain 

 effects of humidity upon the colors of feathers; Davenport has used 

 Canaries and domestic fowls in working on the laws of heredity; Porter 

 and others have conducted psychological investigations upon certain 

 species; and Watson has pursued similar studies upon the Noddy and 

 the Sooty Tern in nature. The highly original researches of Thayer 



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