PLAN OF THE WORK 3 



It should be added that in the selection of material, other things 

 being equal, preference has been given to articles which have appeared 

 in magazines, and in the publications of scientific societies which are 

 comparatively inaccessible ; while those books which can be more 

 readily purchased have been used only when other sources of infor- 

 mation have failed. 



A list of the contributors, or co-authors of this volume is 

 given on a succeeding page, but it is desired here to specify the 

 nature of the material they have contributed, as well as to comment 

 in a more or less explanatory way, on the book's contents. 



Preliminary Chapters. The subjective matter herein contained 

 was prepared by the writer with the exception of the article on 

 'Migration,' which is by W. W. Cooke, and that on 'The Food of 

 Warblers,' which was written by E. H. Forbush. 



Descriptions of Plumages, etc. The description of plumages, 

 with remarks on genera and comments on species are by the writer. 

 They are based on the collection of the American Museum of Natural 

 History and the admirable series of carefully sexed Warblers in the 

 collection of Dr. J. Dwight, Jr., which is deposited in the museum, 

 but thanks are also due Robert Ridgway, Curator of Birds of the 

 United States National Museum, and Dr. C. Hart Merriam, Chief 

 of the Biological Survey, for permission to examine the birds under 

 their charge, as well as to William Brewster and Dr. L. B. Bishop 

 for an opportunity to study the Warblers contained in their private 

 collections. It is a pleasure to acknowledge here, also, the assistance 

 derived from the second volume of Ridgway's 'Birds of North and 

 Middle America' which includes the Warblers, and Dwight's 'The 

 Sequence of Plumages and Moults of the Passerine Birds of New York.' 



The measurement of 'Length' here given is taken from study 

 'skins', first, because a large series of measurements taken in the flesh, 

 of all the species treated, is not available; and, second, because it is 

 believed that the measurement of the length of a properly prepared 

 skin gives a more nearly correct idea of the size of the living bird, 

 than does the measurement of the recently killed, usually relaxed, 

 and more or less stretched specimen. 



Range. The paragraphs on distribution are, in the main, by 

 W. W. Cooke with additions by the author who is responsible for 

 the range given of the various subspecies of Warblers. 



Migration. The migration tables, assuredly one of the most 

 valuable features of the book, have been prepared entirely by W. W. 



