x HISTORICAL REVIEW 



have greatly stimulated interest in the study of the colors of birds in 

 relation to their environment. 



Dealing still with the more technical branches of ornithology, the 

 investigations of Fisher, Beal, and other members of the Biological 

 Survey of the United States Department of Agriculture, of Forbush 

 in Massachusetts, and of other state ornithologists, have supplied by 

 far the larger part of our exact knowledge of the food-habits of our 

 birds and determined for the first time the economic status of many 

 species. This work constitutes one of the most pronounced and impor- 

 tant phases of research during the period under consideration. While 

 based, primarily, on field work in observing as well as in collecting, 

 special training in laboratory methods is required to make the analyses 

 of stomach contents, from which, in the main, the nature of a bird's 

 food is ascertained. 



Field, as well as laboratory work, has also been required to produce 

 the faunal papers and books which, in volume, form the greatest addi- 

 tion to the ornithological literature of the past decade and a half. From 

 the pioneer explorations of Merriam, Fisher, Nelson, Bailey, Preble, 

 Osgood, and other members of the Biological Survey, in new or but 

 little-known regions, to the almost final reports of Brewster and others 

 on .the bird-life of localities which have been studied for years by many 

 observers, these publications have added enormously to our knowledge 

 of the distribution of North American birds. This is particularly true 

 of western North America, especially of the Pacific coast region, where 

 Grinnell, W. K. Fisher, Swarth, and other members of the Cooper 

 Ornithological Club, have placed on record a vast amount of data 

 concerning the birds of this area. 



Besides furnishing material for the more philosophic phases of 

 faunal work, these monographs and local lists often treat also of the 

 migration of the birds with which they deal. Most important contribu- 

 tions to this subject have been made by the large and widely distributed 

 corps of observers acting under the direction of the Biological Survey, 

 which, under the authorship of Cooke, has published several important 

 bulletins on migration. Here also should be mentioned the significant 

 experiments of Watson upon the homing instincts of Terns, which are 

 referred to beyond (p. 54). 



Possibly, in no other branch of definitely directed ornithological 

 research has greater advance been made than in the study of the nesting 

 habits of birds. For the first time in the history of ornithology, trained 

 biologists have devoted an entire nesting season to the continuous 

 study of certain species, and the results obtained by Watson, Herrick, 

 Finley, and others, have, in a high degree, both scientific value and 

 popular interest. 



No small part of the educational value of work of this kind is due 

 to the photographic illustrations by which it is usually accompanied, 

 and bird study with a camera may be said to be the most novel and, 

 in many respects, the most important development in ornithological 



