142 Bird -Lore 



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 experiments 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 con- 

 ducted psychological investigations vipon certain species; and Watson has 

 pursued similar studies upon the Noddy and the Sooty Tern in nature. The 

 highly original researches of Thayer 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 investi- 

 gations 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 important phases of research during the period under con- 

 sideration. While based, primarily, on field work in observing as well as in 

 collecting, special training in laboratory methods is required to make the analy- 

 ses 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 addition 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 contributions 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. 



Possibly, in no other branch of definitely directed ornithological research 

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



mi 



