BIOLOGICAL SUEVEY. 239 



BIOLOGICAL INVESTIGATIONS. 



Biological investigations have been mainly along lines "which sup- 

 ply information essential to the effective administration of the vari- 

 ous activities of the bureau, including the enforcement of the Lacey 

 Act regulating importation and shipment of game, the Federal mi- 

 gratorj^-bird law, maintenance of bird and mammal reservations, and 

 economic investigations concerning the relations of birds and mam- 

 mals to agriculture, stock-growing, and forestry. In securing in- 

 formation of practical value in connection with the conservation of 

 our bird and mammal life, particularly in regard to the species of 

 economic importance, a card-index file, consisting largely of unpub- 

 lished data gathered by the field parties of the bureau, has been 

 greatly increased. Manuscript field notes on mammals gathered dur- 

 ing the past 25 years have been arranged in the card files, and for the 

 first time have become readily available for reference. The files 

 concerning North American birds now contain more than 1,000,000 

 cards. 



DISTRIBUTION AND MIGRATION OF BIRDS. 



Eegular reports on the migration of birds have been received dur- 

 ing the year from all parts of the United States from more than 300 

 volmiteer observers and some from Canada and Alaska. These 

 furnish invaluable records in connection with the administration of 

 the migratory-bird law. Office investigation has included the colla- 

 tion and preparation for publication of material concerning the 

 distribution and migration of gulls, terns, and rails and their allies 

 and several other groups of birds. As rapidly as possible facts 

 gathered in investigations of bird migration are being published that 

 the information may be available for the use of those interested, par- 

 ticularly in connection with the formulation of laws for the protec- 

 tion of birds by the various States. 



BIRD CENSUS. 



The data secured by the first bird census, made in the spring of 

 1914, were studied and a preliminary report prepared and published. 

 The results proved of extreme interest and showed the possibility of 

 largel}^ increasing the bird life throughout the country. A second 

 national bird census was announced for the spring of 1915, and more 

 than 200 voluntary observers took part in it, covering the country 

 more generally than in the preceding year. The results of this work 

 also will be prepared for publication. One of the most valuable facts 

 developed by the bird census was that where an effort is made to pro- 

 tect birds from their enemies there is a notable increase of the bird 

 population. 



DISTRIBUTION MAPS OF BIRDS AND MAMMALS. 



Work was continued on the preparation of distribution maps show- 

 ing the area occupied by each species of bird and mammal in North 

 America. A set of distribution maps of certain economically impor- 

 tant birds and mammals was completed and is being exhibited at the 

 Panama-Pacific International Exposition at San Francisco. Maps 

 showing the present and former ranges of the various species of game 

 birds and mammals have proven extremely useful in connection with 

 restocking areas in which the various species have become extinct. 



