work, supplemented by stomach examinations of birds taken in many 

 different parts of the State each month in the year. Both of these 

 lines of investigation are important as they each supplement the other. 



A thorough knowledge of the nature and extent of the damage done 

 by certain of our birds, combined with a full understanding of their 

 value to the agriculturist as insect and weed-seed destroyers, such as 

 is being made available by this investigation, will be of inestimable value 

 to the rancher. For certain it is that the successful farmer of today 

 and of the future will have to be able to estimate the status of the birds 

 on his farm with reference to his own interests and to those of the 

 community, and adopt measures accordingly. 



Nor should the results of the investigation be interesting to the agri- 

 culturist alone. The United States Supreme Court has ruled that game 

 and wild birds belong to the people and not to individuals. Informa- 

 tion as to the value of this asset becomes important, therefore, just 

 as information as to the value of forests is important. Consequently 

 the present investigation deserves the interest and support of not alone 

 those directly involved, but of all those interested in the conservation 

 of a national resource. 



Through the co-operation of the University of California, there have 

 been afforded not only suitable laboratories for the work of stomach 

 examination, but also the advice and help of Professor C. A. Kofoid 

 of the Department of Zoology, Mr. Joseph Grinnell, Director of the 

 Museum of Vertebrate Zoology, and Professor C. W. Woodworth of 

 the Department of Entomology, as well as others connected with that 

 institution. 



THE INVESTIGATION AS TO METHOD. 



FIELD INVESTIGATION. A STUDY OF THE BIRD AT THE SCENE OF ACTION. 



The attempt has been made to combine the best of the methods here- 

 tofore used by economic ornithologists, and to supplement these methods 

 by new ones of value. We believe the following improved methods in 

 determining the economic status of birds will tend to a nearer Attain- 

 ment of the end sought a reliable estimation of the economic value 

 of a bird. 



1. Complete data as to the birds collected for stomach examination is 

 furnishing information as to the variation in kind, amount, and prefer- 

 ence of food of a bird, according to the hour, day, week, month, year, 

 environment, and sex. 



2. The use of a combination of methods of stomach examination is 

 tending to decrease personal error, and is allowing a more accurate 

 determination of the food habits. 



3. The food capacity of different birds is being determined by a meas- 

 urement of the volume of food in cubic centimeters. 



