i go 



ECONOMIC ZOOLOGY 



years, upon the food of our common birds. In determining the eco- 

 nomic status of any bird it is necessary to know of what its food consists 

 at all seasons of the year. A bird may be a nuisance for a few weeks, 

 as a fruit eater, for example, while all the rest of the year it may be 

 highly beneficial to the farmer as an eater of weed seeds and of destruc- 

 tive insects. 



The food of birds is determined in two ways: the more pleasant 

 but less accurate method is to watch them feed and note what they eat; 

 the less pleasant but more accurate method is to kill the birds at dif- 



PIG. 118. The hairy woodpecker, Dryobates villosus, at breakfast. X;Hj. 

 (From Daugherty, Principles of Economic Zoology, after Biological Survey, U. S, 

 Dept. of Agriculture.) 



ferent seasons and in different places and examine carefully the stomach 

 contents. The latter method, which has been extensively employed 

 by the Biological Survey of the Department of Agriculture, gives not 

 only the kinds of foods eaten but the proportions of each kind. By such 

 studies it has been determined that while few species of birds, perhaps, 

 are entirely beneficial, the vast majority of our common birds do far 



