234 



THE ANIMALS AND MAN 



or beneficial to man. Casual observation shows that birds 

 eat worms, grains, seeds, fruits, insects. A single species 

 often is both fruit-eating and insect-eating. Do fruits or do 

 insects compose the chief food-supply of the species? To 

 determine this more than casual observation is necessary. 



FIG. 126. Horned larks, Olocons alpesiris, and snowflakes, Pleclrophenax 

 nivalis. (Photograph by H. W. Menke; permission of The Macmillan 

 Co.) 



The birds must be watched when feeding at different sea- 

 sons. The most effective way of determining the kind of 

 food which the bird takes is to examine the stomach of many 

 individuals taken at various times and localities. Much 

 work of this kind has been done, especially by investigators 

 connected with the Division of Biological Survey of the 

 United States Department of Agriculture, and pamphlets 

 giving the results of these investigations can be had from 



