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ANIMAL BIOLOGY 



especially destructive of insects such as grasshoppers, 

 Colorado potato beetles, chinch bugs, army worms, cotton 

 worms, and striped cucumber beetles. Forbush in his 

 valuable book on " Useful Birds and Their Protection" 

 says of the quail that "it is probably the most effective 

 enemy of the Colorado potato beetle." Certain species 

 of birds, such as owls and some kinds of hawks, perform 

 a valuable service in destroying micej ground squirrels, 

 gophers and other small mammals that are a nuisance to 

 the farmer. Other birds are helpful to the farmer by 

 destroying large quantities of weed seeds. And while 



7 DAYS OR LESS ADULT 



FIG. 158. Diagram showing proportions of food of American crow 

 (Corvus americanus) , young and adult. (After Judd.) 



many species are destructive to grains and fruits, the 

 damage they do is usually outweighed by the benefit they 

 confer in destroying weed seed and insects. Careful 

 investigation has shown that several kinds of birds com- 

 monly deemed injurious are on the whole beneficial. 

 The larger owls which are often shot for their occasional 

 attacks upon poultry are on the whole very valuable 

 birds for reasons above named. There are several hawks 

 which are beneficial since their food consists almost 

 exclusively of small mammals and insects. Others are 

 of more doubtful utility, since they prey upon birds as 



