FOES AMONG THE BIRDS 101 



percentage that grain forms of the whole food, are 

 shown in the following table: — 



Name of bird Per cent of the whole 



food that grain forms 



English sparrow 74 



Crow blackbird 46 



Crow 29 



Cowbird 16 



Red-winged blackbird 14 



The crow does damage chiefly to the sprouting 

 grain, the other birds to the maturing crop. The 

 crow and crow blackbird do their chief damage to 

 corn. The red-winged blackbird is especially de- 

 structive in the Mississippi Valley. Favorable con- 

 ditions for breeding are found in the sloughs and 

 marshes, and after the young have left the nest, 

 large flocks may settle upon grain-fields and do dam- 

 age, both by eating the grain and by breaking down 

 the straw and making it difficult to cut. 



These birds do not seem to be especially fond of 

 grain as compared with wild foods, but are driven to 

 eating it on account of an excessive number of birds 

 of the same kind living in a limited area. In time 

 a proper equilibrium will probably be established, 

 when the birds will exist in smaller numbers and 

 hence do less damage. A study of the months when 

 this grain was eaten and of the places where it was 

 collected shows that it was probably at least half 

 waste grain collected in the fields or on the ground 

 after the grain had been harvested, so that this 



