398 



GENERAL ZOOLOGY 



particular farms are concerned, partly because of special condi- 

 tions. Its work in removing carrion and destroying insects is 

 serviceable, but it does so much damage to game, poultry, fruit, 

 and grain that it more than counterbalances the good, and should 



Seven days or less 



One to two weeks old 



Three weeks and older Adult 



Fig. 210. Diagrams showing relative amounts of different kinds of food 



eaten by crows of different ages 1 



be reduced in numbers. The grackle appears to be purely bene- 

 ficial to these farms during the breeding-season, and feeds ex- 

 tensively on weed-seed during migration, but at the latter time 

 it is very injurious to grain. The remaining species probably do 

 more good than harm and, except under unusual conditions, 



1 From Judd's Birds of a Maryland Farm. 



