464 SCIENCE OF HOME AND COMMUNITY 



Most of the work of eating weed seeds is done between 

 early autumn and late spring. During the summer, birds 

 feed largely on insects. This group of birds is beneficial 

 then in two ways, in eating insects and in eating weed seeds. 



Destroyers of rodent pests. Still a third way in which 

 birds help man is in destroying rodent pests, such as rats, 

 mice, and ground squirrels. The birds which are helpful in 

 this way are the hawks and the owls. These birds have 

 been greatly misjudged. Because a few hawks destroy some 

 poultry, the wrong notion has got abroad that all hawks 

 and owls are injurious. As a matter of fact only two com- 

 mon hawks, Cooper's hawk and the sharp-shinned hawk, 

 are injurious, and no common owl is. There are several 

 hawks which may occasionally take a chicken; but this is 

 the exception and it is made up many times by the good 

 they do. About ten per cent of the species of hawks and 

 owls are injurious, fifteen per cent are neutral, and seventy- 

 five per cent are beneficial. That is, more than seven times 

 as many species are beneficial as are injurious. 



Eight mice have been found in the stomach of a single 

 hawk. It seems fair to suppose that a hawk or owl would 

 destroy one thousand mice a year. It has been estimated 

 that a mouse will do two cents' worth of damage in a year, 

 so that these one thousand mice would do twenty dollars' 

 worth of damage. A hawk or owl, then, may be said to 

 be worth twenty dollars a year. 



Harm done by birds. A little harm is done by some 

 birds. Some birds, like the catbird and the cedar waxwing, 

 feed on cultivated fruit. Other birds, such as the English 

 sparrow, crow blackbird, and crow, feed on grain. About 

 one half of this is waste grain, and so should not be counted 

 against the bird. As already mentioned, some hawks and 

 owls destroy poultry. The worst offender is Cooper's hawk. 

 The sapsucker does damage to trees by drilling holes. 

 Sometimes the tree is killed, but the chief damage is due 



