BIRDS IN RELATION TO AGRICULTURE 183 



Although, as I have already pointed out, the majority of 

 hawks are useful birds, several species are destructive to 

 bird Ufe and should be dealt with accordingly. Among the 

 destructive species are the following: Cooper's hawk, the 

 sharp-shinned hawk, the pigeon hawk, and the duck hawk. 

 Fortunately these species are not very abundant. 



3. Provision of Fruit-bearing Trees and Shrubs 



The vegetable food of many of our insectivorous birds 

 under natural conditions consists largely of wild fruits and 

 berries. Such birds as robins and bluebirds eat a greater 

 proportion of animal food during the spring and summer, 

 but as insects become less abundant and wild fruits ripen 

 in the fall, vegetable food appears to predominate. When 

 man changes the natural environment by planting culti- 

 vated fruits, such as cherries, currants, raspberries, and 

 strawberries, birds such as robins are apt to prefer the larger 

 and more succulent cultivated varieties to the wild ones. 

 When this happens the owner of the fruit is apt to forget 

 the benefits that the birds have conferred upon him earlier 

 in the year by destroying the insect enemies of his crops, and 

 is apt to deal with them accordingly. There are, however, 

 alternative methods of preventing such damage. I have 

 already pointed out that it is cheaper to protect cultivated 

 fruit trees against the attacks of useful birds such as robins, 

 than to permit insects to increase uncontrolled by birds. 

 Another method of reducing the damage done by birds to 

 cultivated fruits is to provide them with wild fruits as a 

 small return for their services in destroying injurious insects. 



The planting of fruit-bearing trees and shrubs in gardens 

 and parks and bird sanctuaries is a very effectual method 

 of attracting birds to a place. Lovers of birds and gardens, 

 when planting gardens and parks, should, therefore, give 

 preference to those species of trees and shrubs that bear 



