sent, therefore, the results of the investigations of economic ornithologists into 

 the food habits of our birds. But before giving in detail the studies of these 

 specialists it will be well to outline in a general way how birds may be valuable 

 or injurious to man. 



Birds are of value to the State chiefly through the services they render in 

 (1) eating harmful insects, their eggs and larvae; (2) in eating the seeds of 

 noxious weeds; (3) in devouring field mice and other small mammals which 

 injure crops; (4) in acting as scavengers. The appended outline of the bird's 

 relation to the forester, fruit-grower, farmer, and citizen will enable us to 

 appreciate its economic importance. 



The agriculturist, in producing an artificial condition in the plant world, 

 creates also an unnatural state of affairs among the insects that find a new food 

 in the outcome of his husbandry and among the birds that prey upon tlies6 

 insects. But between birds and forests there exist what may be termed primeval, 

 economic relations. Certain forest trees have their natural insect foes to which 

 they furnish food and shelter ; and these insects, in turn, have their natural 

 enemies among the birds to which the trees also give a home. Here, then, we 

 have an undisturbed set of economic relations: (1) the tree; (2) the insect 

 which lives in the tree, preys upon it, and may assist in the fertilization of its 

 blossoms; (3) the bird which also finds a home in the tree and, feeding upon 

 insects, prevents their undue increase. Hence, it follows that the existence of 

 each one of these forms of life is dependent upon the existence of the other. 

 Birds are not only essential to the welfare of the tree, but the tree is necessary 

 to the life of the bird. Consequently, there has been established what is termed 

 "a balance of life" wherein there is the most delicate adjustment between the 

 tree, the insect, the bird and the sum total of the conditions which go to make 

 up their environment. The more trees, the greater the number of insects, and, 

 hence, an increase not only in food supply for the birds, but an increase in the 

 number of nesting-sites. 



Destroy the trees and the insect finds new food in the crops of the farmer, 

 but the birds, although food is still abundant, lose their home when the tree 

 falls, and, lacking the nesting-sites and protection from their enemies once 

 found in its spreading branches, they soon perish. 



What we may call artificial forest conditions are to be found in parks, 

 squares, village streets, and in our gardens. Here forest trees may find a suit- 

 able soil, but birds are often less abundant in such localities than in the forest, 

 and consequently the trees growing in them are notably less healthy than forest 

 trees. It is in these semi-domesticated trees that a scourge of injurious insects 

 most often occurs, occasionally to be followed by a marked increase of their 

 bird enemies, which are attracted by the unusual abundance of food. Caroline 

 G. Soule writes : 



"Last year, at Brandon, Vermont, the tent-caterpillars were so abundant 

 as to be a serious injury and annoyance. They lay in close rows, making wide 



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