6 ECONOMIC VALUE OF BIRDS. 



in devouring small rodents, in destroying the seeds of 

 harmful plants, and in acting as scavengers. 



Leading entomologists estimate that insects cause an 

 annual loss of at least two hundred million dollars to the 

 agricultural interests of the United States. The state- 

 ment seems incredible, but is based upon reliable sta- 

 tistics. This, of course, does not include the damage 

 done to ornamental shrubbery, shade and forest trees. 

 But if insects are the natural enemies of vegetation, birds 

 are the natural enemies of insects. Consider for a mo- 

 ment what the birds are doing for us any summer day, 

 when insects are so abundant that the hum of their united 

 voices becomes an almost inherent part of the atmosphere. 



In the air Swallows and Swifts are coursing rapidly 

 to and fro, ever in pursuit of the insects which constitute 

 their sole food. When they retire, the Nighthawks and 

 Whip-poor-wills will take up the chase, catching moths 

 and other nocturnal insects which would escape day-flying 

 birds. The Flycatchers lie in wait, darting from ambush 

 at passing prey, and with a suggestive click of the bill 

 returning to their post. The "Warblers, light, active crea- 

 tures, flutter about the terminal foliage, and with almost 

 the skill of a Hummingbird pick insects from leaf or 

 blossom. The Yireos patiently explore the under sides of 

 leaves and odd nooks and corners to see that no skulker 

 escapes. The Woodpeckers, Nuthatches, and Creepers 

 attend to the tree trunks and limbs, examining carefully 

 each inch of bark for insects' eggs and larvas, or exca- 

 vating for the ants and borers they hear at work within. 

 On the ground the hunt is continued by the Thrushes, 

 Sparrows, and other birds, who feed upon the innumer- 

 able forms of terrestrial insects. Few places in which 

 insects exist are neglected ; even some species which pass 

 their earlier stages or entire lives in the water are preyed 

 upon by aquatic birds. 



