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Wildlife Leaflet 224 
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Reissued November 1942 4 
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BIRDS AS A FACTOR IN CONTROLLING INSECT DEPREDATTONS 
By Clarence Cottam and Francis M. Uhler, Biologists,Economic Wildlife 
Investigations, Division of Wildlife Research. 
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That. North Ameiican birds are regarded as a priceless national heritage 
is shown by the fact that allbbut a relatively few species (or groups) are 
protected by Federal law, by international treaty with Canada (@reat Britain) 
and Mexico, or by the laws of the States or the Canadian Provinces. 
Birds are useful as protectors of crons and forests through their feed— 
ing on destructive insects, as part of Nature's great balancing mechanism, 
as scavengers, as game, food, or articles of commerce, or merely as objects 
of beauty and interest. To a people of Sentiment, wildlife or other 
objects of nature need not be associated with the dollar sign in order to 
receive protection and encouragement. We agree with Emerson that "if eyes 
were made for Seeing, then Beauty is its own excuse for being." The™ 
esthetic and recreational values of birds, though largely intangible, are 
gust as real as bank accounts or interest. on stocks and bonds, Like a 
masterpiece of art or an orchestral symphony, they uplift the soul and give 
meaning and purpose to life. Man is rejuvenated both in spirit and in body 
by a day afield, enjoying the charm and beauty of the songs of birds, study- 
ing the grace and rhythm of their movements, and parteking of their contagious 
joyousness, HE, H. Forbush has well said that "the beauty of birds, the. music 
of their song, the weird wildness of their call, the majesty of their soar- 
ing flight, and the mystery of their migration, always have been subjects of 
absorbing interest to poets, artists and lovers of nature." Certainly much 
of the appeal, beauty, and charm of literature, art, and music would be lost 
if Shopn on their alliusrenms towbards', 
Although their esthetic and recreational worth constitutes, perhaps, 
their greatest value to mankind, birds have also tremendous economic poten= 
tialities to which consideration must be given, Probably more than half 
the food of the 1,400 species and varieties of North American birds con- 
sists of insects. That the aggregate number of insects consumed is enor- 
mous nO One Can Question. Yet the Significance and effectiveness of such 
feeding as a factor in insect control are matters far more difficult to 
appraise. Ordinarily, climate, disease, and parasites are equally or pos- 
Sibly more important as natural checks on most pest species of insects, but 
entomologists and ornithologists agree that the insectivorous birds, through 
NOTE; This leaflet supersedes Wildlife Lucflet BS-162, issued in 
Mey 1940 by the Bureau of Biological Surveye 
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