THE UTILITY OF BIEDS. 



INTRODUCTION. 



There is a continual demand for literature setting forth the 

 usefulness of our native birds. In the introductory chapter to 

 my "Useful Birds and their Protection" the subject of the 

 utility of birds in nature was treated at some length, but as 

 that work, having passed through several editions, is now out 

 of print, it seems necessary to treat the subject briefly as an 

 introduction to this bulletin, so that the reader, as a necessary 

 preliminary before examining the evidence regarding the value 

 of birds to man, may realize something of their function in nature. 



Our globe teems with life. Uncounted myriads of plants and 

 animals encompass the earth, dwell in the sea, or float upon the 

 invisible waves of the atmosphere. Earth's animals and plants 

 vary in size from that of the infinitesimal atom, too small for 

 the human eye to discern through the most powerful micro- 

 scope, up to that of the mighty whale, 90 feet in length, and 

 the great sequoia of California, 325 feet high, or the giant 

 eucalyptus of Australia, reaching a height of 470 feet. 



Let one examine carefully a few square yards of grassland in 

 summer and see how many individuals of plant and animal life 

 he will find. 1 Let him look thoroughly over the bark of a single 

 tree and note how many insect species are living on or under it. 

 During a few hours of one July night off the Maine coast we 

 saw in the dark, flashing waters myriads of fish limned in 

 phosphorescent light darting away from the prow of our vessel. 

 For 10 miles we plowed through their countless, never-ending 

 hordes, apparently all of one size and one species, and no one 

 knows how much farther their hosts extended. Yet we could 

 not have seen them at all but for the light produced by the 

 countless millions of Noctilucse which illumined every moving 

 thing in those waters. The numbers of these tiny animals have 

 been estimated at 30,000 to each cubic inch. How many of 

 these atomies, representing only one form of life, existed in that 

 sea through which those millions of fish were swimming? 



1 Mr. W. L. McAtee found 1,254 individual forms of insects and other small animal life, and 

 3,113 seeds on 4 square feet of meadow land (Science, New Series, Vol. XXVI, No. 666, Oct. 4, 

 1907, p. 447). 



