tlie Value of Birds to Man. 93 



Vegetation is the prime requisite for the perpetuity of all 

 other forms of life upon the earth. It is the only form in 

 organic nature that does not war u})on other forms. The 

 greatest known enemy to vegetation is insect life ; while 

 bird life, by virtue of its predominating insect diet, wields 

 a most important balance of power against the ravages o£ 

 this the chief pest of vegetation. 



This is the principal mission of the bird in preserving 

 the balance of Nature's forces ; and when we remember 

 that birds are distinguished from all other animals by 

 organs of perfect flight, when we remember that the sense 

 of sight in birds is developed to a degree unparalleled 

 in the animal world, when we remember the surpassing 

 breathing-power possessed by birds, their wonderful mus- 

 cular strength and activity, the high temperature ^nd rapid 

 circulation of their blood, and, as necessary fuel for all 

 these fires, their extraordinary capacity for assimilating 

 food, we must admit that these marvellous cr 'atures are 

 admirably fitted to pursue and capture their nat iral prey, 

 or, by making earth-wide sweeps from zone to zone, to 

 follow the seasonal ebb and flow of the tide of ijisoct life. 

 We must admit that no other class of animals could fiU 

 their peculiar place. 



Number and Repropuctiveness of Insects. 



That you may see how essential the bird is as a part of 

 Nature's great plan I propose making brief mention of the 

 enormous number of insect species, of their stupendous 

 powers of reproduction, and of their insatiable voracity. 



The number of insect species is greater b^ far than that of 

 the species of all other living creatures combined. Over 

 300,000 have been described, and it is considered not 

 improbable that twice that number remain to be described. 

 Practically all living animals, as well as most plants, 

 furnish food for those incomputable hordes. More than 

 this, Kirby, in the ' Introduction to Entomology,' devotes 

 no less than five entire epistles to the injuries wo sustain 



8* 



