CHAPTER XXVIII 



THE EFFECT OF MAN ON THE DISTRIBUTION 

 OF OTHER ANIMALS 



Primitive man interfered with the conditions of his environment 

 relatively little, yet even his activities affected animal distribution 

 both locally and on a geographic scale. Civilized man changes his 

 environment greatly and alters it, in so far as he is able, according to 

 his needs and desires. He destroys many kinds of habitat and replaces 

 them with others, in part with such as would never be formed without 

 his aid, and would be unable to maintain themselves without his con- 

 stant intervention. At the same time, his measures alter the composition 

 of the animal associations ; he forces out some elements and introduces 

 others. He cultivates plants, maintains domestic animals, destroys 

 plants and animals which are harmful to his domestic races, and 

 attracts some forms, which find favorable conditions of life in his 

 neighborhood. He disposes of his wastes, sometimes intelligently, some- 

 times crudely, and in the latter case produces effects that are harmful 

 even to himself and to the plants and animals he favors. These de- 

 structive and creative activities give rise to man-modified or man- 

 dominated areas with their specialized and distinctive associations. 

 For an admirable study of this process the reader may be referred to 

 Ritchie's, The Influence of Man on Animal Life in Scotland, 1920. 



Deforestation. — An early step in wooded countries consists in the 

 clearing of land either for the lumber or to obtain soil free for the 

 cultivation of grains. This transformation has long been accomplished 

 in Europe, where the period of land-clearing extended from the seventh 

 to the thirteenth century ; in North America it occupied the eighteenth 

 and nineteenth centuries; the transformation of the well-forested states 

 of Ohio and Indiana into savanna country practically within the nine- 

 teenth century is an outstanding example of the deforestation activi- 

 ties of man. 



The area of virgin forest in territory now within continental bound- 

 aries of the United States was approximately 800,000,000 acres at the 

 time Columbus came to America, and was less than 100,000,000 acres, 

 according to estimates made available in 1931 by the U. S. Forest 

 Service. Although timber is still being cut in this country to permit 



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