WILD LIFE OF ORCHARD AND FIELD 



little affected by the civilizing of the country, either 

 in numbers or habits, while others increase rapid- 

 ly on the first settlement of a region, and then de- 

 crease again. Of this class are the prairie-hen 

 and other game, and the mallard. "They find 

 abundance of food in the corn and wheat fields; 

 while the population is sparse and larger game so 

 abundant, they are hunted very little; but as the 

 population increases they are gradually thinned 

 out, and become in some cases exterminated. Other 

 birds, as the quail, are wholly unknown beyond 

 the frontier, and only appear after the country 

 has been settled a short time. Still others, wood- 

 land species, appear in regions where they were 

 never known before, as groves of trees are plant- 

 ed, and thick woods spring up on the prairies as 

 soon as the ravages of the fires are checked." 



Striking examples of how some of our birds 

 have accepted this tacit invitation to make men 

 their confidants occur in the history of the Amer- 

 ican swallows and swifts. Our purple martins 

 spread themselves in summer all over North Amer- 

 ica, but are becoming rare in the New England 

 States, whence they seem to have been driven by 

 the white-bellied swallows, which have gradually 

 grown more numerous, and which, preceding the 

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