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 bej^ond 

 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 

 14 209 



