BIRD ENEMIES INTRODUCED BY MAN 159 



increased greatly in numbers with the growth of 

 trees and parks, and the mountain bluebirds and 

 house finch were common occupants of bird-houses. 

 At the close of the winter's work there were never 

 left more than thirty or forty sparrows, and some- 

 times even fewer. 



When using the poisoned grain, after some of the 

 birds have been killed, other birds will be frightened 

 away, so that after each killing unpoisoned grain 

 should be fed till the birds become accustomed to 

 feeding there. Then the poisoned grain may be 

 used again. 



Trapping the sparrows. Trapping is one of the 

 most satisfactory methods of killing the sparrows, 

 and in some localities it is the only method that can 

 be used. It is a safer method than shooting or poison- 

 ing, and may be used in cities where the other meth- 

 ods would not be allowed. Sparrows caught in this 

 way may be used for food, if desired, and if native 

 birds are caught they can be set free. In using 

 poisons and traps special care should be taken to 

 see that our native birds are not killed by mistake. 



The combined use of traps and poisons is very ef- 

 fective. The trap may first be used to catch as many 

 of the flock as will enter it and then poison may be 

 used to kill the remainder. 



At least two types of traps may be used for catch- 

 ing sparrows, the nest-box trap and the bait trap. 

 The nest-box trap is so arranged that when the 



