THE VERTEBRATE ANIMALS 307 



should be welcomed by all thinking Americans. Without the 

 birds the farmer would have a hopeless fight against insect pests. 

 The effect of killing native birds is now well seen in Italy 

 and Japan, where insects are increasing and do greater damage 

 each year to crops and trees. 



Of the eight hundred or more species of birds in the United 

 States, only two species of hawks (Cooper's and the sharp-shinned 

 hawk), the great horned owl, the cowbird, and the English spar- 

 row may be considered as enemies of man. 



The English Sparrow. The English sparrow is an example of 

 a bird introduced for the purpose of insect destruction, that has 

 done great harm because of its relation 

 to our native birds. Introduced at 

 Brooklyn in 1850 for the purpose of ex- 

 terminating the cankerworm, it soon 

 abandoned an insect diet and has driven 

 out most of our native insect feeders. 

 Investigations by the United States 

 Department of Agriculture have shown 

 that in the country these birds and 

 their young feed to a large extent upon 

 grain, thus showing them to be injurious The proportions of food of the 



vr , English sparrow. 



to agriculture. Dirty and very prolific, 



it already has worked its way from the East as far as the Pacific 

 coast. In this area the bluebird, song sparrow, and yellowbird 

 have all been forced to give way, as well as many larger birds of 

 great economic value and beauty. The English sparrow has be- 

 come a national pest, and should be exterminated in order to save 

 our native birds. It is feared in some quarters that the English 

 starling which has recently been introduced into this country may 

 in time prove a pest as formidable as the English sparrow. 



Geographical Distribution and Migrations. Most of us are 

 aware that some birds remain with us in a given region during the 

 whole year, while other birds appear with the approach of spring, 

 departing southwards with the warm weather in the fall of the 

 year. Such birds we call migrants, while those that remain the 

 year round are called residents. 



In Europe, where the problem of bird migration has been 



