360 ECONOMIC IMPORTANCE OF ANIMALS 



Without the birds the farmer would have a hopeless fight against 

 insect pests. The effect of killing native birds in great numbers is 

 now well seen in Italy and Japan, where insects have increased 

 and do great damage to crops and trees. 



Birds eat Weed Seeds. — Not only do birds aid man in his 

 battles with destructive insects, but many birds eat the seeds of 

 weeds also. Our native sparrows (not the English sparrow), the 

 mourning dove, bobwhite, and other birds feed largely upon the 

 seeds of many of our common weeds. This fact alone is sufficient 

 to make birds of great economic importance. 



Other Useful and Harmful Birds. — Not all birds are seed or in- 

 sect eaters. Some, as the cormorants, ospreys, gulls, and terns, are 

 active fishers. Near large cities especially gulls act as scavengers, 

 destroying much floating garbage that otherwise might be washed 

 ashore to become a menace to health. The vultures of India and 

 semitropical countries are of immense value as scavengers. Birds 

 of prey (hawks and owls) eat living mammals, including many 

 rodents ; for example, field mice and rats. 



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

 States, the only enemies of man are six species of hawks (Cooper's 

 and the sharp-shinned hawk in particular), and the great horned 

 owl, which prey upon useful birds ; the sapsucker, which kills or 

 injures many trees ; the bobolink, which destroys yearly $2,000,000 

 worth of rice in the South ; the crow, which feeds on crops as well 

 as insects ; and the English sparrow. 



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. In- 

 troduced at Brooklyn in 1850 for the purpose of exterminating the 

 cankerworm, it soon abandoned an insect diet and has driven 

 out most of our native insect eaters. Investigations by the United 

 States Department of Agriculture show that in the country these 

 sparrows and their young feed to a large extent upon grain, thus 

 showing them to be injurious to agriculture. Dirty and very 

 prolific, they have long since worked their 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 



