﻿Common Birds in Relation to Agriculture. 513 



these birds in the State of Iowa. Upon the basis of one- 

 fourth of an ounce of seed eaten daily by each bird, and 

 supposing that the birds averaged ten to each square mile, 

 and that they remain in their winter range two hundred 

 days, we shall have a total .of 1,750,000 pounds, or 875 

 tons, of weed seeds consumed by this one species in a sin- 

 gle season. Large as these figures may seem, they cer- 

 tainly fall far short of the reality. The estimate of ten 

 birds to a square mile is much within the truth, for the 

 tree sparrow is certuinly more abundant than this in 

 winter in Massachusetts, where the food supply is less 

 than in the Western States, and I have known places in 

 Iowa where several thousand could be seen within the 

 space of a few acres. This estimate, moreover, is for a 

 single species, while, as a matter of fact, there are at least 

 half a dozen birds (not all sparrows) that habitually feed 

 on these seeds during winter. 



Farther south the tree sparrow is replaced in winter by 

 the white-throated sparrow, the white-crowned sparrow, 

 the fox sparrow, the song sparrow, the held sparrow and 

 several others ; so that all over the country there are a 

 vast number of these seed eaters at work during the 

 colder months reducing next year's crop of worse than 

 useless plants. 



In treating of the value of birds, it has been customary 

 to consider them mainly as insect destroyers ; but the fore- 

 going illustration seems to show that seed eaters have a 

 useful function, which has never been fully appreciated. 



THE ROSE-BREASTED GROSBEAK. 



( Zamelodia ludoviciana. ) 



The beautiful rose-breasted grosbeak breeds in the 

 northern half of the United States east of the Missouri 

 Eiver, but spends its winters beyond our boundaries. 

 Unfortunately, it is not abundant in New England, and 



