BIRDS 



277 



sistance to the air. The bones are filled with air spaces and 

 there are large air sacs in the abdomen connected with the 

 lungs, all of which tend to lessen the specific gravity of 

 the body. 



Food and economic importance. — The food eaten by the 

 English sparrow and the bearing this has upon its economic 

 importance has been given considerable attention by the 

 United States Department of Agriculture. In all, 632 

 stomachs of these birds, of which 50 were nestlings, have 

 been examined and the contents 

 of each 'accurately determined. 

 Figure 188 gives a graphic repre- 

 sentation of the result of this 

 investigation. Two per cent of 

 the year's food consists of animal 

 matter, chiefly insects ; 24 per cent 

 of grass and weed seeds, and 74 

 per cent of grain. The fact that 

 grain was found to constitute fig. iss.- Diagram showing 

 nearly three fourths of the food 

 of the adult sparrows has brought 

 merited condemnation upon this small but abundant bird. 

 Moreover, the results of the examination of the 50 stomachs 

 of nestlings bring additional reproach upon this sparrow. 

 The food of the nestlings of our native sparrows, so far 

 as we know, consists exclusively of animal food, mainly 

 insects. In contrast with this it was found that 33 per 

 cent of the food of the aforementioned 50 nestlings was 

 composed of grain. In justice, however, it must be added 

 that 65 per cent of the food consisted of insects, chiefly 

 grasshoppers. Taking this record as a whole, we must 

 class the English sparrow as decidedly injurious to agri- 



proportions of food of an 



English sparrow. 



