172 Bryant, Birds as Grasshopper Destroyers. LApril 



represented in the table on p. 171. It should be here stated that 

 censuses of the bird population by species were taken and are used 

 in this calculation. The comparative numbers of the different 

 species were calculated by averaging the two censuses taken and 

 using the average per square mile as a multiplier. 



Although the table is probably far from accurate, yet it gives 

 some idea of the comparative destruction afforded by the different 

 species. It will be noted that such birds as the Bicolored Red- 

 wing and the Western Meadowlark, birds of small capacity, far 

 outrank in destructiveness birds with large capacity, because of 

 their greater numbers. Red-wings, Meadowlarks, Orioles, King- 

 birds, and Shrikes appeared to be feeding almost wholly upon 

 grasshoppers. Probably more than three-fourths of all the destruc- 

 tion by birds was accomplished by these five species. It should 

 be of interest to note that these are mainly birds against which 

 complaint is made upon the score of crop destruction. Even 

 though the Bicolored Red-wing averaged but nine grasshoppers 

 per bird in those examined, yet, on account of the numbers of 

 individuals, it must be considered the most valuable destroyer. 

 The one stomach of a Brewer's Blackbird examined probably does 

 not demonstrate the true character of this bird's food at this time, 

 for in other instances this blackbird has been found to be more 

 insectivorous than the Bicolored Red-wing. The average Western 

 Meadowlark must have consumed at least fifty grasshoppers a day. 



Certain birds examined and found to contain but few grasshop- 

 pers doubtless fed to a larger extent on these insects when they were 

 of smaller size. The swallows, for instance, owing to their small 

 size, were unable to eat a large grasshopper. If the investigation 

 could have covered the entire time of the outbreak, it would proba- 

 bly have been fbund that certain birds were far more efficient 

 destroyers when the insects were small than when they became 

 larger. 



Fortunately some material collected at Los Banos the same 

 month in 1911 was available. This afforded a comparison of the 

 food of the Western Meadowlark and the Bicolored Red-wing in 

 two successive years. As grasshoppers were less numerous in the 

 summer of 1911, it has been possible to obtain information as to the 

 comparative destruction by these birds when grasshoppers were in 



