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BULLETI:N' 1355, U. S. DEPABTMENT OP AGRICULTURE 



SUMMARY 



There can be no reasonable doubt that with an annual consumption 

 of 42.25 per cent of caterpillars and moths, the yellow-throated 

 vireo is to be classed as a beneficial bird. Adding to this the 7.62 

 per cent representing bugs, most of which are injurious, and the 10.46 

 per cent of distinctly injurious beetles, the total of 60.53 per cent 

 is a fair estimate of injurious insects in the bird's food. To offset 

 this, only 0.62 per cent is made up of the benficial ladybird beetles. 

 The rest of the food is neutral economically and may be passed with 

 this mention. This is a record to commend the yellow-throated 

 vireo, and one that is not closely approached by other birds of this 

 family. 



THE BLUE-HEADED VIREOS 



Lanivireo solUarius, subspp. 



The blue-headed vireos, or, as they are sometimes called, the 

 solitary vireos, are of fair abundance over a wide range, including all 

 of the United States, most of Canada, and parts of Mexico and Lower 

 California. The material used in this study includes 306 well-filled 

 stomachs, collected in all months except December, January and 

 November are represented by but 8 and 9 stomachs, respectively, 

 whereas the greatest number for any one month, 79, is for May. 

 Twenty-three other stomachs, only partially filled, gave some addi- 

 tional data regarding food items. 



The blue-heads eat about twice as much vegetable food as the 

 yellow-throat (3.68 per cent), but otherwise the diet is similar in its 

 constituent items. (See fig. 6.) 





/^OA/7^/¥Ly y^OO^O Qy^ ^^/V/AZ^/Et? <^OZ./7>9ye/0,S' 



Fig. 6.— Monthly proportions of the various items in the food of the blue-headed vireos (Lanivireo soliiariiis , 

 subspp.), based on the analysis of the contents of 306 stomachs, with the average of each item for the year 



