do FOOD OF BOBOLESTK, BLACKBIRDS, AND GRACKLES. 



The increase of vegetable food other than grain and weed seeds 

 during August and September is due to the consumption of wild rice 

 {Zizania aguatica), which at this time forms quite an important item. 



In their insect diet the redwings do much good, for only a small 

 proportion of the species the}- eat are beneficial. More destructive 

 snout-beetles (weevils) are eaten by them than by any other birds that 

 the writer has examined, with the single exception of the bobolinks. 

 Other beetles and grasshoppers also constitute an important part of 



Fig. 5.— Diagram showing proportions of animal and vegetable food of red-winged blackbird in 

 each month of the year. The relative amounts of the different kinds of food are shown by varioasly 

 shaded urea.s. Thu.s, in Juno, useful insects arc represented by the broken-lined area at the bottom 

 of the column for that month, injurious insects by the horizontally shaded space, grain by the space 

 shaded with diagonal broken lines, and the other elements of foo<l in similar manner. The percent- 

 age of food (for example, of injurious insects), for a month, is not nece.s.sarUy indicated by the summit 

 of the curve, but by the space between the upper and lower cunes. (The figures in the margins 

 indicate percentages. ) 



the insect food. While there can be no doubt that the birds do con- 

 siderable damage when collected in large flocks, it is probalile that 

 such injury will become less and less as the area of cultivation 

 increases and the swamps where they breed are encroached upon and 

 drained, Avith a consequent reduction in the abundance of the species. 

 The Biological Survey has examined 1.088 stomachs of the redwing, 

 collected in every month of the year, and trom thirty States, the District 



