30 FOOD OF BOBOLINK, BLACKBIRDS, AND GRACKLES. 



In view of tlie fact that so much has been said in condemnation of 

 the cowbird's parasitic habits, it may not be out of place to inquire 

 whether this parasitism is necessarily as injurious as has been claimed. 

 When a single young cowbird replaces a brood of four other birds, 

 each of which has food habits as good as its own, there is, of course, 

 a distinct loss; but, as already shown, the cowbird must be rated high 

 in the economic scale on account of its food habits, and it must be 

 remembered that in most cases the birds destroyed are much smaller 

 than the intruder, and so of less eflfect in their feeding, and that two 

 or three cowbird eggs are often deposited in one nest. 



The question is a purel}' economic one, and until it can be shown 

 that the J^oung birds sacrificed for the cowbirds have more economic 

 value than the parasite, judgment must be suspended. 



THE YEIiLOW-HEADED BLACKBIRD. 



{Xant]i(/(rj>}tah(.'i .nivthorrpltdliis.) 



The 3" ellow- headed blackbird is locally distributed throughout the 

 Western United States, whore it frequents marshes and sloughs, but 

 avoids the more arid deserts, extensive forests, and wooded mountains. 

 Its range in summer extends from southern California through north- 

 ern Arizona and New Mexico to Indiana, and northward into the 

 Canadian Provinces. It winters in the southern part of its range and 

 on the table-lands of jMexico. Stragghu's have boon found from Clrecn- 

 land to Cul)a. 



Its breeding habits are nuicli like those of the redwing, but it is 

 usually less abundant than that l)ird. It is gregarious and resorts to 

 marshes to l)uild its nest, which is ver^' similar to that of the redwing, 

 and similarly placed. Although it breeds in marshes, it does not by 

 any means confine itself to them in its search for food, but forages far 

 afield, visiting corncribs, grainfields, and l)arnyards. The writer's first 

 experience with the yellow-headed blackbird was on the prairies of 

 Neljraska, where flocks visited the railway then in process of construc- 

 tion, running about among the feet of the nmlos and horses in search 

 of grubs and wonns exposed l)v the plow and scraper, and all the time 

 uttering their striking gutteral notes (almost precisely like those of a 

 brood of .suckling pigs). In their habit of visiting barnyards and hog 

 pastures they resemble cowbirds nuu'h more than redwings. AVhen 

 the breeding season is over the}' often visit grainfields in large flocks, 

 and become the cause of much complaint In' Western farmers. 



The investigation of their food is founded upon an examination of 

 138 stomachs received from ten of the Mississippi Valley States, and 

 from California and Canada, and collected during the seven months 

 from April to October, inclusive (see p. 73). While decidedlj' too few 

 to give entirely reliable results, they ma}' furnish some preliminary 



