30 FOOD OF BOBOLINK, BLACKBIRDS, AND GRACKLES. 
In view of the 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 xo of less effect in their feeding, and that two 
or three cowbird eggs are often deposited in one nest. 
The question is a purely economic one, and until it can be shown 
that the young birds sacrificed for the cowbirds have more economic 
value than the parasite, judgment must be suspended. 
THE YELLOW-HEADED BLACKBIRD. 
(Xanthocephalus xanthocephalus. ) 
The yellow-headed blackbird is locally distributed throughout the 
Western United States, where 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 Mexico. Stragglers have been found from Green- 
land to Cuba. 
Its breeding habits are much like those of the redwing, but it is 
usually less abundant than that bird. It is gregarious and resorts to 
marshes to build its nest, which is very similar to that of the redwing, 
and similarly placed. Although it breeds in marshes, it does not by 
any means contine itself to them in its search for food, but forages far 
afield, visiting corncribs, grainfields, and barnyards. The writer’s first 
experience with the yellow-headed blackbird was on the prairies of 
Nebraska, where flocks visited the railway then in process of construc- 
tion, running about among the feet of the mules and horses in search 
of grubs and worms exposed hy 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 much more than redwings. When 
the breeding season is over they often visit egraintields in large flocks, 
and become the cause of much complaint by 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 decidedly too few 
to give entirely reliable results, they may furnish some preliminary 
