g4 FOOD OF BOBOLINK, BLACKBIRDS, AND GRACKLES. 
species most frequently imposed upon, but occasionally larger ones are 
victimized. Major Bendire enumerates 90 species in whose nests the 
cowbird’s eggs have been found. The largest of these are the mourn- 
ing dove (Zenaidura macroura) and the meadowlark (Sturnella magna.)! 
That this parasitic habit is injurious to other species there is no 
reason to doubt, but the extent of the injury has never been 
accurately determined. 
It was partly with the expectation of finding some points in the 
cowbird’s character to offset, to some extent, its parasitism that an 
investigation of its food habits was undertaken. The subject of its 
food has not attracted much attention from writers upon ornithology; 
for no great destruction of grain crops has been reported against the 
cowbird, nor has it ever been accused of preying appreciably upon fruit 
or garden produce. Dr. B. H. Warren, one of the few ornithologists 
to make a detailed examination of its food, says: 
The food of these birds consists of seeds, grains, berries and insects. Although 
Cowbirds subsist to a small extent on wheat and rye, they never, I think, * * * 
attack these cereals when growing. The seeds of clover, timothy, fox-tailed grass, 
bitter-weed, etc., are included in their bill of fare; blackberries, huckleberries, cedar 
berries, wild cherries and the summer grape (Vitis xstivalis, Mz.) are eaten. They 
subsist to a very great extent, however, on insects; large numbers of grasshoppers, 
beetles, grubs and ‘‘ worms’’ are eagerly devoured.” 
Maj. Bendire enumerates, as among the articles of cowbird diet, 
ragweed, smartweed, foxtail or pigeon grass, wild rice and the smaller 
species of grains, berries of different kinds, grasshoppers, beetles, 
ticks, flies, and other insects, worms, etc., and adds: ‘‘ Taking its food 
alone into consideration it does perhaps more good than harm.”* 
A collection of 544 stomachs has been received by the Biological 
Survey from twenty States ranging from Maine south to Virginia 
and west to Kansas and the Dakotas, and also from Tennessee, Georgia, 
Texas, Arizona, the District of Columbia, and Canada (see p. 73). 
Every month in the year is represented, though only three stomachs 
were taken in January. The total food found in these stomachs was 
dividedas follows: Animal matter, 22.3 percent; vegetable, 77.7 percent. 
The proportions in different months are shown by the accompanying 
diagram (fig. 3). Only a little more than 3 percent ef the stomach 
contents was sand or vravel—a very small amount when the large 
proportion of vegetable food is considered. The animal food consists “ © 
almost entirely of insects und spiders, a few snails forming the excep- 
tions. The insects comprise wasps and ants (Hymenoptera), bugs 
(Hemiptera), a few flies (Diptera), beetles (Coleoptera), grasshoppers 
(Orthoptera), and caterpillars (Lepidoptera). Wasps, ants, and flies, 
"Rept. U. 8. National Museum for 1893, p. 594, 1895. 
* Birds of Pennsylvania, revised ed., p. 210, 1890. 
i : Life Histories of N. A. Birds, II, Special Bul. No. 3, U.S. National Museum, p. 435, 
895. 
