24 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 maxiroiiTd) and the meadowlark {Sturnella magna.f 

 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 prejang 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, thej'^ 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, huckleberrie-s, 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, smartwecd, foxtail or pigeon grass, wild rice and the smaller 

 species of grains, berries of different kinds, grasshoppers, beetles, 

 ticks, flics, 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 tlie 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). 

 Ever}' month in the year is represented, though only three stomachs 

 were taken in January. The total food found in these stomachs was 

 divided as 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 of the stomach 

 contents was sand or gravel — a very small amount when the large 

 proportion of vegetable food is considered. The animal food consists 

 almost entirely of insects and 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, 



' Kept. U. S. National Museum for 1893, p. 594, 1895. 

 '^ Birds of Pennsylvania, revised ed., p. 210, 1890. 



=• Life Histories of N. A. Birds, II, Special Bui. No. 3, U. S. National Museum, p. 435, 

 1895. 



