50 FOOD OF BOBOLINK, BLACKBIEDS, AND GEACKLES. 



BREWER'S BliACKBIRD. 



{Scolecophagus cyanocephalus. ) 



Brewer's blackbird breeds from Manitoba and the eastern edge of 

 the Great Plains south to northern New Mexico and westward to the 

 Pacific, and spends the winter in the southern part of this region and 

 in Mexico. The economic status of the species has as yet hardly 

 become well defined, but some complaints have been received from the 

 grain-growing sections, and it ma}^ possibly be a pest where it exists 

 in any great numbers. The bird is eminently gregarious most of the 

 year, though less so at breeding time. Like the cowbird, it is an 

 industrious gleaner in pastures, barnyai'ds, and roads, and even invades 

 the streets of towns for the purpose of gathering scattered grain and 

 other forage. 



But little testimony is avaihible as to the food of Brewer's blackbird, 

 but Goss says that the memliers ^ this species are "social, gregarious 

 birds, ])reeding in small colonies, and foraging together over the culti- 

 vated fields, pastures and plains; indiscriminate eaters of insect life, 

 seeds, etc., and " * '^ regular visitants of the slaughterhouses."^ 

 In the investigation In^ the Biological Survey 146 stomachs were 

 examined, collected from six States and representing every month 

 except April (see p. 75).^ The first analysis of the food shows that 

 animal matter forms 31.8 percent and vegetable matter 68.2 percent. 

 The animal food consists almost wholly of insects, the oul}'^ exceptions 

 being a few spiders and snails. The insects are mostly beetles, ants, 

 wasps, and grasshoppers, with a few caterpillars, flies, and bugs. 

 Beetles amount to 7.8 percent of the food of the year. The only 

 group which appears at all prominently is that of the snout-beetles, or 

 Rhynchophoi-a, Avhicli in ]\Iay constitute 2J> percent of the food. In the 

 other months they are not found so often, and the average for the year 

 is only 3.4 percent. Predaceous beetles (Cara])ida>) are eaten to the 

 amount of 1.7 percent, and are not conspicuous in any month. 

 I lymenoptera constitute 14.8 percent of the food for August, ])ut do 

 not appear verv prominently in the other months, and average but 2.5 

 percent for the year. They consist for the most part of wasps and 

 ants, with a few of the smaller parasitic species. 



Grasshoppers are the favorite insect diet, constituting more than 

 half of the total animal food (16.1 percent). Onlj^ a trace appears in 

 the February stomachs, but in March the amount increases to 20.5 

 percent, and except in July does not fall below this figure until Octo- 

 ber. In August, which as usual is the month of greatest consump- 

 tion, grasshoppers constitute 47.5 percent — nearly half of all the food. 



*Hi8t. Birds of Kansas, p. 409, 1891. 



'One stomai-h was taken in April, l)ut as its contents were quite unlike the average 

 of those collected in March and May, it has l)een discarded until more can be 

 obtained for the same month. 



