SPECIES. 



95 



Marshall Hall, is frequently shot, and its valuable work as a destroyer 

 of weed seed and insects is thus often cut oj5*. 



When the bobolink {DolicJionyx oryzivorus^ fig. 35) tarries on the 

 farm in its southward mig-ration it lives wholly on the wild rice of the 

 calamus swamp, but on its return journe}^ in May it eats injurious 

 insects and weed seed of the wheat and clover fields. Six stomachs 

 were collected in May. 



The cowbird {Molotlwics ater)^ as has been shown by Prof. F. E. L. 

 Beal,^ takes three times the volume of seeds that it takes of insects. 

 Both of the 2 stomachs examined contained grasshoppers {Xiphidiwn 

 and Melanoplus) and 1 of them leaf -hoppers, two elements character- 



FiG. 35.— Bobolink. 



istic of the insect food of the species. The bird does little damage 

 to grain fields, and renders much service with other birds in reducing 

 the weed-seed harvest of the farm. 



BLACKBIRDS AND ORIOLES. 



The red- winged blackbird {Agelaius plimniceus^ fig. 36), however 

 destructive to grain it may be elsewhere, does no damage in the grain- 

 fields at Marshall Hall. Its insect food, which is to its vegetable food 

 as one to three, is composed largel}^ of weevils, caterpillars, and grass- 



« Bobolink, Blackbirds, and Grackles. 

 Agriculture, p. 29, 1900. 



Bull. No. 13, Biological Survey, Dept. of 



