60 FOOD OF BOBOLINK, BLACKBIRDS, AND GEACKLES. 



Nearly 2,500 crow blackbird stomachs have been examined in the 

 laboratory of the Biological Survey, of which 2,346 contained food; 

 the remainder were empty. These stomachs were obtained from 

 twenty-seven States, the District of Columbia, and Canada (see p. T5). 

 Nebraska and Dakota are the most western States in which any were col- 

 lected, and Florida and Texas the most southern. The stomachs were 

 taken during ever}-^ month in the j^ear, but as the great hodj of the 

 birds leaves the Northern States in October and does not return until 

 March, but few stomachs could be procured in November, December, 

 January, and February. Great pains were taken to secure a large 

 number during the breeding months of May and June, with the result 

 that a little more than half of the whole collection was obtained at 

 this time. Observation has shown that the food of 3^oung birds often 

 differs materialh' from that of the adults, and in order to test this 

 point 4.5G nestlings were collected in May and June. 



The food of the whole year, taking into account all the 2,346 stom- 

 achs, young and adult, comprised 30.3 percent animal, and 69.7 per- 

 cent vegetable matter. The animal food was found to be composed of 

 insects, spiders, myriapods, craylish, earthworms, sowbugs, hair snakes, 

 snails, tish, tree toads, salamanders (newts), lizards, snakes, birds' eggs, 

 and mice. 



Insect food constitutes 27 per cent of the entire food for the year, 

 and is the most interesting part of the bird's diet from an economic 

 point of view. 



When it is examined month b^- mouth, the smallest quantity appears 

 in February (less than 3 per cent of the whole food), but as onl}' 8 

 stomachs were taken in this month the result can not be considered 

 very relia]>le. In March it rises to one-sixth, and steadilv increases 

 till May, when it reaches its maximum of five-eighths of the whole; it 

 then decreases to one-sixth in October, and appears to rise again in 

 Novem])er, but the number of stomachs tnkeii in that month is too 

 small to warrant any general conclusions. The great number of insects 

 eaten in May and June is due in part to the fact that the young are fed 

 largely on this kind of food. 



Analysis of the insi'ct food presents many points of interest. Among 

 the mo,st important families of beetles arc the scarabjuids, of which the 

 common June bug or ]SIay-beetle and the rose bug are familiar exam- 

 ples. These insects are eaten, either as beetles or grubs, in every 

 month except January and November; in May they constitute more 

 than one-fifth, and in June one-seventh of the entire food. The habit 

 grackles have of following the plow to gather grubs is a matter of 

 common observation which has been fully confirmed by stomach exam- 

 inations. Many stomachs were found literally cranmied with grubs, 

 and in many more, where other food predominated, the hard jaws 

 showed that grubs had formed a goodly portion of a previous meal. 



