48 FOOD OF BOBOLINK, BLACKBIRDS, AND GRACKLES. 



whole food, but from its distribution through the year does not 

 appear to have been taken from the harvest fields. It is probable 

 that some of it was gathered from newly sown fields, but the greater 

 part was undoubtedly stolen from corncribs or picked up in roads and 

 stock yards as waste grain. 



Weed seed is not so important an item of food with the rusty black- 

 birds as it is with the redwings, since with the former it amounts to 

 only 6 percent of the year's food, and contrarj^^ to observations on 

 most seed-eating birds, the greater portion of it is apparenth^ eaten 

 in the insect season. Only 1 percent was found in the stomach taken 

 in January, but the amount increases irregularlv up to a maximimi 

 of 23.3 percent in May. Of June and July we know nothing, but 

 in August, the month in which the redwing begins to increase its 

 seed diet, there is not a single trace of weed seed in the food of the 

 rusty blackbirds. It constitutes 6.6 percent in September, a trifle in 

 October, and 15 percent in November and is entirelj^ absent in the 3 

 stomachs taken in December. This erratic distribution evidently indi- 

 cates that weed seed is not sought after, but is simply taken when 

 nothing better is at hand. Miscellaneous items of vegetal^le food 

 amount to 16.6 percent of the food of the year. Fruit was found in a 

 few stomachs, but does not appear to any important extent. Only 

 three kinds were determined, but several stomachs contained pulp or 

 skin that could not be identified. Several buffalo berries {Shepherdia 

 argmtea) were found in one stomach, hackberries {Celtis occldentalis) 

 in another, and seeds of blackberries or raspberries {Ruhm) in two or 

 three others. Mast was found in a few stomachs, but the greater part 

 of the miscellaneous food was indeterminable. The birds are evi- 

 dently great scavengers, and so gather much food that is scarcely sus- 

 ceptible of classification. 



SUMMARY. 



While this record of the food of the rusty lilackbird is somewhat 

 fragmentary it still gives a very good idea of the bird's general diet. 

 One important conclusion that can be drawn is that animal food is 

 preferred, vegetable food serving as a makeshift. It is nearly certain 

 that in June and July, when the birds are engaged in the exhausting 

 function of reproduction, the diet must be almost exclusively animal. 

 If those months were represented in this investigation, the relative 

 proportion of the two classes of food would be much changed, and 

 animal food would take a higher rank. The vegetable food is of little 

 conse(iuence, as the ])irds show no decided predilection for any partic- 

 ular kind, but eat whatever is at hand when animal food can not be 

 o1)tained. Grain is not eaten to any great extent at harves.t time, and 

 the other items do not seem to have any special relation to the season 

 in which they are eaten. While considerable animal food beside 

 insects is eaten, on the other hand a consideral)lc (juantity of harmful 



