BOBOLINK 39 



but it is probable that (as in other species) the yellow edgings diminish 

 with age." 



The fact that certain male bobolinks in captivity have assumed the 

 black spring plumage without any apparent signs of molting has led 

 to some discussion of the old, threadbare theory of color change with- 

 out molt. Dwight (1900, p. 123) has discussed fully this and the evi- 

 dence offered by others, and concludes that there is not the slightest 

 evidence to support the theory. "Nowhere among living organisms 

 do restorative changes in tissue take place without destruction or 

 casting off of the old. Consequently belief that a feather which regu- 

 larly develops, dies and is cast off, can possibly violate such a universal 

 law is not only contrary to common sense but contrary as well to every 

 established fact regarding the moulting of birds." 



The sequence of molts and plumages of the female is apparently 

 similar to that of the male, but not so conspicuous. 



Food. — As we know the pretty bobolink on its northern breeding 

 grounds we can find little to complain of in its feeding habits, which 

 are mainly beneficial to our interests, or at their worst only neutral, 

 but when it becomes the "rice bird" in the Southern States the planters 

 have a strong case against it. While with us in the north it feeds on 

 insects and the seeds of useless plants, and the young are fed almost 

 exclusively on insects, mostly harmful species. After the young are 

 on the wing, the flocks wander about, living mainly on weed seeds, a 

 little waste grain, and the seeds of the wild rice which grows along 

 the borders of our streams and marshes. 



Of the 291 stomachs examined by Beal (1900), 231 were collected 

 in the Northern States from May to September, inclusive. The food 

 was found to consist of 57.1 percent animal matter and 42.9 percent 

 vegetable. His table lists the following average percentages for the 

 five months: Predaceous beetles 0.6; May-beetle family 2.7; snout- 

 beetles 9.0; other beetles 6.7; wasps, ants, etc., 7.6; caterpillars 13.0; 

 grasshoppers 11.5; other insects 4.6; spiders and myriapods 1.4; oats 

 8.3; other grain 4.1; weed seeds 16.2; and other vegetable food 14.3 

 percent. Aside from the trace of useful predaceous beetles and a few 

 parasitic Hymenoptera, all the other insects are more or less harmful; 

 the large percentages of caterpillars and grasshoppers may be placed 

 to the credit of the bobolink. The small amount of grain eaten is of 

 little account when compared with the large amount of noxious weed 

 seeds such as barn-grass, panic-grass, smartweed, and ragweed. 



Beal evidently found no corn in the stomachs he examined, but 

 Warren (1890) says that, in Pennsylvania, "they visit the cornfields, 

 and in company with the English Sparrow, prey to a more or less 

 extent on the corn; like the sparrow they tear open the tops of the 

 husk and eat the milky grain." 



380928—57 1 



