90 FOOD HABITS OF THE GROSBEAKS. 



are even less exclusively vegetarian than others of the family and 

 nearly half their food is animal. Moreover, the constituents of the 

 animal dietaries of the two groups differ considerably. Nearly all 

 finches hitherto examined have been found to avoid hairy caterpillars, 

 but the grosbeaks eat them eagerly. True bugs generally are neglected 

 by the smaller members of the sparrow tribe, while the grosbeaks con- 

 sume on an average 7.25 percent of these strongly flavored insects. 

 Further, while caged and hungry individuals of some of the smaller 

 sparrows refused both the Colorado and three-lined potato beetles, 

 cucumber and ladybird beetles, and also stinkbugs of the genus 

 Euschistus, each of these insects is captured in the open by one or 

 more, if not all, of the grosbeaks. In fact, the so-called protected 

 fireflies, leaf beetles, and ladybirds, as also hairy caterpillars and the 

 adaptively colored or distasteful bugs and scale insects, seem poorly 

 defended, for all of them serve as grist for the grosbeak mill. A dif- 

 ference between the vegetable dietaries of the grosbeaks and other 

 sparrows is also worthy of notice. Weed seeds form half of the an- 

 nual food of the latter group, while only one of the grosbeaks devours 

 so large a proportion, the others consuming an average of about 18 

 percent. 



To the grosbeaks in particular, as to the sparrow family as a whole, 

 general traits have been ascribed as characteristic which investigation 

 fails to substantiate. For instance, the grosbeaks are found to have 

 no special predilection for buds, notwithstanding popular opinion to 

 the contrary. Then, too, it is generally considered that the massive 

 grosbeak bill is especially designed to crack hard fruits and seeds, and 

 it would appear certain that in some way it is related to peculiarities 

 of food. Yet the smaller sparrows and the cowbirds, with much 

 weaker bills, break all sorts of seeds as readily as the cardinal. In- 

 deed, the food habits of the grosbeaks, as revealed by the present in- 

 vestigation, offer no clue to the origin of the form of bill. Its great 

 crushing capacity appears to be utilized only on rare occasions, one 

 cardinal, for instance, out of 500 eating a hickory nut. Practically 

 all the food eaten by grosbeaks seemingly could be manipulated just 

 as readily by birds with comparatively slender beaks. It is true that 

 the curiously curved beak of the parrot-bill may be useful in 

 securing the much relished seeds of bur grass (Cenchrus), but 

 the same kind of seeds is eaten also by the straight-beaked cardinal. 

 No doubt there is an intimate connection between the size and form 

 and the function of the grosbeak bill, but for the key apparently we 

 must look to past conditions of environment, for its extraordinary 

 size and shape appear to answer no present needs. 



Notwithstanding also the general similarity of bills, as well as of 

 other points of structure, the five grosbeaks differ considerably in food 

 habits. This divergence is beneficial to the birds, no doubt, when they 



