82 BULLETIN No. 36 



species together, is perhaps unfortunate. The Food of U^cst- 

 ling Birds, p. 411-436, by Sylvester D. Judd, Ph. D.,goes into 

 the subject pretty thoroughly, it is surprising what a large 

 amount of valuable information the writer has placed in order. 

 A number of diagrams illustrating the proportion of food of both 

 nestling and adult of many of our common birds show the com- 

 parative value at a glance, >vhere a mere statement of percent- 

 age would fail nine times out of ten. Several plates from plio- 

 tographs taken of young in nest also appear. In conclusion he 

 says: "It will be observed that whatever the character of the 

 food of the adult bird, the young, excepting those of Doves and 

 Pigeons, are at first fed on animal diet, and that this dJLt is 

 gradually changed, where change is necessary, to conform to 

 that of the mature bird. This is probably due to the fact that 

 animal food has a higher nutritive value and is more easily 

 digested than the available vegetable food. As nestlings in- 

 crease in weight from one-fifth to one-half daily, and at certain 

 stages of growth require dajly more than their own weight in 

 insects, it is essential that their food should be readily obtain- 

 able. Spiders, grasshoppers, caterpillars and crickets answer 

 these requirements very well and are a favorite nestling food 

 with many of passerine or perching birds. Birds that are largely 

 vegetarian mingle fruit or grain in constantly increasing quan- 

 tities with the insects fed to their young, though insects usually 

 remain the chief component of the food until maturally is nearly 

 reached. But these birds generally substitute such insects as 

 hard beetles, carabids, dung-beetles, may-beetles and weevils 

 for the softer food of other perching birds. The caterpillars 

 selected are generally such hairless kinds as canker worms, 

 cutworms, and army worms, all of which are serious pests. 

 But hairy caterpillars are eaten to a certain extent." F. L. B. 



