38 TRANSACTIONS OP THE ILLINOIS 



That we are not yet prepared for intelligent action of this kind, is evident 

 to all. That we should encourage the breeding of some birds, I think all 

 are ready to admit. That there are some others which it would be to our 

 advantage to destroy, is very commonly believed. But as soon as we ask, 

 " what species will you preserve and what destroy, and how complete a 

 basis in fact has your preference or your condemnation?" we encounter, 

 at once, a radical conflict of views and a mass of conjecture, careless 

 observations, crude and inconclusive reasoning, and much prejudice, and 

 much more guess work. Even in the East, where this question has been 

 prominent much longer than here, little is known that is accurate and 

 exhaustive about the food of any except the commonest species, and 

 the assertions made often rest upon data which no scientific man would 

 accept as sufficient. And even if the subject had been worked out else- 

 where with all possible skill and completeness, it would be necessary to 

 know to what extent the food of a species varied with its locality, climate, 

 etc., before we could adopt such conclusions for our own guidance. In 

 fact, we should, even in that event, need to make a careful, original study 

 for our own State. The magnitude and difficulty of the subject will be 

 more apparent when I have made a more explicit statement of the condi- 

 tion of the problem. 



We need to know the food of the commonest birds, at all seasons of 

 the year and in the most varied surroundings. A bird which may do con- 

 spicuous injury at some seasons, may quietly and unsuspectedly do a far 

 greater good at others. One which in prairies, not finding there its 

 favorite food in abundance, may be reduced to feed on the products of 

 the garden, may be in other situations either entirely harmless, or so 

 beneficial as to make its wholesale slaughter a public injury. The food of 

 birds may further differ, materially, with different years, for all that we at 

 present know to the contrary. 



We must also know the food of each species at different ages of the 

 individual, especially of birds while yet in the nest, as well as of adults. 

 Many of the seed-eaters, for example, feed their young almost entirely 

 upon insects ; and it is evident that facts of this kind are of great import- 

 ance for our purpose. 



But the food of nearly every kind of bird, having any direct relation 

 to our subject, is mixed, partly injurious and partly beneficial. Even the 

 bluebird feeds upon predaceous beetles as well as the injurious ones, and 

 takes an occasional hymenopter also. We shall find it necessary, there- 

 fore, to learn the proportions in which the different elements of the bird's 

 food enter into the total amount. We must attempt quantitative as well 

 as qualitative investigation. In short, we must open an account current 

 with every common species, at least, and from time to time strike a bal- 

 ance, until we are sure that we have the items for a fair average of its 

 services and their cost. Then, and not until then, we shall be ready to 

 act intelligently. Without such knowledge our conclusions will be too 

 much like the verdict of a sleepy jury, which should catch only here and 

 there a sentence of the evidence. Further, to exhaust the possibilities of 

 important discovery, it would be necessary to study the food-habits of the 



