Economic Reasons for Protection 83 



his opinion until he is sure that no further evi- 

 dence will cause it to be reversed. 



When Mr. F. E. L. Beal states that fifty-- 

 three per cent, of the rusty blackbird's food con- 

 sists of animal food, chiefly noxious insects, he is 

 not guessing either. He shows you a table which 

 he has prepared after the careful examination 

 of the stomachs of many blackbirds. There you 

 can see at a glance what kinds of food and the 

 proportions of each, which the birds eat during 

 every season of the year. And you can see also 

 that bad deeds are recorded as carefully as good 

 ones, and that when practically nothing but grain 

 is eaten, the table shows it. 



And when Dr. Sylvester D. Judd expresses 

 an opinion on the food of sparrows, he has based 

 that opinion on the contents of the stomachs of 

 between four thousand and five thousand spar- 

 rows; and so if he tells us, as he does, that dur- 

 ing the colder half of the year, the seeds of smart 

 weed, bird weed, pigeon grass, pig weed, lamb's 

 quarters, ragweed, crab grass, and other seeds, 

 form four-fifths of the food of song sparrows, 

 we may accept the statement as a fact. 



Of course I am aware that the subject of the 

 economic value of birds, when taken up in detail, 

 is very complex, and that the questions involved 

 are not always easy to answer. Some birds, like 



