VALUE OF BIRDS TO MAN. 59 



the economic ornithologist, lead him to accept as facts the 

 extreme statements made by competent investigators. 



It will be seen from the foregoing explanations that, while 

 a large number of injurious insects found in a bird's stom- 

 ach may indicate its usefulness, it may not always mean that 

 it has eaten a great bulk or quantity of such food. 



The question which most interests the farmer, however, 

 is, not so much what birds require to sustain life, as how 

 much they will eat if they can get their fill. If in times of 

 plenty birds will eat more than they really need, then they 

 become more useful or injurious, as the case may be, than 

 they would be if they ate only enough to live. The amount 

 of food that has been found in birds' gizzards indicates that 

 they will eat until surfeited. 



Professor Beal, who has examined the contents of over 

 twenty thousand stomachs, says, regarding this habit : 



The majority of people have no idea of how much these insects can 

 be compressed in the stomach of a bird. It is often the case that when 

 a stomach has been opened, and the contents placed in a pile, the heap 

 is two or three times as large as the original stomach with the food all 

 in it. Moreover, in the cases where remarkable numbers of insects 

 have been found, the crops or gullets usually have been full, as well as 

 the stomach itself. It is a fact, perhaps not generally known, that with 

 birds that have no special enlargement of the gullet in the nature of a 

 crop, the whole gullet is used for the purpose ; and when favorite food 

 is abundant, the bird will fill itself to the throat. I have seen a Snow- 

 bird so full of seeds that they were plainly in sight when the beak was 

 opened, and from the bill to the stomach was a solid mass of seed. 

 The stomachs of birds are often packed so hard and tight with food 

 that it is a wonder how the process of digestion can go on ; but it does, 

 nevertheless. 



In giving the maximum amounts of food found in birds' 

 stomachs, I shall be obliged to refer to the publications of 

 the Bureau of Biological Survey of the United States De- 

 partment of Agriculture ; and it is but just to say here 

 that the world owes much to Dr. Merriam, chief of the 

 Bureau, for his indefatigable labors in behalf of science and 

 agriculture. 



In connection with the work of the survey, the contents 

 of more than thirty-five thousand bird stomachs have been 



