PRACTICAL ENTOMOLOGY. 439 



THE FOOD RELATIONS OF BIRDS, FROGS, AND TOADS. 



THESIS FOR THE DEGREE OF MASTER OF SCIENCE. 

 BY CLARENCE M. WEED. 



I. The Food of Young Birds. 



Probably few subjects have been so much discussed with so little basis of 

 known facts as the ever important one of birds and their relations to agricult- 

 ure. Aside from a few occasional superficial examinations of the contents of 

 birds' stomachs but little has been done in investigating the food of adult 

 birds until the subject was attacked with the energy and scientific accuracy 

 characteristic of the present State Entomologist of Illinois, Professor S. A. 

 Forbes. 



The literature of the food of young birds is still more scanty. About the 

 only reference to the subject is that of Prof. Treadwell's earthworm-eating 

 young robin, which is as Prof. Forbes has said, "a bird whose fame has 

 extended over both hemispheres." 



It was witli a view of adding something more tangible to our knowledge of 

 the subject than the poetic sentiment which is so often thrown as a mantle of 

 charity over the actions of our feathered friends, that the investigations of 

 which this paper gives the preliminary results were undertaken. 



The method has been the same as that employed by Prof. Forbes in his 

 recent investigations of the food of the adult birds, namely an actual exam- 

 ination and determination of the contents of the young birds' stomachs. This 

 is the only accurate and scientific method of grappling with the problem, and 

 to it is due whatever value the results attained may possess. Some idea of the 

 diflficulty and magnitude of the task may be given by stating that a half day 

 was frequently spent in the examination of the contents of a single stomach. 

 After removing all recognizable insects and carefully estimating the percentage 

 of each to the whole of the food, a large proportion still remained to be picked 

 over, under the microscope, with a pair of needle points, the recognizable parti- 

 cles separated, the insects of which they were a part reconstructed in the mind's 

 eye, and the percentage estimated. Even after this a small portion usually 

 remained undetermined. The contents of each stomaclv were then bottled 

 and placed away for future reference and verification. 



I here desire to express my thanks to Prof. A. J. Cook, to whose patience 

 and knowledge I have been an hourly debtor; to Dr. W. J. Beal for the 

 identification of vegetable particles, and to Master Bertie Cook for many 

 specimens kindly procured. The published investigations of Prof. S. A. 

 Forbes have also been of great value, being, as they are, monuments of 

 scholarly and painstaking industry of which any man might well be proud. 

 From them I have obtained the forms for the tables which follow. 



