Auk, XV. April, 1898. p^. l'^^'">~^~'^ 

 TB.Y. ECONOMIC VALUE OF THE WHITE-BELLIED 

 NUTHATCH AND BLACK-CAPPED CHICKADEE.i 



BY E. DWIGHT SANDERSON. 



The value of our common birds as insect-destroyers lias of 

 late years come to be recognized as an important field of inves- 

 tigation for the ornithologist and a large item in rural economy. 

 Much valuable work has been done in determining their economic 

 relations, but there has also been a large amount of assumption 

 by various writers based on insufficient data. It is my purpose 

 in this thesis to determine the character and amount of food and 

 the economic relations of two of our most common residents, the 

 White-bellied Nuthatch [Sitta carolinensis Lath.) and the Black- 

 capped Chickadee (^Parus atricapillus Linn.) from the analysis of 

 the stomachs of 34 specimens of the former, and 28 of the latter, 

 notes taken while collecting them, and incidentally from as much 

 reliable data as could be found elsewhere. 



METHOD OF ANALYSIS. 



In no instance was any food found in the true stomach, mouth, 

 or gullet, and the only part containing food was that ordinarily 



1 A Thesis submitted to the Faculty of the Michigan Agricultural College. 



ground much ot the time ; while the last eleven were secured 

 daring the spring (April 10-17), before the foliage was out. The 

 contents were tabulated and two totals made, showing the differ_ 

 ence in seasons. I had wished to secure specimens during the 



