1^4 ^i\^T>-E.KSoi<i, Food of Niiihatchcs and Chickadees. \ a^x\\ 



several occasions hooked 0. 7)ieJania\\\i\\ a small hook baited with 

 a piece of seal blubber, but as a rule they decline to be taken in 

 by any such means. Both O. melajiia and O. socorroeiisis will at 

 times dive a foot or more below the surface for a piece of meat 

 that is sinking if they are hungry, but diving seems to be out of 

 their usual line of business and is only resorted to when food is 

 scarce. They seem to be unable to get below the surface of the 

 water without first rising two or three feet and plunging or drop- 

 ping, exactly as I have seen the Black-footed and Short-tailed 

 Albatrosses dive under similar circumstances. 



THE ECONOMIC VALUE OF THE WHITE-BELLIED 

 NUTHATCH AND BLACK-CAPPED CHICKADEE.^ 



BY E. DWIGHT SANDERSON. 



The value of our common birds as insect-destroyers has 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 (^Pariis atricapilhis 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 



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



