311 



The track of my observers led them also through barn- 

 yards, and gardens of vegetables and shrubs, and occasionally 

 across a shrubliy ravine or a neglected Held which had grown 

 up to weeds With the exception of a large marshy tract in 

 the bottoms of the Illinois River near Meredosia, there was very 

 little waste land worth mentioning on this line. 



For an analysis of the preferences of the principal species 

 of birds with respect to the various clas.ses of situation and 

 kinds of food available to them at the time, it is necessary to 

 take into account the areas in each of tlie crops along the line 

 of travel. For this purpose the following table has been pre- 

 pared, showing the total distance traveled through each kind 

 of crop, and the acreage in each from which a complete count 

 and analysis of the l)ird life was obtained. 



TABLE III. CROP AREAS, INDIANA LINE TO QOINCY. 



Corn, it will be seen, was the principal crop. A distance 

 of nearly seventy-two miles was traveled through 362 corn 

 Helds of an average size of 32 acres per field, and all the birds 

 were determined for 1306.64 acres of this crop. That is, 38 per 



*Virtually all central Illinois farm-fields are rectangular, and the average form 

 of a siiftioient nmiiber is conseciuently that of a square. The length of one side of 

 such an average field was found by dividing the entire distance traveled in any crop 

 by the number of fields of that crop crossed. The .square of this side is, of course, 

 the area of this average field. 



