310 



The track of my observers led them also through barnyards, 

 and gardens of vegetables and shrubs, and occasionally across a 

 shrubby ravine or a neglected field 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 classes of situation and kinds of food 

 available to them at the time, it is necessary to take into account the 

 areas in each of the crops along the line of travel. For this purpose 

 the following table has been prepared, showing the total distance 

 traveled through each kind of crop, and the acreage in each from 

 which a complete count and analysis of the bird life was obtained. 



Table III. Crop Areas, Indiana Line to Quincy. 



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

 seventy-two miles was traveled through 362 corn fields 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 cent, of the entire journey was 

 in fields of corn. The next largest area was in blue-grass pastures, 

 over which my observers traveled 51 miles, determining the birds 

 of 926.65 acres, which was 26.6 per cent, of the whole area of their 

 observations. Thirty-seven and four tenths miles in fields of stubble, 

 mainly oats, averaging 18.2 acres each, gave a total of 680.56 acres 

 for the 50-yard strip, or 19.5 per cent, of its entire length. Thus 



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

 form of a sufficient number is consequently 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. 



