38 



(which has since been drained), but some of the higher ground, 

 formed by the undulation of the surface and surrounded by the black 

 soil, is lighter in color and is well drained. Thus in the black soil areas 

 there are both wet and well-drained tracts, and corresponding differ- 

 ences in the habitats. 



The originally wooded and the present wooded areas east of 

 Charleston, in the vicinity of the Embarras River, are in a region quite 

 different from the prairie both in topography and in soil. Here the re- 

 lief is much more pronounced, on account of both the proximity of the 

 river and the greater development of the drainage lines, which have cut 

 a few hundred feet below the general level of the country. The tribu- 

 tary valleys and ravines are numerous and steep-sided, and in general 

 are wooded, the density varying with the amount of clearing done. 

 Most of the soil of the wooded areas and along the bluffs is distinctly 

 lighter in color than that of the black soil prairie, and is presumably 

 "gray silt loam" (Hopkins and Pettit, '08 : 238-242), though along the 

 flood-plain and the river bottom the soils are mixed in character. 



II. The Ecological Stations 



In the study of an area or an animal association of any considera- 

 ble size two methods are available. One is to examine as much of the 

 area as is possible and secure data from a very wide range of condi- 

 tions. This method is useful in obtaining the general or broad features 

 of a region or an association, though to a corresponding degree it must 

 ignore local influences and details, and by it most of the previous stud- 

 ies upon prairie animals have been made. It seemed, therefore, that in 

 the present study a somewhat more intensive method was desirable, 

 particularly in view of the fact that the extinction of prairie and for- 

 est is rapidly progressing. The method followed was to examine a 

 large area in order to select a representative sample, and upon the 

 basis of this sample to make as intensive a study as time and circum- 

 stances would permit. This method has the advant.ige of making it 

 possible to preserve at least some record of the local details; and at the 

 same time, to the degree that the selected area is a true sample, it also 

 gives the results a much wider application. 



The prairie samples examined were all along the rights-of-way. 

 and the forest was a second-growth woods on the bottoms and bluff' 

 of the Embarras River, on a farm belonging, at that time, to Mr. J. I. 

 Bates. Practically all of the observations here reported upon were 

 made during August, 19 10. The forest is a modified one, but it ap- 

 pears to have been cut over so gradually that its continuity as a forest 

 habitat was not completely interrupted, although the cutting has prob- 



