602 
(4) The «improvement period. This term serves to indicate the 
stage in which original prairie was drained and plowed, and wood- 
land cleared and plowed—or at least so thinned out and pastured as 
to be profoundly modified in character. The cultivated ground is 
supposed to be either pasturage or land under rotation of crops. 
This is the present stage of by far the greatest part of the county. 
(5) The market-garden stage. This term represents continuous 
and intense cultivation of limited areas of the land. 
(6) The village stage. This expression has reference to the 
stage of advancement in which houses are built separate from each 
other and considerable areas devoted to yards and gardens. 
(7) The city stage. This period is reached when the buildings 
touch each other, and there is practically no open ground for mam- 
malian life. 
Of course these various stages grade into each other, and in only 
a limited portion of the county here and there would there be 
simultaneous attainment to any of the later stages. Moreover, it is 
evident that the early stages must hold over an area considerably 
larger than a single county in order to be characterized by distine- 
tive mammalian life, while the later stages may prevail over pro- 
gressively smaller and smaller areas and still be so characterized. 
In the charts the lines represent the presence of the different 
animals, the varying size of each line indicating the relative abun- 
dance of that single species at different times, or during different 
stages of civilization. There is in the charts no comparison of one 
animal with another. A species is regarded as present so long as it 
seems certain that it bred within the county. Stragglers of deer 
and other large animals were seen much later than 1s indicated. 
The data used in making the charts were gotten in various ways. 
The reminiscences of early settlers as to variation in the abundance 
of the larger animals have been utilized, and though differing in de- 
tail they agree very well, on the whole, in regard to the most. im- 
portant general facts. The early records of travel through the state 
also furnished some data;and, lastly, the study of present distribution 
has thrown much light on the conditions favorable to each particular 
species. While the charts are not to be taken as exact mathematic- 
al representations of the variation in abundance of our mammals, 
either chronologically or with reference to the stages of civilization, 
it is believed that they may give a tolerably accurate idea of the 
