218 Game Survey of the North Central States 



years ago are now heavily infested with red foxes, without any known change in 

 their visible condition to account for the change in fox abundance. 



3. The tendency for reds to replace grays has been reversed (that is, grays 

 have replaced reds) in three knoivn instances, without any change in the visible 

 condition of the country. In one of these instances reds have subsequently re- 

 placed grays for the second time. 



4. The original shift from grays to reds shows a remarkably uniform date 

 over large areas more uniform than the progress of settlement would seem to 

 account for. 



5. The present distribution of grays, while conforming roughly to country 

 containing rock ledges, exhibits unaccountable exceptions, where grays are absent 

 from country seemingly identical with other nearby localities in which they are 

 not only present, but predominate. 



These findings suggest that while the recognized factors of type, settlement, 

 and hunting undoubtedly influence the kind and number of foxes, that other 

 invisible factors, as yet unknown, are also at work, and may be even more potent 

 than those ordinarily recognized. The discovery of these invisible factors is im- 

 portant, both from the viewpoint of fox-control as a predator, and fox-conserva- 

 tion as a game animal. 



The evidence on which these five indications are based will now be set forth. 



History of Red: Gray Ratio. Scattering information on the fox ratio 

 was obtained in various States, but a special study of it was made in Missouri. 

 Map 18 gives the present red: gray ratio by counties in so far as this was de- 

 termined by inquiry among competent persons during the survey. The map also 

 shows the date of first appearance of reds, and the date of last appearance of 

 grays. The map is of course far from complete, even for Missouri. 



The present distribution of reds in Missouri appears to be practically State- 

 wide, with the notable exception that few or no foxes of any kind occur in Bates 

 and Vernon Counties, which lie in the prairies of the Kansas border. This "fox- 

 less area" can hardly represent an aversion to prairies as such, because Audrain 

 County, in northeast Missouri, which is quite as flat and bare as Bates or Vernon, 

 has quite a few foxes of both species, the reds evidently inhabiting the prairie, 

 and the grays the riverbreaks. Another reason for doubting whether the red fox 

 is averse to inhabiting prairie as such is that it has recently become quite abundant 

 on the Illinois prairie near Freeport, and it has recently invaded the marshy 

 prairies of Sandusky County, Ohio, and of the upper Kankakee in Indiana. These 

 invasions will be described in detail later. 



The original distribution of the red fox in Missouri is unknown, but it was 

 evidently much more restricted than at present. Table 49, to be presented later, 

 shows six widely scattered counties which had no red foxes until the end of the 

 last century. (As to the reliability of this information, it is my experience that 

 fox hunters retain a very clear recollection of former conditions. By compiling 

 more information from them, the original distribution of reds could easily be 

 determined.) 



