Rabbits 95 



(1) Cottontails were sick in most of the north central States during the last 

 cyclic depression. 



(2) Mortality from the sickness was confined to small spots in the South, 

 but became uniform and widespread toward the north edge of the range. 



(3) Cottontail shortages in the cornbelt usually last only one year but 

 sometimes up to four years. They average distinctly shorter than the cyclic de- 

 pressions in snowshoes and grouse. 



(4) Shortages of apparently similar nature, duration, and distribution have 

 occurred in years past. A severe one of four years duration occurred in Logan 

 County, Illinois, in 1870. Whether these former shortages always coincided with 

 grouse cycles is not determinable from this study. 



Holing-up Zone. In Wisconsin cottontails invariably hole up during 

 severe winter weather. On a really cold day it is possible to hunt all day in 

 good rabbit country with a good dog without rinding more than one or two 

 rabbits bedded out where they can be jumped and seen. During warmer weather 

 several dozen might be jumped during the same hunt on the same ground. Wis- 

 consin cottontails also tend to hole up when hunted hard, or after winter rains. 



In Missouri, however, the normal number of cottontails can be found bedded 

 out even during the coldest weather. There is evidently a difference between 

 the daytime behavior in the northern and southern parts of the north central 

 region. 



That this difference is not merely a matter of temperature is indicated by the 

 testimony of at least two observers who say that rabbits bed out in northwestern 

 Iowa and southeastern South Dakota in 10F., whereas +10F. will put them 

 all in their holes at Madison, Wisconsin. 



The evidence gathered during the survey indicates that the line of demarca- 

 tion, or "holing-up line," is more distinct and more uniform from year to year 

 than one would expect. The localities where definite evidence was found that 

 cottontails hole up are marked "H" on the map. The localities where they bed 

 out are marked "BO" on the map. The heavy dashed line marks the approximate 

 boundary of the holing-up zone as indicated by the evidence. 



This phenomenon is of some importance to management. In cottontails, as 

 in quail, winter is the critical season for cover. A rabbit population which can 

 get through the winter by substituting holes for surface cover should be more 

 resistant, other factors being equal, than one which cannot. It should also be 

 harder to over-kill. 



South of the holing-up line cottontails bed out in standing corn and, seem 

 to prefer it as a place for bedding out. North of the holing-up line cottontails 

 seldom bed out in corn, even in mild weather, although they of course feed in 

 cornfields there as elsewhere. 



The Trempealeau "Irruption." Omar Emmel, of Blair, Trempealeau 

 County, Wisconsin, reports seeing vast numbers of white rabbits, which he in- 

 sists were snowshoes, between Blair and Whitehall 53 or 54 years ago, or about 



