Vol . 8, No. 1 
Page 4 
the 5 percent level of probability, thus supporting the concept that the number of 
cocks on booming grounds is dependent on the amount of undisturbed grassland in the 
vicinity. As the number of cocks on booming grounds is a good indicator of popu¬ 
lation size, the significance of the test applies to the population as well as to 
the cocks. 
Figure 1. Relationship between number of male prairie chickens counted on booming 
grounds in 1364 and percent of area in grass meadows and idle fields of grass on 
10 census areas during the summer of 1963* 
6. R abbit Management j. A . Bailey 
Data obtained from the annual fall census and from capture records of cotton¬ 
tail rabbits on the Allerton Park 4-H Area have indicated that considerable natural 
mortality occurs in this rabbit population during the 7 weeks immediately preceding 
the hunting season. The fall census indicated a mortality of 23 percent from 
October 5 to November 5 (Monthly Wildlife Research Letter, November, 1964). A second 
method for calculating mortality (Lord 1959) likewise indicated a mortality of 23 
percent during this period. 
