Vol. 5, No. 11 
Page 3 
As anticipated, the rabbit populations on both the 4-H and Sanctuary areas were well 
below those of 1961. In fact, these two areas had the lowest fall populations since 
the study was initiated in 1957. The population estimate for the 4-H area, with 
95 percent confidence limits, was 107 + 24 cottontails. Since the study area covers 
160 acres, the mean density was estimated to be 0.67 + .15 rabbits per acre. There 
were 71 + 19 rabbits estimated to be present on the 100 acre Sanctuary area. On 
this area mean density was 0.71 + .19 cottontails per acre. Data on spring and 
fall cottontail abundance for the two study areas during the 6 years of the study 
are given in Table 3. 
Table 3. Summary of cottontail populations on Allerton Park study areas, 1956- 
1962, as determined by color marking and drive censuses. 
1956 
1957 
1958 
1959 
1960 
1961 
1962 
Sanctuary Area 
Spring 
No Data 
60 
42 
64 
54 
128 
Fall 
238 
120 
171 
125 
141 
71 
Harvest 
•"* 
*>C 
42 
"ir 
In Progress 
4-H Area 
Spring 
No Data 
47 
31 
132 
56 
161 
24 
Fall 
333 
259 
324 
239 
309 
363 
107 
Harvest 
113 
92 
109 
95 
SL 
167 
Closed 
Area rabbit population not subjected to controlled harvest. 
If considered separately, data for the 4-H area might suggest a mortality de¬ 
pendent population control. However, as similar declines in rabbit abundance are 
apparent in the data from both areas, and since the 1962 spring cottontail population 
on the Sanctuary area was high, it is logical to assume that some factor other 
than hunting was responsible for the low rabbit densities on the area in 1962. 
Collection of eye lenses from hunter-killed rabbits began in late November on 
the Sibley, Neoga, and Bogota study areas. A sample of at least 100 lenses will 
be obtained, if possible, from each area so that sufficient information on cotton¬ 
tail age composition in 1962 will be available for population analysis. 
Controlled harvest of the cottontail population on the Sanctuary area was 
initiated November 17. This year a land unit of approximately 230 acres will be 
subjected to harvest treatment. Rabbit removal sufficient to achieve a 50 percent 
harvest of the estimated fall population and an 80-85 percent fall-to-spring re¬ 
duction is planned. Trap removal of cottontails will supplement hunting. 
5. Responses of Bobwnites and Prairie Chickens to Habitat Manipulation 
J. A. Ellis, R. J. Ellis 
Attempts were made during October and November to locate each prairie chicken 
flock in southern Illinois. High school vocational agriculture instructors in 
