Vol . 7, No. 11 
Page 6 
6. Rabbit Management J. A. Bailey 
Study of the population of cottontail rabbits on the Allerton Park Sanctuary 
has been discontinued. This population has been difficult and expensive to study 
and the population estimates obtained have lacked needed precision. Discontinuance 
of rabbit research on the Sanctuary makes it possible to concentrate our efforts 
on studying the population of cottontails on the nearby 4-H Area. 
The cottontail population on the 4-H Area is now being sampled by livetrapping 
for 10 days each month, using about 290 traps. A trapping period during September 
of this year initiated the program. During October, 48 of the captured rabbits 
were marked by dyeing their tails yellow with a picric acid solution (Lord 1963:58) 
During November, 35 of the rabbits were marked by dyeing their tails red with a 
solution of Calcofast Red and Calcozine Rhodamine B (American Cyanimid Company) in 
95 percent alcohol. The red dye tended to fade and was not entirely satisfactory. 
On November 21, a drive was conducted on the 4-H Area with the assistance of 
wildlife management students of the University of Illinois. There were 113 
observations of rabbits; 33 had white tails, 39 had red tails, and 41 had yellow 
tails. Population estimates applicable to early October and to early November can 
be calculated by considering the marked segments of the population separately. 
(See Monthly Wildlife Research Letter, April, 1964, for the method of calculation.) 
It is estimated with 95 percent confidence that there were 132 t 32 rabbits on the 
4-H Area in early October and 101 t 26 rabbits in early November. If the two 
marked segments of the population are combined, it can be estimated with 95 percent 
confidence that there were 117 — 14 rabbits on the 4-H Area in late October. The 
indicated mortality from early October to early November is 3' per 132 or 23 per¬ 
cent . 
When 9 years of data on the cottontail population of the 4-H Area are consid¬ 
ered (Table 5), it appears that this population crashed in 1962 and has never 
recovered. Fall population densities seem to have varied little during the past 
3 years, although our data indicate that this year's population of rabbits on the 
4-H Area is slightly smaller than last year's. 
Lord, Rexford D., Jr. 1963- The cottontail rabbit in Illinois. Illinois Dept. 
Conserv. Tech. Bull. 3- 94pp. 
Table 5- Estimates of cottontail rabbit abundance on the Allerton Park 4-H Area, 
1956-64. 
Spring Population Fall Population 
Year 
March 
Early October 
Early Novembe 
1956 
-- 
333 
-- 
1957 
47 
259 
1958 
31 
324 
-- 
1959 
132 
239 
-- 
I960 
56 
309 
-- 
1961 
161 
363 
-- 
1962 
24 
107 
-- 
1963 
61 
— 
1 32 
1964 
58 
1 32 
101 
