6 . 
Rabbit Manaqemen t 
M ol. 3, No. 4 
Page 6 
J. A. Bailey, R. J. Sig1 in 
The annual spring census of cottontail rabbits on the Allerton Park 4-H Area 
was conducted March 19, 1 966, with the help of students of the University of 
Illinois. The tails of 25 rabbits were dyed black during trapping operations in 
February and early March. In addition, some yellow-tailed animals -- from 33 
rabbits marked in October, l965 -- were present in the population. 
There were 210 observations of rabbits during the census: 98 of white-tailed 
animals, 27 of yellow-tailed animals, and 85 of black-tailed animals. Using these 
data, it is estimated with 95 percent confidence that 62 t 13 rabbits were present 
on the 120-acre 4-H Area during early March, I 966 . (Population estimate and 
confidence limits are based upon the Lincoln-Peterson index.) Ten years' data for 
the 4-H Area cottontail population are presented in Table 6 . 
In past years, estimates of winter mortality for this cottontail population 
have been based upon differences between October and spring population estimates. 
However, trapping during November and December, 1965 > indicated that many rabbits 
immigrated onto the 4-H Area during these months, coincident with a later-than- 
usual harvest of corn. Consequently, the only appropriate estimate of winter 
mortality for the I 965-66 season must be based upon survival of yellow-tailed 
rabbits marked during October. The census indicated that 13 percent (27 of 210) 
of the spring population of 62 rabbits had yellow tails. This indicates a survival 
of 8 out of 33 animals marked during October, producinq a mortality estimate of 
76 percent. 
Table 6. Estimates of cottontail rabbit abundance on the Allerton Park 4-H Area, 
1956-66. 
Year 
Spring Population 
Fall 
Popu1 at ion 
March 
Early October 
Early November 
1956 
— 
333 
— 
1957 
2$9 
— 
1958 
31 
324 
— 
1959 
132 
239 
— 
i960 
56 
309 
— 
1961 
161 
363 
— 
1962 
24 
'07 
— 
'963 
61 
— 
' 32 
1964 
58 
132 
101 
1965 
— 
99 
61 
1966 
62 
