Vol. 14, No. 4 
Page 4 
Mark sanctuaries. They were 75 percent higher on the Yeatter Sanctuary and 
63 percent higher on the Donnelley Sanctuary. The count of cocks (seven) 
remained about the same on the C. McCormick Sanctuary, but the number of 
hens (up to 25 ) seen on the booming ground this spring was at least three 
times higher than in 1970. The J. V/oods ground (on private land) lost 
approximately 24 cocks since last spring but still held about 30 cocks 
through this spring. The only discouraging note regarding the dispersion 
of prairie chickens at Bogota this spring was the lack of booming cocks on 
or near the 80-acre J. McCormack Sanctuary, which is located on the southern 
edge of the study area. 
6. Rabbit Management G. B. Rose 
During the fall trapping on the 4-H Camp area at Robert Allerton Park 
in 1970 , lengths and weights of captured cottontail rabbits were determined 
at the first capture during each month, and weight-length relationships 
were used to calculate condition indices, using the formula: C.l. = —~-i £ } 
L 3 
where W is the weight in grams and L is the length in decimeters (Bailey, J. A. 
19^7* MV/RL 10(7) :3)* The mean condition index for October (91 rabbits) was 
5-30, for November (102 rabbits) was 5-39, and for December (79 rabbits) was 
5-46. The differences among the means for the 3 months were not statistically 
significant at the 95 percent level of significance, although Bailey had 
found highly significant differences among the months November through March 
during the years 1964 through 1967- 
The monthly means for October, November, and December 1970 were all 
less than the means for the corresponding months of i 960 and 1969* The 
differences were significant at the 99 percent level of significance. These 
differences may indicate that the population was in a less favorable energy 
balance in 1970 than in the previous 2 years; or they may reflect a greater 
turnover of rabbits in the population, because the newer cottontails tend 
to have lower condition-index values than do cottontails that have been on 
the study area for a longer time. 
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