Vol. 13, No. 12 
Page 3 
individuals moved 0.5 to 1 mile. In 1965, only one movement within the 0.25- to 
0.5ymile range was recorded (one Individual); three movements within the 0.5- to 
1-mile range were recorded (three individuals); and four movements were >| mile 
(two individuals). These data reflect the apparent nomadism among a small 
percentage of the cock population during the summer. 
5. Responses of Prairie Chickens to Habitat Manipulation R. L. Westemeler 
On the Bogota Study Area during the period of I 963 - 70 , distances between 
174 prairie chicken nests and the estimated centers of the nearest booming 
grounds have ranged from 72 yards to 1,700 yards, with respective mean, mode, 
and median distances of 364+ 253 (SD) yards, about 240 yards, and about 300 
yards. Thus, few nests occur within 100 yards of, or farther than 600 yards 
from, centers of booming grounds. 
In 1968 and I 969 , evidence indicating the existence of a preferred zone 
for nesting was obtained in situations involving booming grounds surrounded 
with nesting cover. Nests were found in radial patterns encircling several 
booming grounds. Although no distinct spokes-in-a-wheel patterns were found 
at Bogota in 1970, as were found in 1968 and 1969 , the most frequently occurring 
distance of about 240 yards became even more clearly evident than formerly. In 
contrast to average distances exceeding 500 yards between booming grounds and 
prairie chicken nests in 1963-64, when the population was declining, the average 
distance has progressively decreased (275 yards in 1970) as the Bogota flock 
increased. This gradual change in nest dispersion relative to the booming 
grounds has occurred because of (1) the provision of suitable sites for booming 
(and the establishment of nesting cover) on the sanctuaries and (2) the 
apparently greater advantages accruing to reproduction from the presence of 
nesting cover close to and surrounding booming grounds. 
6. Rabbit Management G. Rose 
Estimates of population density of cottontail rabbits on the 100-acre (40- 
hectare) 4-H Camp Area at Robert Allerton Park, based on livetrapping conducted 
during the first 10 days of December 1970, were 92 by the Schnabel method, 1 74 
by the geometric maximum likelihood estimate (MLE-G), and l93 by the maximum 
likelihood estimate from a regression of the logarithm of the number of individual 
in a frequency class on frequency of capture (MLE-R). The MLE-R is considered 
the best method of estimation. 
The fall population estimates (MLE-R) of 192 for October, 307 for November, 
and 193 for December, 1970, show a continuation of the relatively high densities 
on the study area that have existed since 1 966 , after several years of low fall 
densities (1962 through 1965 ) and a period of high fall densities (1956 through 
The data did not show any mortality of the October-captured rabbits between 
the October and November trapping periods. This is consistent with the corre¬ 
sponding data from 1969 , which did not show any mortality for the same period, 
and from 1 968 , which showed a mortality of 4 percent. The December data, however, 
indicated a 31 percent mortality for the November-captured anfmaff between the 
November and December trapping periods. The corresponding mortality in 1 969 was 
54 percent. Thus, the same pattern of low mortality in October and high mortality 
in November continued this year. 
