Vo 1. 23, No. 4 
Page 2 
Probability of occurrence for each of the 4 categories was based on total trap 
captures. These values wer& used in a polynomial expansion to calculate expected 
frequencies for all possible combinations of the 4 categories. Chi square analyses 
indicated that these comparisons were significant in all cases except during 
autumn on Danville B when sample sizes were low. 
In general, home ranges of females overlap less than expected with other 
breeding and nonbreeding females whereas adult males overlap more than expected 
with other adult males and nonbreeding females. Females apparently tend to avoid 
other females whereas adult males do not avoid other males. Nest box and leaf 
nest data support this phenomenon; 2 females are virtually never captured in a 
nest box or leaf nest whereas 2 males are ccmmonly captured together. 
Although definite conclusions about social behavior in fox squirrels cannot 
be drawn from this analysis, female spacing in the habitat may plan an important 
role in density regulation. Further study is warranted because the introduction 
of additional life-supporting elements into a squirrel population, such as nest 
boxes or supplemental food, may be useless if intrinsic social factors exclude 
excess individuals from the population. 
Responses of Prairie Ch?ckens to Habitat Manipu1 ation - W-66-R R. L» Westemeier 
Prairie chicken populations near Bogota (Jasper Co.), Farina, Kinmundy (both 
Marion Co.), Mt. Erie (Wayne Co.), and Hoyleton (Washington Co.) were censused 
this spring (I 980 ). These areas have been censused annually for 18, 18, 17 > 18, 
and 12 years, respectively. As in past years, booming ground surveys at Bogota 
were supplemented with observations by visitors in blinds almost daily from 25 
March through 29 April. 
Counts in I 98 O totaled I 67 cocks, up 55% from the 112 cocks censused on the 
5 areas in 1979. Assuming a 50:50 sex ratio, there were 334 native prairie 
chickens in Illinois in the spring of !930--a gain of over 100 birds since last 
spring. 
The managed areas, those with sanctuaries for nesting (Bogota, Farina, and 
Kinmundy), showed an increase of 44% over last spring. The Bogota flock increased 
from 68 cocks in 1979 to 92 cocks in 1930, up 35%; the 1980 count is 98 % of the 
long-term mean. The flock at Farina increased from 22 cocks in 1979 to 38 cocks 
in 1980, up 73% and 126% of the long-term mean. Near Kinmundy, the flock increased 
from 18 cocks to 26 cocks, up 44% but 177% of the long-term mean; this flock was 
down to only 6 cocks in 1971* A combination of these 2 flocks in Marion County 
this spring (64 cocks) represents the highest population level on record. 
Although unmanaged flocks at Mt. Erie and Hoyleton remain at precariously 
low levels, they showed larger percentage gains than flocks on the managed areas* 
The birds at Mt. Erie were not located in 1979 despite thorough searches on 2 
excellent mornings. Noise from oil wells hinders censusing of this Wayne County 
flock. By intensive checking at Mt. Erie this spring (I 98 O), 4 cocks and 3 hens 
were observed in and near a 50-acre redtop-timothy seed meadow. Fortunately, 
