Vol. 23, No. 11 
Page 3 
» 
Respons es of Prair ie Chickens to Habitat Hanlpuiat ion-W-C 6 -R 
R.L. V.'estemeier, 
J.E. Buhnerkempe 
Since 1963, the spring counts of prairie chickens at Bogota have fluctuated 
from 1*0 to 206 cocks, with an 13-year mean of In the late 1360 's, a large 
increase in sanctuary acreage resulted in dramatic increases in the coc. 
population from 1969 through 1972 (Fig. 1). These increases were logistic and 
typical of responses by populations to substantial increases in habitat. During 
197li through 1976, however, the numbers of cocks dropped alarmingly. Reproductive 
performance and nest success of chickens declined during this period while, 
conversely, the pheasant population at Bogota was increasing. Since 1976 the 
population level of chickens has stabilized somewhat; a moderate increase was 
evident the spring of 19 r * 0 . 
Nest success, pheasant interaction, and weather (MWRL 22,(9)-3, 19( i ') : **» ant * 
14(7): 3 ) were among factors listed as affecting the population level. This report 
is the first of a series updating previous findings and analyzing the dynamic 
parameters for the population of prairie chickens in Jasper County. 
Hen numbers are recorded whenever possible along with tne count of prairie 
chicken cocks on booming grounds. Although hens frequent booming grounds much 
less regularly and predictably than cocks, hen counts may provide an index to 
population change some years. Significant correlations could not be found between 
hen numbers and population change, but several observations should be noted. 
First, during 3 of the 6 years of population increase since 1963, the ratio 
between cock and hen counts approached 1:1, respectively. However, the ratio 
increased to 2:1 or greater when the cock population was at peak levels (1^71 7 /% 
Secondly, a highly significant correlation (jr = 0.907, P <0.01) was found 
between the spring count of hens and the number of nests located the fo lowing 
summer. In 1977 and 1930, however, large drops in the number of nests located 
cannot be explained by decreases in the hen counts. Such possibilities as VU 
duplication of hen counts (same individuals counted on several booming grounds, 
( 2 ) nesting on areas not searched, ( 3 ) hens not nesting, or ( t) missed nests 
during annual search, may account for the variation noted in such years as jll 
and 1980 . 
The next report in this series will analyze and discuss egg hatchability 
and clutch size in relation to other prairie chicken population parameters. 
Ecology a nd M anagement of Whi te- t ai le d Deer ~ l,'“ ..*7~P 
Perhaps the tremendous change in the Illinois landscape following corn and 
oybean harvests is a factor in the timing of deer movement from summer to winter 
ange. This would be particularly true for deer native to the Grand Prairie 
f Illinois, where row crops occupy > 30 % of the land. 
