HMIIM. BSIWI 9» W 
SEP 8 1981 
UB R#RV MONTHLY WILDLIFE RESEARCH LETTER 
Illinois Federal Aid Projects W-66-R, W-87-R, and W-88-R 
Department of Conservation and Natural History Survey, Cooperating 
Glen C. Sanderson and Eva Steger, Editors 
Urbana, Illinois 
August, 1981 
Vol. 2k , No. 8 
Ma nipulat ion of Pheasa nt Habita t ~ W-66-R R. E. u arner 
Cock call counts in May, 1981 on 5 study areas in east central Illinois, 
compared with 1980, indicated that the number of cocks was nearly stable on 
Anchor and Harwood areas and declined moderately on Prairie Green, the Sibley 
Study Area (SSA), and Ford County Management Unit (FCMU) (Table 1). Spring 
visual roadside counts on the SSA indicated 6.7 cocks per 100 miles of driving, 
a decline from 16.5 cocks per 100 miles observed in 1930. On the FCMU, visual 
counts in 1931 indicated 18.3 cocks per 100 miles, a decline from 23-1 cocks 
per 10Q miles in 1 S)80. 
Although indices of cock abundance declined in 1931 from the previous year, 
the density of breeding hens was estimated to be nearly identical for l980 and 
1981 when adjusted for winter sex ratio counts. Breeding populations on the 
study areas would probably have been greater in 1981 than in 1930 had there 
been no drought in central Illinois during the reproductive season of 1980. 
Table 1. Cock calls per 2-minute stop for 5 study areas In east-central 
Illinois, 1976-81. Numbers represent averages of the 5 highest counts per stop 
per year. Department of Conservation personnel assisted with the audio censuses. 
Area 
1976 
1977 
1973 
1379 a 
1980 
1981 
SSA 
12.8 
2.8 
2.0 
2.8 
3.7 
1.9^ 
FCMU 
22.9 
7.3 
6. k 
6.T 
10.1 
7.2 
Anchor 
19.9 
5.7 
k.2 
2.5 
2.5 
3.1 
Prairie Green 
28 . k 
9.2 
3.0 
8.0 
9.2 
8.0 
Harwood 
11.8 
7.1 
6.1 
5.5 
7.6 
7.9 
a T)ue to 
unusually poor 
counting 
conditions, 
averages were 
computed 
for the 
3 highest counts. 
b f>nly 3 counts were made; conditions were less than optimal. 
