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MONTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
Glen C. Sanderson and Helen C. Schultz, Editors 
Urbana, Illinois January, 1966 Vol. 9, No. 1 
1. Pheasant Populations and Land Use W. J. Francis, S. L. Etter 
Fall populations of pheasants on the Sibley Study Area have been estimated 
on the basis of the proportions of marked birds found in hunters' bags (Lincoln 
Index) for the years 1962, 1 96 3, and 1964. Populations were estimated at 15,224 
in I 962 and at 7,071 in 1964. In 1 965 , hunting success was so low, and tag returns 
so few, that no estimate of the size of the fall population could be made by the 
above method. The margin of error in such estimates is considerable, except for 
large samples, because only the cock population is directly estimated, and the 
estimate of the hen population is derived indirectly. Sampling errors in the 
estimation of the numbers of cocks are compounded by errors in the estimate of the 
ratio of hens to cocks. 
Another index of population size is available in roadside counts of pheasants 
during the summer. Normally, about 75 percent of the fall population is composed 
of juveniles (71 - 80 percent in the last 5 years). The preponderance of juveniles 
suggests that the number of broods and/or chicks seen on standardized transects 
during July and August will be nearly proportional to the total population the 
ensuing fall. 
A comparison was made between the following four indices of the fall popula¬ 
tions for the years 1962-64: 
1) Prehunting population calculated from tag returns in hunters' bags. 
2) Number of broods observed on 640 miles of road transects. 
3) Number of chicks in observed broods (calculated from the number of broods 
X the average number of chicks in complete broods seen). 
4) Total number of birds observed on 640 miles of road transects. 
The average of each index for the 2 years 1962 and 1963 (both having fall 
samples greater than 1,000 birds) was taken as a standard and designated 100. The 
relative sizes of the populations, in percent of the 1962-63 average, was calculated 
for each of the above indices (Table 1). 
Table 1. Relative sizes of fall populations of pheasants on the Sibley Study Area, 
as calculated for different indices. 
Year 
Tag 
Returns 
Number of 
Broods 
Number of 
Chicks 
Total Number 
of Birds 
1962 
119 
109 
113 
110 
1963 
81 
9» 
87 
90 
1964 
55 
70 
61 
KAUm HISTORY Sur-VEY 71 
FEB E 5 1866 
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