MONTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
T. G. Scott, Editor 
Urbana, Illinois 
November 1958 
Vol. 1, No. 11 
W-30-R-12 R. F. Labisky 
An analysis of the sex and age composition of the 1956, 1957, and 
1958 pre-hunt populations of pheasants on the intensively farmed Sibley area 
is presented in the following table. The data were collected during night-light 
trapping operations in October and early November of each year. 
1956 
1957 
1958 
Percentage of Cocks in 
Population*- 
1*6.8 (263) 
1*1.5 (212) 
1*0.7 (351*) 
Percentage of Juveniles 
in Population*- 
82.5 (263) 
71.2 (212) 
78.2 (351*) 
Juveniles per Adult Hen*-*- 
6.8 (32) 
3.2 (1*7) 
l*.l* (63) 
* Sample sizes (total number of pheasants) in parentheses. 
**• Sample sizes (number of adult hens) in parentheses. 
The findings indicate the annual rates of productivity. The rates of 
productivity for 1956, 1957, and 1958 appear to show some correlation with 
weather conditions during the nesting seasons. Productivity was highest in 1956, 
a year characterized by normal weather conditions during the nesting season. 
In 1957, excessive rainfall during the nesting season coincided with a low rate 
of productivity. In 1958, the nesting season was characterized by normal weather 
during the period of nest establishment, but during the peak of nest hatching, 
rainfall was abnormally heavy; productivity in 1958 was only moderately good. 
It should be emphasized, however, that although weather does exert an influence 
on annual reproduction, it is only one of many factors affecting the complex of 
growth and maintenance of pheasant populations. 
OCT 9 1959 
NATURAL 
HISTORY SURVEY 
LIBRARY 
