moi thly wildlife research letter 
Department of Conservation and Natural History Survey, Cooperating 
Glen C. Sanderson and Helen C. Schultz, Editors 
Urbana, Illinois March, 1 966 Vol. 9 , No. 3 
1. Pheasant Populations and Land Use W. J. Francis, S. L. Etter 
Only 129 pheasants were captured in nightlighting operations on the Sibley 
Study Area from December 28, 1965, to January 24, I 966 , compared with 154 in the 
winter of I 965 and a high of 413 in the winter of 1963- The most important popu¬ 
lation statistic obtained from winter-trapped samples is the ratio of juvenile to 
adult females, which is used with the corresponding ratio obtained from fall- 
trapped samples to estimate the survival rate of juvenile females relative to that 
of adult females. To determine whether the population data collected in the last 
4 years show significant differences in the survival rates thus calculated, a chi- 
square test was made of the hypothesis that the survival rate of juvenile females 
relative to that of adult females is constant. Table 1 compares the age composi¬ 
tions of the observed posthunt samples of hen pheasants with the age compositions 
of the posthunt samples that would be expected, in each of the 4 years, assuming 
that the relative survival rate is constant, and equal to that calculated from the 
age ratios for all 4 years. 
The data show no significant difference between observed and expected propor¬ 
tions of juvenile females in the posthunt samples. The important ecological 
significance of this finding (if substantiated by examination of additional data) 
is that the relative rates of mortality and survival of juvenile females from fall 
to early winter are fixed characteristics of the population and do not appear to 
depend on either environment or population density. In our study area we can 
expect juvenile hens to survive only half as well as adult hens, i.e., if 100 per¬ 
cent of the adults survive until February, 50 percent of the juveniles will; if 
only 60 percent of the adults survive (shown by winter censuses to be a fair 
approximation of the usual situation), then about 30 percent of the juvenile hens 
also survive. A calculation made prior to the beginning of winter night1ighting 
indicated that an age ratio of 84 juvenile hens to 1 00 adult hens would be found 
in the posthunt sample in 1966 ; the actual age ratio found was 86 juveniles to 
100 adults (Table 1). 
Consideration of the magnitude of fall and early-winter losses of females as 
indicated by these calculations leads to the question of whether hunting could 
replace some of the natural mortality. A minimum of 26 juvenile hens per square 
mile, and a probable total of about 60 hens per square mile, were lost between 
October, I 965 , and February, 1 966 - It would be informative to make a practical 
test of the proposition that a moderate harvest of hens would be compensated by a 
reduction in natural mortality. 
A secondary implication of the above findings is that winter night1ighting 
samples, with the population levels attained during the past 4 years, do not 
provide any information on changes in survival rates between years. 
