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SVh*>. 11 
MONTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
Glen C. Sanderson and Helen C. Schultz, Editors 
Urbana, Illinois November, 1965 Mo}. 8, No. 11 
1. Pheasant Populations and Land Use W. J. Francis, S. L. Etter 
Captures of pheasants by night1ighting in the Sibley Study Area during October 
and early November of 1965 totaled 385 birds in 8 nights of trapping. Distribution 
of captures by sex and age was as follows: 
Adult cfcf—14--3.6% Juvenile 1 29--33.5% 
Adult 99 — 92 — 23 . 9 % Juvenile 99 — 150 — 39.0% 
The ratio of 3*0 juveniles (both sexes) per adult female gives an index to 
the rate of production of young. This ratio is the same as in 1964, and is less 
than has been found in the years prior to 1964, in which it ranged from 3.2 to 5.0. 
Roadside summer counts of broods and adult hens both showed substantial dec/eases 
from previous years, as did the 1965 nesting study (Monthly Wildlife Research 
Letters, August and September, 1965)- From the low numbers of hens, broods, and 
nests, and the low ratio of young to adult hens, it appears that the recruitment 
of young was again slight, as in 1964. 
The percentage of cocks among the adults in the fall sample decreased from 
18.4 in 1964 to 13.2 in 1965 - This change indicates a greater relative mortality 
in cocks than in hens in 1 965 than in 1964. Taken in conjunction with the low 
numbers of hens, broods, and nests observed during the summer, the decrease in 
relative abundance of cocks is strongly suggestive of a high mortality and a 
correspondingly small breeding population. With a low recruitment of young in a 
reduced breeding population, there appears to have been a substantial decrease in 
the population on the study area from the numbers present in 1964. 
The departure of the juvenile sex ratio from unity (86d’d': 1 OO99) , although 
greater than usually found, is not significant. 
2. Manipulation of pheasant Habitat G. B. Joselyn 
Data presented in the October 1965 Monthly Wildlife Research Letter (Vol. 8, 
No. 10, page 2) showed that during the years 1 96 3 — 6 5 there was a higher rate of 
pheasant nest destruction by mammalian predators on seeded roadsides than in the 
other cover types on the Sibley Study Area collectively. Further consideration is 
given here to predation which occurred on the seeded roadsides and in unharvested 
hayfields on the study area. Unharvested hayfields are felt to be the cover most 
similar to that which exists on the seeded roadsides. 
In 1963, 46 percent of all nests found in unharvested hayfields (38 of 82 
nests) searched in conjunction with studies of pheasant populations and land use 
were preyed upon by mammals; 34 percent of the nests found on the seeded roadsides 
NATURAL HISTORY SURVEY 
