IViAK 8 1982 
tiRpa«?v 
MONTHLY WILDLIFE RESEARCH LETTER 
Illinois Federal Aid Projects W-66-R, W- 87 -R, and W- 08 -R 
Department of Conservation and Natural History Survey, Cooperating 
Glen C. Sanderson and Eva Steger, Editors 
Champaign, Illinois 
February, 1982 
Vol. 25, No. 2 
Manipulation of Pheasant Habitat - V/-66-R -• Warner 
If metabolites of agricultural insecticides have contributed significantly 
to reducing the size of pheasant broods over the past 3 decades, then 1 possible 
manifestation would be a reduced rate of hatch. For example, controlled studies 
have demonstrated that pheasants that ingest high levels of chlorinated hydro 
carbons produce fewer eggs and fewer of the eggs hatch. 
The clutch size (incubated nests) and number of eggs hatched per successful 
nest for pheasants near Sibley apparently have remained relatively constant 
since the mid-1950's (Table 1). Therefore, if insecticides have impaired 
survival of pheasant chicks, the chicks appear most vulnerable in the post 
embryonic stages. 
The "clean farming syndrome"--high use of chemicals on farmland--a1ters 
habitat and therefore tends to reduce the rate of survival by pheasant chicks. 
Next month we will discuss the components of habitat essential for pheasant 
broods and how they are affected by changing agricultural practices. 
Table 1. The 
average number of pheasant 
eggs incubated 
and hatched per nest 
near Sibley, 1 
Illinois, 1955-81.-- 
X eggs 
per nest 
Period 
i ncubated 
Hatched 
N 
1955-59 
9.9 
8.5 
297 
1960-64 
9.9 
8.6 
684 
1965-69 
10.1 
9.0 
200 
1970-74 
9.3 
8.3 
236 
1975-81 
9.3 
8.3 
58 
^Oata for 1955-72 from the Sibley Study Area; 1973-81 from the Ford County 
Management Unit. 
