MONTHLY WILDLIFE RESEARCH LETTER 
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Illinois Federal Aid Projects W-66-R, V/- 87 -R, and W-88-R 
Department of Conservation and Natural History Survey, Cooperating 
Glen C. Sanderson and Eva Steger, Editors 
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Champaign, Illinois 
April, 1982 
Vol. 25, No. A 
Manipulation of Pheasant Habitat - W-66-R R * E * ' ,arner 
The survival of pheasants on the Sibley Study Area (SSA) during the 1980 s 
was recently analyzed with the assistance of S. L. Etter, former leader of the 
pheasant project. One aspect of the analysis focused on factors that were 
potentially important in determining rates of survival for several thousand 
pheasants backtagged from 1962 through 1965. This period is historically 
important because of the rapid transition to the row-crop monoculture that 
currently prevails in central Illinois. 
For pheasants captured and backtagged in the falls of 1962 through 1965, 
rates of observation were considered relative to year-to-year changes, location 
of capture site on the SSA, and characteristics of molt, age, and weight. The 
average percentage of birds observed alive after 1 January of each year 
(following capture) was 423 for adult hens, 27% for juvenile hens, and 7.9^ 
for juvenile cocks. 
The relative importance of the variables considered for each sex and age 
cohort was determined by a regression model, MANOVA. For adult hens (N - 714), 
molt stage at capture, date of molt initiation, and body weight were not 
significantly related (P_ > 0.05) to the observation rate. For juvenile hens 
(N = 1,445), weight was also not related to observation rates, but age at 
capture and date of hatch were significantly (P < 0.05) related to rates of 
observation. Date of hatch--the most important factor--indicates that 
earlier-hatched young are more likely to survive until winter. Controlling 
for other factors, for 2 groups of juvenile hens hatching 1 week apart, the 
older group would be predicted to have a 3% greater rate of survival through 
1 January following hatch. 
Two analyses were performed for juvenile cocks (N = l,356)-~one for cocks 
known alive at the onset of the hunting season and the other for cocks observed 
1 January or later (i.e., alive following the hunting season). In both analyses, 
weight, date of hatch, and age at capture were not related significantly to 
rates of observation. 
In next month's newsletter we will consider the importance of the location 
of the capture site on the SSA and survival--the importance of egress. 
