NATURAL Ki$iU;u J.i.'LT 
MAY 1 i 1971 
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MONTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
Glen C. Sanderson and Helen C. Schultz, Editors 
Urbana, Illinois 
April, 1971 
Vol. 14, No. 4 
1. pheasant Populations and Land Use S. L. Etter, 
R. E. Greenberg 
Preliminary criteria for distinguishing juvenile and adult pheasants in 
east-central Illinois, based on measurements of proximal (innermost) primary 
feathers, were presented in MWRL 13(3):1* These preliminary criteria were 
based on data obtained from pheasants captured during the year I 969 - 7 O. A 
second year's data on proximal primaries were collected during the fall and 
winter of 1970-71• Mean proximal-primary shaft diameters (PPSD) and 
standard deviations for each sex- and age-class were calculated for each 
season and year. As no significant differences in mean PPSD between years 
could be demonstrated, the data for the 2 years were combined, and revised 
0 criteria for separation of age-classes were calculated. 
A sample of 307 cocks collected during October and November, 19&9 ar, d 
1970, separated at 3.21 mm (0.1 265 inch) with 92 percent reliability. A 
sample of 46 cocks collected during January and February, 1970 and 1971> 
separated with 98 percent reliability at the same measurement. 
A sample of 285 hens captured during October and November, 19&9 ar *d 
1970, separated at 2.91 mm (0.1145 inch) with 90 percent reliability. A 
sample of 234 hens captured during January and February, 1970 and 1971 > 
separated at 2.86 mm (0.1125 inch) with 92 percent reliability. 
The lower degree of reliability of age separation of both sexes in fall, 
compared with winter, and the smaller separation measurement of hens 
captured in winter, compared with those captured in fall, apparently resulted 
from the fact that the mean PPSD of juveniles in winter samples were 
significantly smaller (£<^0.01) than those of juveniles in fall samples. 
Further examination of these data revealed that the PPSD of juveniles 
increased significantly (P<0.01) with seasonal progression, that is, the 
proximal primary feathers of juveniles that hatched and, consequently, 
molted early in the nesting season were smaller when fully grown than those 
of juveniles that hatched later. Conversely, the PPSD of adults decreased 
significantly (£<0.05) with advancing dates of molt initiation. 
Although there is no apparent explanation for these seasonal changes in 
| PPSD, it seems likely that the smaller mean PPSD of juveniles in winter, 
compared with fall, resulted from lower fal1-to-winter survival rates of 
late-hatched juveniles (with large primary feathers), compared with 
early-hatched juveniles. 
