14 1 Hon ALU DUB LOON SB UL eee 
TABLE 1 
NUMBER AND PERCENTAGE OF ROUGH-LEGGED HAWKS 
OF VARIOUS PLUMAGE CLASSES* 
Winter Dark Intermediate Light Total 
1964-65 A3e(3575) 12 01-0;0) 66 (54.5) 125 
1965-66 94 (29.4) 64 (20.0) 162 (50.6) 320 
Total hi 7a (3x81) Tome?) 228 (bis 44] 
* Numbers in parenthesis indicate percentage. 
I think that the frequencies are essentially the same for 
the two winters. 
Dark rough-legs comprised 31.1 percent of the total 
sample. This frequency was obtained using a system of 
three color classes, rather than the two-class system (i.e, 
dark and light) more commonly employed for this 
species. In R. R. Graber and J. S. Golden’s (Illinois Natural 
History Survey Biological Notes 41, 1960, page 22) analysis 
of the 1903 to 1956 Christmas bird counts for Illinois they 
stated that dark individuals had been recorded only rarely. 
This was obviously not the case during the two winters of 
my study, since aproximately one-third of the birds in my 
study area were dark rough-legged hawks. 
My study of rough-legged hawks was supported by the 
Frank M. Chapman Memorial Fund, American Museum of 
Natural History. The Museum also provided a spotting scope 
for my use. William E. Southern, Mary Sue Schnell, R. Steven 
Gourley, and John L. Weeks assisted me in various ways 
during the project. 
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