100 : 
CENTRAL ILLINOIS 
90 SOUTHERN ILLINOIS 
XX 
SOK 
woteten 
O 
es 
te! 
00; 
on 
SSS 
O> 
SSC 
2 
20.0 @ 
me” 
es 
COOOOS 
FREQUENCY (PER CENT OF COUNTS) 
oi 
[e) 
20 ee 
10 : 
a : 
(e) = <] 
/9 Os /9 YO /9 65 /9 Ex /9 30 
Fig. 10,—Frequency of occurrence of the sparrow hawk in central and southern [Illinois calculated for 5-year periods be- 
ginning in 1905 and ending in 1954. The year indicates the beginning of the 5-year period. 
—O— CENTRAL ILLINOIS 
—4— SOUTHERN ILLINOIS 
BIRDS 
fe) 
i) 
oO 
NUMBER 
a 
05 *\\ 
fe) foto) i} 
Aa Pees 
/ / / /9 / /9 / / / /9 19 
905 Io 975 20 825 30 "35 i 925 So Ss 
Fig. 11.— Average numbers of sparrow hawks reported per observer-hour in central and southern Illinois, 1903-1955. 
11 
