MONTHLY WILDLIFE RESEARCH LETTER 
i• 
v. 3 
no • Z 
J 
Department of Conservation and Natural History Survey, Cooperating 
T. G. Scott, Editor 
Urbana, Illinois 
March I960 
Vol. 3, No. 3 
W-30-R-13 R. F » Labisky 
An aerial census of the 37-square mile Sibley area during late February, 
I960, showed an average of 87.7 pheasants per square mile. A comparable aerial 
census during mid-January, 1957, yielded an average of 61.2 birds per square mile. 
Thus, the population of pheasants at Sibley was 43.3 per cent greater this past 
winter than it was in 1957. Cocks comprised 19.0 and 21.1 per cent of the winter 
populations in 1957 and I960, respectively. 
Pheasants in east-central Illinois were not seriously affected by the 
snow that accumulated over the area during February and March, I960. Field 
observations in Ford, Livingston, and McLean counties showed the pheasants to be 
in excellent physical condition during and after the heavy snows. Not a single 
dead pheasant whose death could be attributed directly to snow storms or to 
starvation was found. Autoposies of pheasants killed by vehicles along highways 
during early and mid-March showed the birds had an ample quantity of corn and weed 
seeds in their crops and heavy deposits of fat in their bodies. 
W-42-R-9 R. D. Lord, Jr. 
Analysis of data on the daily activity of cottontail rabbits indicates 
that rabbits begin their night's activity at about 5:00 p.m. CST and terminate 
at about 7:00 a.m. CST and that this occurs throughout the year regardless of the 
amount of daylight. Sunset slightly influences the beginning of rabbit activity 
(in summer it tends to start somewhat later), and sunrise appears to have no effect. 
For any one night, activity of rabbits is bimodal with the largest peak occurring 
at 4:00 or 5:00 a.m. The midnight lull may occur at any time from 10:00 p.m. 
until 2:00 a.m. The evening peak in winter is about 75 per cent of the early 
morning peak, but, in summer, it is only about 40 to 50 per cent of the early 
morning peak. 
This indicates that roadside censuses for rabbits should start according 
to standard time rather than in relation to sunrise. The extreme variability of 
activity of the same population indicates that a roadside census should be 
conducted for at least 60 miles and should be run on at least two different nights 
(or early mornings) for each census. A shorter route may be run repeatedly to 
attain 60 miles of observations. 
