MONTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
T. G. Scott, Editor 
Urbana, Illinois 
August 1959 
Vol. 2, No. 8 
W-30-R-13 
R. F. Labisky 
The standardized counts of pheasant broods taken on the Sibley area during 
July and August, 1959, indicated a decline in the production of broods when com¬ 
pared to similar counts taken during 1958. The number of broods observed along 
640 miles of roadside transect decreased from 240 broods in 1958 to 197 broods in 
1959, or 17.9 per cent. Comparable counts for 1957 showed a total of 194 pheasant 
broods. 
A description and evaluation of the method of capturing animals, particularly 
pheasants, by using bright lights at night was published as Illinois Natural History 
Survey Biological Note No. 40, July, 1959; the paper, which originated from this 
project, is entitled, "Night-lighting: A Technique for Capturing Birds and 
Mammals." 
W-42-R-9 R. D. Lord 
The August sample of rabbits taken for the study of cottontail reproduction 
showed an increased average litter size over the past 2 months. This is indicative 
of the effect of the increased average age of the breeding females. Older females 
tend to have the largest litters. The prevalence of pregnancy was the same as last 
August. Only 16 per cent of the breeding females were juveniles compared with 55 
per cent in 1958 and 56 per cent in 1959. Perhaps this is a result of the lower 
proportion of juveniles this August (39 per cent, compared with 58 per cent in 
1958 and 56 per cent in 1957). Because reproduction has been very close to last 
year's reproduction, the markedly lower proportion of juveniles in the August 
sample indicates a higher juvenile mortality this year. 
N-55-R-4 F. Bellrose 
This project was inactive during August. 
H- 56 -R -4 
G. Sanderson 
Preliminary tabulations of trapping data provide a basis for a fairly 
accurate delineation of the home ranges of opossums in east-central Illinois. 
Young-of-the-year females have home ranges that are only about half as large as 
"he average home range of young-of-the-year males. Adult females have home ranges 
^hat are approximately the same size as those of young-of-the-year males. Although 
only two adult males were retrapped six or more times each in three or more 
opt n 'lorn 
NATURAL 
HISTORY SIIRVFY 
