should be favored by the sustained yield policies 
of forest management in effect there. 
Studies made in 1949 and 1950 in eight 
counties in the Shawnee National Forest and one 
adjacent county show that deer were present on 
only about 203,000 of the 439,087-acre area exam- 
ined, table 5. Resident landowners provided con- 
siderable information in drawing the line between 
occupied and unoccupied ranges. In addition, 
foresters, conservation officers, and interested 
sportsmen contributed helpful sight records. 
From data given in table 5 can be calculated 
the proportion of each of several cover types 
occupied by deer: 43.5 per cent of the upland hard- 
woods, 49.8 per cent of the bottomland mixed hard- 
woods, and 87.8 per cent of the pin oak flats. As 
the early deer releases were made indiscriminately 
in these three cover types, it is thought that the 
greater use of the pin oak flats showed that deer 
preferred this type. The upland hardwoods, which 
comprised the largest land area by far, appeared 
to be least desirable. It is believed that most of 
the unoccupied area is capable of supporting deer 
herds. Some of the deer removed from areas in 
which the animals were too numerous or destructive 
were released in parts of this unoccupied area 
during the winters of 1951-52 and 1952-53. 
Populations 
An effort to assemble population data on the 
various deer herds of Illinois was begun in the 
spring of 1947. Reports received from conser- 
vation officers at that time indicated that deer 
were showing a general increase and appearing in 
counties not occupied by them in the recent past. 
Deer population estimates were made for the 
winters of 1949-50 and 1950-51. These were 
based on data obtained from three sources: (1) 
conservation officers, (2) aerial censuses of the 
Rock River range, and (3) deer drives on the 
island of the Horseshoe Lake Game Refuge. The 
data indicated state-wide populations of about 
2,550 in 1949-50 and more than 3,075 in 1950-51. 
The distribution of the 1950-51 deer populations 
by counties is shown in fig. 11. Location of the 
ptincipal deer ranges is shown in fig. 12. 
Reports from conservation officers indicate 
the nature of the population trend during the 1949- 
1951 period, table 6. The number of counties for 
which increased deer populations were reported 
in both 1949-50 and 1950-51 was far greater than 
the number for which reduced populations were 
teported. In addition, deer were reported present 
12 
in six more counties in the winter of 1950-51 than 
in the previous winter. 
Population on the Rock River Range.--The 
earliest information on the deer population that 
occupied the Rock River range, fig. 12, following 
the escapes and releases mentioned previously, 
was obtained from Dr. David H. Thompson of the 
Forest Preserve District of Cook County on 
August 20, 1953. Dr. Thompson reported that, 
while he was conducting a full-time study of the 
Rock River from Sterling to the mouth of the 
Kishwaukee River in 1925 and 1926 for the Illinois 
Natural History Survey, he learned from the local 
people much about the number of deer in the area. 
After noting this type of information for 2 years, 
he estimated a population of about 200 deer for 
Ogle and Winnebago counties between Dixon and 
Rockford. 
Deer on the Rock River range were censused 
from the air in February of 1947, 1949, and 1950, 
and in December of 1950. Swears (1948:12) de- 
scribed the initial survey, which was conducted in 
Ogle and Winnebago counties by Willet N. Wandell 
of the [llinois Natural History Survey and William 
L. Preno of the Illinois Department of Conserva- 
tion. Aerial photographs were taken by Wandell 
on this survey, fig. 1 and back cover. 
Estimates based on a complete aerial survey 
of brushy and wooded areas in which deer normally 
ranged proved to be of greater accuracy than 
estimates obtained by sampling the area along 
predetermined flight strips. Figures derived from 
the strip census were found unreliable because 
this type of census did not eliminate the bias 
introduced by the extremely uneven distribution 
of deer on the Rock River range in winter. 
In an unpublished report, Wandell stated that 
the area censused during the first survey, in 
February, 1947, comprised 8,110 acres of wood- 
land in close proximity to the Rock River in Ogle 
and Winnebago counties. Observations revealed 
a total of 655 deer in the censused area. Wandell 
estimated that three of every four deer in the 
censused area were seen and recorded and cal- 
culated the population for the censused area as 
872. He estimated that 67 per cent of the deer 
range in these two counties had been surveyed, 
and he apparently assumed that the deer density 
in the uncensused area was equal to that in the 
censused area. Using the data then available, 
he calculated that the deer population of Ogle 
and Winnebago counties was 1,295. The writer 
believes that this initial estimate of the popu- 
lation was too high, for subsequent surveys 
