Table 8. - Sex ratios of deer trapped, found dead, or observed in the field on the Rock River range, 
principally in Ogle and Winnebago counties, Illinois, 1947-1951. 
Period Bucks | Does Buck: Doe Ratio Source of Data 
1947-1951 78 80 1:1.:03 Live trapping 
1948-1951 98 99 ELOL Fatality counts 
1948-1951 152 146 1:0.96 Field observations 
Total 328 325 1:0.99 | — 
Table 9. - Sex ratios of deer trapped on the is- 
land of the Horseshoe Lake Game Refuge, 
Alexander County, Illinois, 1946 through spring 
of 1953. 
Buck: 
Year Bucks | Does See 
1946-47 16 | 9 1:0.56 
1947-48 32 etog «| 10'81 
oo ae ar 1:1.25 
1950-51 15 fe oiae §| eee S80 
1951-52 19 [neem Peer sO 
1952-53 4 (Pee ee gine 
fot | 90 fh 7 | a s2 
Table 10. - Data on sex and age classifications 
of 244 deer seen on the Rock River range, princi- 
pally in Ogle and Winnebago counties, Illinois, 
1950. The doe to fawn ratio was 1:0.916. 
5 ee Number Per Cent of 
Classification Seen Total Seen 
Adult or 
yearling bucks 85 34.8 
Adult or 
yearling does 83 34.0 
Fawns 76 31.2 
Total 244 | 100.0 
bucks and 80 does were caught; of the fatalities 
of all kinds recorded in this area, 98 were among 
bucks and 99 were among does; and, of deer 
observed in the field, 152 were bucks and 146 
were does. 
The computed sex ratio for the 328 bucks 
and 325 does listed above is 1 buck to 0.991 doe. 
C. W. Severinghaus of the New York State Conser- 
vation Department, in a letter dated September 
21, 1951, indicated that the buck-to-doe ratio of 
11,065 fawns, less than 9 months of age, killed 
by non-selective agents in New York was 1:0.960. 
Sex ratio data for the deer trapped on the 
island of the Horseshoe Lake Game Refuge were 
meager and they were inconsistent from year to 
year; nevertheless, it is thought that they are 
worthy of record, table 9. In the first 2 years for 
which records are available, bucks outnumbered 
does, but in the last three winters the number of 
does caught was considerably greater than the 
number of bucks taken. Perhaps the excessively 
high deer populations in the more recent years 
tesulted in pressures which caused more bucks 
than does to leave the island. Observations on 
the Rock River range, table 8, do not indicate 
that the trapping technique, as used there, was 
selective for does. 
Deer fatalities, from the fall of 1948 to the 
spting of 1951, provided some data on the sex 
tatios of deer in widely scattered sections of 
southern Illinois. Of 35 deer that died from a 
variety of causes, but most of them as a result of 
highway accidents, 20 were bucks and 15 were 
does, a 1:0.75 ratio. The losses occurred in 10 
southern [Illinois counties, chiefly in and near the 
Shawnee National Forest. It is realized this is a 
small sample for so large an area, and record is 
made of it here largely for addition to such future 
data as may be collected. 
Data on the age ratios of deer were obtained 
in the Rock River range from field observations 
in the summer and fall of 1950; 244 deer were 
seen clearly enough to be classified as to sex 
and age, table 10. The relative length of muzzle 
was used to distinguish fawns from older deer. 
Of the adult and yearling deer, 85 were bucks 
and 83 were does; the buck-to-doe ratio was 
1:0.976. The doe-to-fawn ratio was 1:0.916. 
The aerial census in December, 1950, indi- 
cated a deer population on the Rock River range 
of 994; thus, the 244 identified deer made up a 
sample of 24.5 per cent of the estimated total 
population. It was felt that this sample gave an 
accurate index of the doe-to-fawn ratio and sug- 
gested good productivity in this area for 1950. 
Movements 
Seasonal movements of the deer on the Rock 
River range were evident in spring and fall of 
15 
