Fig. 13. -- Remains of a deer that showed 
signs of having succumbed to a pack of domestic 
dogs on the Rock River range. 
Mortality 
Recent censuses on the Rock River range 
have pointed to a stable resident deer population 
there. Productivity has been shown to be good; 
no confirmed report of emigration beyond the limits 
of the range has been brought to light. The rel- 
atively stable population on this range has largely 
been a consequence of a mortality that balanced 
the productivity. 
Many data on deer mortality were furnished 
by conservation officers, in particular, Officer 
Paul Beebe of Forreston, who provided most of 
the records for the Rock River range. Other in- 
formation was obtained through direct observation 
in the field and from resident farmers. 
Of the known causes of mortality among deer 
in Illinois, highway accidents were the ones that 
most frequently came to attention, table 12. Ap- 
proximately half of the fatalities recorded were 
attributed to motor vehicles. Deaths recorded as 
tesulting from poaching were 15 times as many 
on the Rock River range as elsewhere in the state. 
On this range, high population densities were 
present over a larger area than elsewhere, and 
the deer were more readily accessible to poachers. 
Poaching was undoubtedly a much more frequent 
mortality cause than was indicated by the records. 
Poachers usually took precautions to conceal 
evidence of their activities; therefore, such losses 
frequently went unnoticed. Losses resulting from 
attacks by dogs, fig. 13, were also thought to 
Fig. 14. -- Two bucks on the Rock River range 
that died after having locked hors in a fight that 
took place during the breeding season. 
have been higher than indicated by the figures, 
because old evidence of dog kills was not readily 
identified, and cause of death was listed as un- 
known, when any doubt existed. A very small 
loss occurred from antler locking when bucks 
fought during the breeding season, fig. 14. 
Condition of Herds 
During the period of this investigation, the 
condition of the deer throughout Illinois appeared 
excellent, except for those animals inhabiting the 
most heavily populated area on the Rock River 
range and the island of the Horseshoe Lake Game 
Refuge. 
The degree to which food plants have been 
browsed may be used as an indicator of the state 
of balance existing between deer and their food 
supply. If the deer population does not exceed 
its food supply, such marked evidence of close 
feeding as a browse line, at the greatest height 
to which the deer reach when standing on all 
fours, will not be easily discerned on the more 
desirable food plants. 
On the Rock River range, only one small 
atea, consisting of the Harry Severson and the 
Hugh Funderburg estates, fig. 12, exhibited from 
the beginning of this study a marked browse line, 
fig. 15, indicative of restricted food resources. 
These adjoining estates, encompassing about 4 
square miles of forest and agricultural range, are 
located about 7 miles southwest of Rockford. 
17 
