MONTHLY WILDLIFE RESEARCH LETTER 
Department of Conservation and Natural History Survey, Cooperating 
4 
Helen C. Schultz, Editor 
(Jrbana, Illinois 
May, 1975 
Vol. 18, No. 5 
Ecology an d Management of Squirrels 
C. M. Nixon, 
S. P. Havera 
The intermediate timber harvest on the Massac sale area was described In 
the last report (MWRL 18(4)) in terms of its effect on food and shelter for 
squirrels. In this report we will consider the effect of the timber harvest 
on the squirrel populations. Sixty percent of the squirrel population on the 
area was composed of gray squirrels, and there was no change in this proportion 
of gray squirrels after cutting. 
The timber cutting appeared to affect gray squirrels more than fox squirrels. 
Survival rates for all sex- and age-classes of gray squirrels averaged 40.0 
percent between May 1973 and March 1974, the period when the timber was being 
cut and removed. In contrast, survival of all sex- and age-classes of gray 
squirrels averaged 86.7 percent between March 1974 and March 1975* after cutting 
was completed. Nine of 10 fox squirrels survived the timber cutting. 
Movement patterns also changed after cutting, but differed between species. 
There was a significant (P<0.05) increase in livetrap captures of fox squirrels 
after cutting for traps 1-9, located adjacent to uncut mature timber. Of 
eight adult fox squirrels, five experienced no signficant shift in home range 
and three moved south to the edge of the sale area adjacent to the uncut forest. 
Of two juvenile fox squirrels, one remained within the cut and the other 
disappeared from the study area. 
For gray squirrels, there was a significant increase (P<0.05) in their 
capture rates in traps 29 - 37 > which traverse the center of the cutover area. 
Five of 12 adult gray squirrels captured before cutting began remained on 
the same ranges, 1 moved to the adjacent uncut forest, and 6 disappeared. A11 
three juvenile gray squirrels marked prior to cutting disappeared from the study 
area after cutting. 
In terms of total density of squirrels, the timber cut appeared to have 
little or no effect on the squirrel population. The estimated density of 
squirrels was 49 in 1973 and 47 in 1975* We actually captured six more squirrels 
in 1975 ( 31 ) compared with 1973 ( 25 )* 
Apparently, the Massac sale area did not support a particularly high density 
of squirrels prior to the sale (1.1 per acre). At this density, the loss of 
nearly half the nest dens and an appreciable amount of food did not lower the 
