Vol. 23, No. 6 
Page 2 
Anchor 
19*9 
5*7 
4.2 
2.5 
3.0 
20.0 
Harwood 
11.8 
7-1 
6.1 
5.5 
7.9 
43.6 
Prai rie Green 
28.4 
9.2 
3.0 
8.0 
8.2 
2.5 
Mean 
19.2 
6.5 
4.3 
5.0 
6.9 
38.5 
^Oue to unusually poor counting conditions, the 3 highest counts per 
stop were used in computing the average number of cock calls per area. 
Ecology and Management of Sguirrels - W-66-R 
C. M. Nixon, 
L. P. Hansen 
Many researchers have suggested that a close tie exists between fall mast 
supplies and the demography of tree squirrels, although most evidence for this 
is anecdotal. Fox squirrels heavily utilize mast during autumn and cache 
seeds for use during other times of the year. Since mast abundance fluctuates 
tremendously from year to year, it might be expected that a demographic response 
to poor or good food supplies would have evolved in fox squirrels. 
As part of the nest box study near Danville (see previous newsletters), we 
measured mast production each fall on the 2 study sites. Production of soun 
seed (Kg/ha) was calculated for each species appearing in the mast samplers. 
We trapped squirrels concurrently with mast sampling. 
Densities of fox squirrels, reproductive rates, and survival rates differed 
considerably among years; however, correlations between each of these demographic 
parameters and mast production (black oak, white oak, hickories, and total mast) 
were not significant (p *.05). The 2 study plots were vegetat.onally diverse 
and a complete mast failure never occurred during the study period. Apparently 
fox squirrels on the study plots were never seriously stressed by food shortages. 
This species is an opportunistic feeder and utilizes the most avallable food 
source. We do not say that mast is not important. In less diverse woodlots 
or when late spring frost seriously reduces total mast abundance, we might 
expect demographic consequences. Such consequences have been documented for 
gray squirrels. During an average year, however, fox squirrels do not seem to 
be affected by the abundance or shortage of mast. 
In next month's newsletter we will discuss other factors that may influence 
reproduction and survival in fox squirrels. 
Responses of Prairie Chickens to Habitat ManipuIation -W-66-R R.L. Westemeier 
Ninety-three percent of Illinois' remaining prairie chickens are located 
either on or near the nest sanctuaries—now totaling 1,001 acres in Jasper 
County and 640 acres in Marion County. Because of this limited acreage and the 
dim likelihood of adding much additional land to the sanctuary system, each of 
the 12 sanctuary units should be developed to its fullest potential. The goal 
