Vo l. 23, No. 7 
Page 2 
The reproductive intensities of yearling and adult females were positively 
correlated (r = .68, n = 7) and both were negatively related with the number of 
adults and total number of fox squirrels the previous trapping period (Table 1). 
Unfortunately, the small sample sizes hamper the statistical analyses, but of 
all comparisons made, number of fox squirrels the previous season accounted for 
the largest amount of seasonal and annual variation in reproduction. 
Juvenile survival (birth to 6 months) and adult male survival were not 
influenced by the number of adult males or females or the total number of fox 
squirrels (Table 2). Adult female survival, however, may have been negatively 
affected by adult numbers, especially males (Table 2). These data suggest that 
male and female survival may be regulated by different factors. Although not 
conclusive, these results indicate that intrinsic factors may play some role in 
population regulation of fox squirrels. Implications of this regulatory system 
to management of fox squirrels may be important, especially in programs where 
artificial means of increasing harvestable animals on an area are being considered. 
Table 1. Correlation matrix comparing reproductive intensity (percent breeding 
with arc sine transformation) and numbers of fox squirrels present the previous 
trapping period. 
Reproductive Intensity 
(% Lactating) 
Yearling Female 
Adult Female 
Number Adult Males 
-0.96 (n = 
6) 
-0.499 (n = 12) 
Number Adult Females 
-0.751 (n = 
6) 
-0.544 (n = 12) 
Total Squirrels 
-0.799 (n = 
7) 
- 0.522 (n = 12) 
Table 2. Correlation matrix 
comparing percent 
survival (arc 
sine transformation) 
and number of fox squirrels 
present (n = 12). 
Survival 
Adult Male 
Adult Female Juvenile 
Number Adult Males 
-0.295 
-0.592 
-0.168 
Number Adult Females 
-0.15 
-0.448 
-0.148 
Total Squirrels 
-0.216 
-0.225 
-0.021 
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