Vol. 20, No. 1 
Page 2 
B. 
C. 
D. 
E. 
F. 
Nests hatched on roadsides per section 
11-9 
9.3 
2.0 
3.6 
Nests hatched on roadsides (per section) 
if no early mowing had occurred 
(AX 100 r B) 
12.8 
12.1 
2.7 
4.7 
Additional nests hatched on roadsides 
(per section) if no early mowing had 
occurred (C — B) 
0.9 
2.8 
0.7 
0.9 
Average clutch size per nest hatched on 
roadsides 
7.4 
7-9 
3.5 
7.3 
Additional chicks hatched on roadsides 
(per section) if no early mowing had 
occurred (D X E) 
6.7 
22.1 
6.0 
6.6 
- From MWRL 19(12), Table 2. 
Ecoloqy and Management of Squirrels C. M. Nixon, 
-- Havera 
In the last monthly newsletter (MWRL 19(12);2—3), we discussed the rates 
of capture for various sex- and age-classes of fox squirrels captured in 
nest boxes during winter. We captured about equal numbers of adult males, 
proportionately fewer adult females, and proportionately more juveniles in 
nest boxes than were present in the squirrel population, as revealed by live- 
trapping. Nest boxes may be considered surplus denning sites (compared with 
natural dens and leaf nests) to be used more by subordinate squirrels than by 
the socially dominant adult squirrels. 
Do nest boxes really benefit individual squirrels? Nest boxes should 
provide better protection from predators and inclement weather than leaf nests. 
Thus far, our study shows that juveniles benefit more than adults from use of 
nest boxes. We found that fa 11-to-spring survival of juveniles using nest 
boxes (14/19 = 73*7 percent) was much higher than survival of juveniles that 
did not use boxes ( 11/25 = 44 percent) during the winters of 1972-73, 1973-74, 
and 1975-76. Fa 11 -to-spring survival of adult males was similar whether they 
used nest boxes (13/16 = 31.3 percent) or used natural dens or leaf nests 
(38/49 = 77.6 percent). Fa 11-to-spring survival of adult females was also 
similar, 70.0 percent (7/10) for those using nest boxes and 82.7 percent 
(43/52) for those not using boxes. 
Nest boxes are usually vacated by adult squirrels each summer, when they 
seek the cooler, less parasitized leaf nests for shelter. Thus, unoccupied 
nest boxes are usually available each fall for use by juveniles, who would 
otherwise have to use leaf nests or disperse from the area. The favored tree 
cavities are probably nearly all usurped by adult squirrels each year. 
