Vo 1. 20, No. 7 
Page 2 
Table 1. Number of cocks observed per mile of driving along standardized 
routes in the SSA and FCMU, Apri1-Hay 1970-77- 
1970 1971 
1972 
1973 
1974 1975 
1976 
1977 
SSA 
0.497 1•669 
1.919 
2.825 
2.303 0.925 
1.233 
0.303 
FCMU 
0.974 1.425 
0.395 
1.235 
1.219 0.570 
1.174 
0.223 
Table 2. 
Number of cock 
calls per 
2-minute 
stop averaged for 
the five 
morn i ngs 
of highest counts. 
SSA—/ 
Pra i rie 
FCMU 
Anchor 
Harwood 
G reen 
1976 
22.9 
13-7 
20.0 
11-5 
23.4 
1977 
7.6 
2.3 
5-7 
7-1 
3.2 
Percent 
71.6 
67.6 
decline 67 .1 
79-6 
38.3 
a/ 
Counts were made 
on two mornings in 
I 970 and four mornings in 
1977. 
Ecoloov and Management of Squirrels C. M. Nixon, 
-^ ‘ L. P. Hansen 
Adult female fox squirrels usually conceive at least once during a 
breeding year (December-September). We have examined adult female fox squirrels 
on two study areas in Vermilion County, Illinois, for the past 6 years. In 
1971 (N == 12), 1972 (N = 10), 1975 (N = 14), and 1976 (N =- 12), all adult 
females examined during spring and fall had conceived at least ones. In 1973; 
3 of IS adults examined did not breed during the breeding year. In 1974, 3 
of 17 did not breed. We feel that the lower breeding rate in 1973 and 1974 
was due to the effects of the poor mast crop of 1973* The effects of the 
reduced tree seed crop were still evident as late as June-July 1974, when 
summer litters are usually conceived, because those females that did not con¬ 
ceive during the 1973-74 winter period also skipped the 1974 summer breeding 
period. 
