Vo l. 14, No. 6 
Page 2 
the equivalent of roadsides around 16 square miles. Nearly 40 of these 
miles were graded in 1970. V/e do not yet know which segment of these 
miles would be suitable for seeding. The Superintendent indicated that 
grading is planned along approximately 20 miles of roads in the county 
each year for 10 years, and that the County Highway Department would be 
willing to cooperate with the Department of Conservation should a decision 
be made to seed these roadsides. 
3. Ecology and Management of Squirrels C. M. Nixon 
Intensive livetrapping was undertaken at Allerton Park between 
December 1970 and March 1971 to determine the breeding period for female 
fox squirrels. A total of 12 females of breeding age were each captured 
numerous times, and 11 of these experienced an estrous cycle during the 
study period. 
Breeding commenced the first week in January. The vulva of a female 
captured January 2 was swollen, indicating approaching estrus. By 
January 25, all 11 females had undergone an estrous period and were 
pregnant. The winter breeding period in 1971 was somewhat later than the 
late December-early January breeding peak found during an earlier study 
of fox squirrel breeding in central Illinois. 
The factors responsible for initiating estrus are not well defined 
for either gray or fox squirrels. Although both the winter and summer 
breeding periods for both species occur under conditions of increasing 
photoperiod (January and late May-early June), there is insufficient data 
available to prove that increasing photoperiod is the principal factor 
initiating breeding. In most years, a few females of both species will 
experience an estrous cycle in late summer when the photoperiod is 
decreasing. It is known that adverse environmental factors, such as a 
severe winter or a lack of staple foods, will often delay or eliminate 
breeding, particularly in gray squirrels. 
4. Responses of Bobwhites to Habitat Manipu1 ation J. A. Ellis, 
D. R. Vance 
Importance values (MV/RL 13(7)*2) were calculated for plants on burned 
and nonburned plots ( 19 & 6 ) in the prescribed burn zone and on plots sampled 
in 1970 that were burned in 1968 and 1970 or in 19^9 and 1970* These data 
indicated that changes in the vegetation on these plots over the 4-year 
period were not dramatic but subtle. Goldenrod (Solidago spp.) and 
lanceleaf ragweed ( Ambrosia bidentata) continued to exhibit dominance in 
1970 as in 1966. Rough buttonweed ( Diodia teres) , an important plant in 
I 966 , declined in importance during the 4 years. The reverse occurred in 
the case of partridge pea ( Cassia fasciculata ) -- not an important plant 
in 1966 -- which gained in importance value during the 4 years. The bush 
clovers ( Lespedeza striata and L. stipulacea ) maintained the same level 
of importance in 1970 as in 1966 . Another important quail food, lesser 
ragweed ( Ambrosia artemisiifolia ), exhibited a response to the prescribed 
