Vol. 23, No. 1 
Page 2 
Why some juvenile fox squirrels remain close to their birthplace and others 
disperse is not known. One hypothesis is that there are genetic differences between 
individuals that cause them to be short distance or long distance dispersers. At 
least 1 investigator feels the only difference between long and short distance 
dispersers lies in their ability to procure a breeding site. If so, dispersal 
distance would relate to the level of resistance with which the juvenile meets 
aggressive action from its mother and any strange squirrels encountered during 
the early postweaning period. A study of gray squirrels in England found that 
the breeding female often tolerated her young to settle on a portion of her home 
range and to use the same feeding and shelter sites. 
Our limited data for fox squirrels indicate that at least some juveniles are 
tolerated by their mother or are aggressive enough to establish a home range 
within her home range. 
Responses of Prairie Chickens to Habitat Manipulation - W-66-R R. L. Westemeier 
A current objective of this project is to transfer the management of prairie 
chicken habitat from Survey biologists to Department of Conservation land managers. 
The most definitive plan for the preservation of prairie chickens in Illinois must 
await a comprehensive analysis of our 17 years of data on the ecology of this 
native species. Even then, questions will always arise. However, we now have 
enough knowledge and experience to diagram a workable plan for habitat management 
(Fig. 1). By controlling vegetative succession, provision is made for 5 vital 
activities in the life history of prairie chickens, i.e. nesting, roosting, 
brooding, feeding, and booming. The plan emphasizes the quality of cover for 
nesting because this component is most limiting to prairie chickens, due primarily 
to modern agriculture. The plan is implemented by sharecropping. 
The hypothetical 130-acre tract shown in Fig. 1 is subdivided into a 90-acre 
rotational unit and a 40-acre prairie unit. The 90-acre unit is subdivided into 
10 -acre fields utilizing a rotation of soybeans, wheat or oats, red clover, and 
6 age classes of mixed redtop-timothy. All fields in the 90-acre unit may be 
allowed to progress into redtop-timothy meadows depending upon the degree of 
invasion by weeds and woody sprouts. Within 10-12 years, redtop-timothy meadows 
usually require renovation. Prescribed burning of 1 of the older 10-acre sods 
may be used to provide booming grounds v.hen a plowed field, wheat field, or new 
grass seeding is not available. Brooding and feeding cover of high quality is 
provided by small grains and red clover. Basic nesting and roosting needs are 
met by redtop-timothy stands at least 1 year of age; management is by seed 
harvesting by combine in late July and early August. Typically, nesting declines 
as redtop-timothy sods age and as weed and woody-sprout invasion progresses. 
The 40-acre prairie grass unit in Fig. 1 is subdivided into 10-acre fields 
managed by (1) prescribed burning, (2) haying, (3) mowing for seed, weed control, 
or nesting enhancement, or (4) no disturbance. The location of the prairie unit 
was based mainly upon erosion susceptibility. The permanence and heaviness of the 
rhizomatous root masses of the native grasses essentially eliminate soil erosion. 
Management of prairie grass by haying and no disturbance may need to be curtailed 
