Vol. 23, No. 12 
Page 2 
,o # 00. 
Obviously we are not returning to the extensive virgin forests of \ 
However huntable squirrel densities are common in most of the second-growth 
ESHI’of Illinois; where the gray squirrel has declined, often the fox squirrel 
has thrived. Most squirrel hunters worry little about which species is the more 
abundant. 
Although both gray and fox squirrels eat about the same foods and utilize 
tree cavities and leaf nests for shelter, they prefer different hab.tats. Gray 
squirrels are abundant in Illinois only in areas at least 20% covered by forest. 
In central and northern Illinois, gray squirrels are found in forests with large 
amounts of sugar maple, white oak, elms, and black oaks. 
In an unpastured mixed-hardwood forest in east-central Illinois, gray 
squirrels were most cormon in ravine forests with large amounts of beech and. 
sugar maple. They were also found in bottomland forests containing pecan, pin 
oak, maples, cottonwood, ashes, and sycamore. They avoided the upland forests. 
In southern Illinois, however, gray squirrels are common hn both upland 
and bottomland forests. Apparently, a mmimum amount of forest (20* of the and 
area) must be present to support gray squirrels. If 20* or more of an area is 
forested and a minimum amount of winter storable food is present, tree composition 
is not so important. 
Two other factors influence gray squirrel abundance: understory densities 
and abundance of tree cavities. All forests examined in central ^nd northern 
Illinois that harbored gray squirrels contained a we 11-developed forest understory 
and at least 3 tree cavities per acre. 
Fox squirrels are creatures of forest edge and are most abundant in the 
upland forests of Illinois. They achieve high densities in pastured old-growth 
wood lots; they are not abundant in the extensive bottomland forests of central 
and southern Illinois. 
With the decline in woodlot pasturing during the past 20 years (many 
farmers no longer keep livestock), understory densities have '"greased and fox 
squirrel densities have declined. In these unpastured woodlands fox squrre Is 
are most abundant in upland stands of oaks and hickories with a high density of 
trees and a low density of understory. They avoid the ravine forests frequented 
by gray squirrels. Breeding females frequently live close to the edge of a 
woodlot, whereas adult males are scattered throughout the uplands. 
Most forests on the public lands of Illinois can be expected to increase 
their yields of squirrels. These forests are relatively young (70 years).are 
still recovering from past abuse (fire, destructive logging, and pasturing) and 
will produce more food and shelter for squirrels as they mature. 
Although we cannot speed up succession (except for nest boxes to 
slow-to-form tree cavities), certain techniques may be used on public lands in 
Illinois to enhance one or the other species of squirrel, particularly 
management includes commercial logging. Next month we wi discuss the effects 
of commercial logging on both gray and fox squirrels in Illinois. 
