September, 1945 



Brown & Yeager: Squirrels ix Illinois 



497 



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Fifj. 21. — This Piatt County woodlot of mixed hardwoods, including hickory, black oak, 

 white oak, walnut, elm and soft maple, offers staple foods at all seasons. A nearby cornfield and 

 an Osage orange hedge supplement this food supply. The mature trees contain an ample 

 number of cavities. These characteristics probably represent the optimum in fox squirrel habitat. 



cics. Information peculiar to either spe- 

 cies is detailed separately. 



Food Sources 



In table 22, 76 species or groups of 

 squirrel food plants are tabulated. In- 

 cluded are 56 trees and shrubs, 2 groups 

 of vines, 4 brambles, 6 wild herbs, 7 cul- 

 tivated crops and various fungi. The list 

 is, of course, incomplete; the writers are 

 certain that other plants, particularly 

 herbs, are taken in small amounts. The 

 unlisted foods, however, are of little sig- 

 nificance in the squirrel dietary. 



Although many items are listed in table 

 22, the important staple food sources of 

 Illinois squirrels comprise only a half 

 dozen plant groups. There are the hick- 

 ories, including pecan, and the oaks, wal- 

 nuts, elms, mulberry and field corn. An 

 imposing list of other foods ma\' be im- 

 portant locally or seasonally. E.xamples 

 are Osage orange and wild grapes. Boul- 

 ware ( 1941 ) reported local use of eucalyp- 

 tus by fox squirrels in California, and 

 Dambach (1942) similar use of hawthorn 



{Cratae(/us mollis) by gra\' squirrels in 

 Ohio. Woods (1941) reported that a 

 blackberry patch, wild plum thicket or cul- 

 tivated orchard may furnish the bulk of the 

 food for one or a few squirrels during the 

 few weeks when fruits of such plantings 

 are available. However, no matter how 

 varied and abundant auxiliary seasonal 

 foods may be, most wild squirrels arc 

 forced to rely for much of the year on one 

 or more of the staples listed. An environ- 

 ment without a \ ariety of staples may be of 

 little value, and may actually be uninhab- 

 itable, except when auxiliary foods prevail. 

 Common examples of such a deficient en- 

 vironment are river-bottom forests of pure 

 elm-maple or extensive cottonwood-willow 

 flats, even those bordering cornfields. 



From the standpoint of food, the impor- 

 tance of mixed stands in squirrel habitats 

 is clearly apparent, fig. 21. I his factor 

 is discussed by Goodrum (1938). Most 

 of the original forests were of suitable 

 composition, especially those of hardwoods 

 or mixtures of hardwoods and conifers. 

 Most of the larger natural stands now- 

 present in Illinois meet the staple food 



