September, 1945 Brown & Yeager: Squirrels in Illinois 



505 



climbing buckwheat, burdock and Ameri- 

 can lotus seeds. In several instances it 

 was found that acorns that had fallen 

 in water were eaten 3 or 4 months later, 

 after the winter drawdown, on areas af- 

 fected by navigation dams on the Missis- 

 sippi River, fig. 25. Many other seeds are 

 undoubtedly eaten during the period of 

 scarcity ; and various writers have reported 

 greater use of animal foods, particularly 

 insects, during the late winter and spring 

 than at any other time. 



Food Preferences 



The acorns of every species of oak oc- 

 curring in Illinois appear to be used by 

 squirrels, but because of their abundance 

 and wide distribution those of pin oak 

 {Quercus palustris) , white oak {Q. alba) 

 and black oak {Q. velutina) are the most 

 important food sources. The acorns of 

 bur oak {Q. macrocarpa), shingle oak 

 {Q. imbricaria) , chinquapin oak {Q. 

 Muhlenbergii) , swamp white oak {Q. 

 bicolor) and others are taken where they 

 occur. According to Allen (1943) red 

 oak {Q. borealis maxima) acorns are 

 bitter and, in Michigan at least, appear to 

 be used less than the fruit of most oaks. 

 Of the hickories, the shagbark (Carya 

 ovata) , both because of its statewide dis- 



tribution and tendency to fruit, is easily 

 first in use among Illinois squirrels. Nuts 

 of the small pignut (C. oralis), occurring 

 most commonly in east-central and south- 

 ern Illinois, were found to be eaten avidly 

 by both fox and gray squirrels, fig. 26. 

 The mockernut (C. alba), pignut (C. 

 glabra), big shellbark (C laciniosa) and 

 most other Illinois hickories are of only 

 secondary importance, partly because they 

 are less common than the shagbark and 

 also, perhaps, because they are thicker 

 shelled and therefore more difficult for 

 squirrels to open than are the thin-shelled 

 species. The bitternut {C. cordiformis) , 

 although thin-shelled, is both bitter in taste 

 and small in size, but appears to be uti- 

 lized. Pecan (C. pecan) is eagerly taken 

 wherever it occurs and represents the 

 most important mast species in the central 

 and lower Illinois River bottomlands and 

 in some southern Illinois localities. 



Squirrels show definite preferences when 

 several foods are abundant at one time. 

 During "mast years," when a dozen or 

 more staple or substaple foods, including 

 hickory nuts, walnuts, pecans, acorns, 

 beechnuts, hazelnuts and corn, may be 

 available in quantity from late August 

 through September, hickory nuts (shag- 

 bark and the small pignut) seem to rank 

 first in preference with both fox and gray 



Fig. 25.— After winter drawdown on area affected by Mississippi River navigation dam, 

 squirrels foraged under ice for pin oak acorns that had lain in water since the previous fall. 

 Carroll County, January, 1941. 



