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Illinois Natural History Survey Bulletin 



Fol. 23, Art. 5 



requirements of both fox and gray squir- 

 rels, and many woodlots, supplemented by 

 agricultural crops, particularly corn, meet 

 these requirements for fox squirrels. 



The writers found during 2 years of 

 field work only one extensive squirrel 

 habitat showing definite evidence of food 

 shortage. This was the Mississippi River 

 bottoms in Carroll County, where pin 

 oaks furnished the main squirrel fare over 

 a large area. Only fox squirrels occurred 



there, and they were somewhat under- 

 weight, mangy and otherwise in subnormal 

 condition during the late winter of 1940- 

 41. The near failure of pin oak acorns 

 on the area in 1940 is believed to have 

 been the main reason for this situation. 



At least one other area was found where 

 serious food deficiency would likely result 

 from mast failure. This was the sand 

 region of Cass and Mason counties, where 

 extensive and nearly pure stands of black 



Fig. 22. — Nearly pure black oak stand in Mason County, Illinois. During years of mast 

 failure, pronounced squirrel food shortage may exist in this type due to lack of variety in staple 

 food species. Den boxes, erected for wood ducks, are readily used by fox squirrels. 



