September, 1945 



Browx & Yeager: Squirrels ix Illinois 



507 





Fig. 27. — Osage orange fruits provide food for fox squirrels from late summer through the 

 winter. Cobs under the tree indicate extensive use of corn from an adjoining field. 



and June, mulberries apparently rank 

 first; and, during the early summer, corn 

 in the milk stage is probably highest in 

 palatability rating, at least for fox squir- 

 rels. 



Because of the well-known adaptability 

 of fox squirrels to open timber and agri- 

 cultural habitats, this species makes greater 

 use of farm crops than gray squirrels. Of 

 farm-crop foods, corn is of outstanding 

 importance, but wheat, soybeans, oats, 

 apples and other crops are popular. Field 

 crops adjoining woodlots or other timbered 

 areas are used more than those in fields 

 some distance from such areas. Corn is 

 the only cultivated crop used to any con- 

 siderable extent by gray squirrels in Illi- 

 nois, and this only where fields adjoin 

 woodland suitable to their requirements. 

 Isolated nut trees, hazel clumps or bramble 

 patches are ordinarily monopolized by fox 

 squirrels. 



Failure of any important mast species 

 tends to hasten and increase the use of the 

 species that produce. In 1941, the hick- 

 ory nut crop was heavy over much of 

 Illinois. Squirrels in the central zone 

 began to use the nuts by mid August, and 

 black walnuts were left untouched until 

 early September. In 1942, hickory mast 

 was scarce in many localities. The small 

 supply was soon exhausted, and in August 



the squirrels shifted to walnuts, which 

 were still green. Squirrels inhabiting 

 areas short of summer foods, of which 

 heavily grazed woodland is probably the 

 best Illinois example, are often driven to 

 use immature acorns. In the black oak 

 stands in Mason and Cass counties, where 

 the ground cover is mainly grasses, seed- 

 lings and second-growth sprouts, immature 

 acorns were taken by the fox squirrels resi- 

 dent there as early as July 15. 



Fox squirrels were found to be more 

 tolerant of limited variety in diet than 

 gray squirrels, and on many areas having 

 only one or a very few staple foods it was 



Fig. 28. — Svveetgum "hails" stored by a gray 

 squirrel, Horse Shoe Lake (Jame Refuge, Al- 

 exander County, Illinois, December, 1940. 

 This is the only instance of cavity storage 

 noted in tree squirrels in 4 years of field work. 



