September, 1945 



Brown & Yeager: Squirrels ix Illinois 



503 



Fig. 23. — Elm (left) and maple buds and flowers offer the first squirrel food jiroduced each 



year. 



oak occurred, fig. 22. Only fox squirrels 

 inhabited this locality, and during years 

 of poor acorn crops they would be forced 

 to depend mainly on residues of corn, rye 

 and other grains, and such natural foods 

 as wild grapes, bittersweet and miscel- 

 laneous seeds and herbage. 



In practically every section of Illinois, 

 a general failure of oak mast, and in some 

 sections, especially in southern and south- 

 w'estern localities, failure of wild pecans 

 in the bottoms and hickories and black 

 walnuts on the uplands might create un- 

 fortunate food contingencies during the 

 late winter and early spring. That serious 

 food shortages did not prevail in many in- 

 stances in 1940—1942 is indicated by the 

 good to excellent condition of the several 

 hundred squirrels examined, some of which 

 were collected during every month of the 

 first 2 years of study. 



The nature of the food studies made in 

 this investigation did not permit deter- 

 mination of either the number or impor- 

 tance of animal foods taken by squirrels in 

 Illinois. Numerous writers, however, 

 have called attention to the inclusion of 

 insects and other animal forms in the 

 dietary. Davis (1907. 1924) reported 

 the destruction of acorn weevil larvae 

 {Balaninus) and oak apple galls {Ain- 

 phibolips confluens) by gray squirrels. 

 These animals were observed by Hamilton 



( 1943) to feed on caterpillars of the half- 

 wing geometer {Phiyalia titea). Good- 

 rum (1940) found that in Texas over 3.5 

 per cent of the food of gray squirrels con- 

 sisted of insects, mainly lepidopterous lar- 

 vae. He also presented limited evidence 

 to show that animal food is necessary to 

 successful breeding. Both fox and gray 

 squirrels are said by Seton (1928) to use 

 insects and other animal matter. The 

 evidence is general that animal life, par- 

 ticularly insects, constitutes a small but 

 more or less important food source for tree 

 squirrels. 



Brooks (1922) reported the use of 

 chestnut bark and other tree bark by gray 

 squirrels in West Virginia, and Allen 

 ( 1943) reported use of maple bark by fox 

 squirrels in Michigan. 'I'he use of bark 

 by fox squirrels was observed by the junior 

 author in Coles County, Illinois. 



The effect of lumbering, fire and graz- 

 ing on squirrel food sources is discussed 

 in other sections. 



Food Succession 



Succession in the use of foods by squir- 

 rels is somewhat distinct, the Illinois study 

 showed, and the order of succession in this 

 state is approximately the same in both 

 species. The first foods of the late winter 

 or spring season are the buds and flowers 



