September, 1945 



Brown & Yeager: Squirrels in Illinois 



515 



largely responsible for high survival rates 

 of juveniles and of adults in winter. 



Leaf Nests 



Late summer is the period of greatest 

 nest-building activity in Illinois for both 

 fox and gray squirrels. Stoddard (1Q20) 

 indicated that the fox squirrel in Indiana 

 and Wisconsin constructs two types of leaf 

 nests, a compact one used for young-rear- 

 ing, and a larger, more loosely constructed 

 nest used as a summer retreat. Wide 

 variability in the size and shape of nests, 



in construction materials, and position in 

 trees was observed in the present study. 

 This variabilitv rendered classifving and 

 aging of nests so difficult that the writers 

 were unable to use them as a satisfactory 

 means for censusing squirrels, although a 

 general correlation seemed to exist between 

 the number of nests and the size of the 

 population. 



Squirrels in Illinois were found by the 

 writers to exhibit no clearly defined choice 

 of tree species for nest building. Perhaps 

 because they were the most abundant and 

 widely distributed tree group, oaks con- 



Fig. 36.— Box elder barked by fox squirrel, Ugie Lounty. (Photo by C. S. Walters.) 



