716 



THE MONTHLY BULLETIN. 



tarian of all the ground squirrels. With the opening of the season 

 the squirrel lives largely upon green succulent vegetation. This diet 

 continues through the season of active plant growth. When the vege- 

 tation begins to ripen his attention is turned to the more fat-producing 

 seed products of grain and plants, and by the time for the beginning of 

 aestivation the animal has become enormously fat. 



Like many other rodents, an occasional feast of flesh appears to be 

 necessary even though it be secured by cannibalistic methods. 



Fig. 39. A brood of young, wild squirrels. The average brood for this species 

 is five. This picture represents a vertical section showing the brood nest which is 

 made of wild grass or grain straw and lined with finely shredded material of the 

 same kind. 



Stomach analysis made during these investigations from squirrels 

 shot in the fields at various times of the day and different vegetation 

 habitats and state geographic ranges show the following conditions: 



Of 43 stomachs examined, 100 per cent contained vegetable matter; 

 86 per cent contained vegetable matter entirely; 2 per cent contained 

 traces of mammals ; 13.9 per cent contained traces of insect remains. 



ESTIVATION AND HIBERNATION. 



In the preparation of this long period of inactivity, the squirrel has 

 become enormously fat. Not only has he stored up enough of this fat 

 reserve to carry him through his long night of seclusion and darkness, 

 but past it, and the adverse conditions of spring, and well on into the 

 breeding season. 



As the season of green vegetation gives way to one of parched dessi- 

 cation, he instinctively seeks a place of seclusion, becomes timid and 

 shy, and is seen only occasionally during the last two weeks of his 

 activity. He avoids prolonged exposure to noonday heat, which is 

 fatal to him now. He sleeps long intervals at a time, partakes very 

 sparingly of food, and when his alimentary tract is largely free from 



124 



