140 



Order RODENTIA 



is seen. Frequently this chipmunk twitches its tail in unison 

 with the call. 



Length measurements: head and body 6J4-7 inches (160-175 

 mm.) ; tail 3\4^\% inches (80-110 mm.) ; over-all about 9}/?- 

 111/4 inches (240-285 mm.); hind foot IH-U/z inches (34-38 

 mm.). Weight: about J4 pound (100 gm.). 



The skull, which is 39-42 mm. (about \y% inches) long, lacks 

 an antorbital canal and has only four cheek teeth on each side 

 of the upper jaw. Dental formula: I 1/1, C 0. Pm 1 1. 

 M 3/3. 



Life History. — The eastern chipmunk is usually unsociable 

 and shy. A chipmunk, at the approach of another of its kind, 

 may give a few flicks of its tail and then dash out suddenly to 

 chase the intruder away. This animal inhabits brushy woods. 

 fig. 1, wooded bluffs, or woods opened by lumbering activities 

 where there is an abundance of old logs and tumbled stones to 

 furnish shelter for burrows, nests, and lookout stations. It will 

 abandon closely pastured woodlands, and its absence from many 

 wooded parts of Illinois is attributed to overgrazing. 



The chipmunk is primarily a ground dweller, living in a bur- 

 row which it has dug among tree roots or beneath a log, rock, 

 or building. It may occasionally climb into trees. Its burrow 

 may be 20 feet long and have one or several storage chambers 

 in addition to the nest. It feeds chiefly on a variety of fruits 

 and seeds and on insects. In the summertime when juicy berries 

 are ripe, tell-tale stains may be seen on its cheeks. The chip- 

 munk may carry in its cheek pouches a multitude of seeds such 

 as hazelnuts, acorns, basswood fruits, oats, hickory nuts, grass 

 seeds, corn, and elm seeds to store in its chambers for the winter 

 supply of food. It does not grow excessively fat as winter ap- 



Fig. 79. — Eastern chipmunk. 



