158 Order RODENTIA 



Signs. — Tracks or droppings of the western harvest mouse 

 cannot easily be differentiated trom those of other mice. A grassy 

 nest above the ground in a weedy or grassy field may be that of 

 a harvest mouse. _ 



Distribution. — In Illinois the western harvest mouse has 

 been taken in Carroll County. Elsewhere east of the Mississippi 

 River, it has been recorded from southern Wisconsin. It is 

 found in much of the United States west of the Mississippi and 

 in Mexico, fig. 88. Animals of this species in Illinois have been 

 referred to the subspecies Reithrodontomys megalotis dych> i 

 Allen. 



REITHRODONTOMYS HUMILIS (Audubon b Bochman) 

 Eastern Harvest Mouse 



Although specimens or records of this species are lacking for 

 Illinois, an eastern harvest mouse was caught recently across the 

 Ohio River near Paducah, Kentucky. Because of this proximity, 

 the species might be expected in brome-grass and savanna-like 

 habitats in extreme southeastern Illinois. 



The combination of grooved incisors and moderately long tail 

 will serve to identify the genus. Differences in their geographic 

 ranges can be used as a provisional means of distinction between 

 the eastern harvest mouse and the paler but similar western 

 harvest mouse, Reithrodontomys megalotis. 



PEROMYSCUSMANICULATUS (Wagner)* 

 Deer Mouse Prairie Deer Mouse 



Description. — The smallest Illinois Peromyscus, the deer 

 mouse, fig. 89, usually is grayish brown (rarely ochraceous) on 

 the upper parts, with a blackish area, more or less concentrated 

 in a band, down the middle of the back. The tail, except for a 

 narrow stripe of grayish brown on top, the feet, and the under 

 parts are whitish. The ears are grayish brown, margined with 

 cream or white. The hind feet are unusually small, and the tail 

 is relatively short. 



Length measurements: head and body 3fji-3i j inches (81-90 

 mm.) ; tail 1^4-2^ inches (44-60 mm.) ; over-all 5-6 inches 



*As used here, the name white-footed mouse is restricted to the species Peromyscus 

 leucopus. 



