70 RODENTS OF IOWA 



color below white, entirely concealing the slaty undercolor; entire 

 pelage long and soft. 



Measurements. Total length, 7.00 inches; tail vertebrae, 3.00 

 inches; hind foot, 0.87 inch. 



This is the best known of the white-footed mice, since it is most 

 common in thickly populated regions of the United States, includ- 

 ing such districts in Iowa. The name "deer mouse" apparently 

 has been given this animal on account of the supposition that the 

 seasonal change in color 'corresponds to that of the Virginia deer. 

 Adult mice do not show so much seasonal difference as the deer, 

 the main difference being in juvenile and adult pelage. "While the 

 pelage of the adult mouse is almost constantly changing such change 

 is due to wear and fading, there being but a single annual molt, 

 which occurs in summer or early fall. 



Habits, Distribution, Etc. The northern white-footed mouse is 

 partial to wooded areas, although in summer it is often found in 

 pastures where old stumps and bushes occur. In no case, how- 

 ever, is it found far from woods. Sometimes old corn and small 

 grain shocks along the edges of woods are used as homes. This 

 mouse is mainly nocturnal in its habits, though occasionally it goes 

 about during the day. It wanders about freely and makes no beaten 

 runways, though undoubtedly it often utilizes those made by other 

 rodents, especially meadow mice. This form burrows very little, 

 the most ambitious undertaking in this direction usually being a 

 simple, shallow runway under a log or other object. Though liv- 

 ing largely on the ground it is to some extent arboreal and can 

 climb trees almost as well as a squirrel. 



The nests are built in or under an old hollow log or stump, in 

 some cases in a pile of brush or in bushes. Often these mice occupy 

 the deserted nests of woodpeckers or chickadees, and again they 

 may use either temporarily or permanently a bird's nest in a small 

 bush. Frank C. Pellett reports having found them living in hol- 

 low limbs in the top of a large tree. The nest is usually composed 

 of small twigs, leaves, and grass and when on the ground is reached 

 by short, underground tunnels. On April 13, 1914, near Bayfield, 

 the writer turned over a small hollow log and found a nest of this 

 form occupied by a single individual. The nest was composed en- 

 tirely of grass, and was on low land, near water in a sparsely 

 wooded area; the nearest buildings were about one mile distant. 



