176 Order RODENTIA 



breast and anterior part of the belly, are washed with yellow 

 or rust. The tail is short, and the under side of it is somewhat 

 lighter in color than the upper side. Each hind foot has five pads 

 or tubercles. The female has three pairs of mammary glands. 



Length measurements: head and body 3}i—^% inches (99-117 

 mm.); tail 1-1^ inches (26-36 mm.) ; over-all 4J^-6 inches 

 (125-153 mm.) ; hind foot about ^ inch (16-20 mm.). 



The skull of this vole resembles that of the meadow vole 

 except that each of the last upper molars has four enamel 

 triangles or loops, fig. 74e, instead of six. Dental formula: 

 I 1/1, C 0/0, Pm 0/0, M 3/3. 



The prairie vole can be distinguished from the meadow vole 

 by the following characteristics: rusty or yellowish wash on 

 under parts rather than silvery, each of the last upper molars 

 with four rather than five or six triangles, each hind foot with 

 five rather than six pads, length of tail usually 35 mm. or less 

 rather than over 35 mm., and three pairs of mammae rather 

 than four. 



Life History. — ^The prairie vole lives in a variety of grassy 

 places throughout most of Illinois. In the grassy shoulders of 

 roads, grassy pastures that are not heavily grazed, clover fields, 

 grassy forest edges, and lush meadows, several prairie voles will 

 usually be found in each acre. Their surface runways, figs. 2 

 and 14, about the diameter of a garden hose, can be found by 

 parting the grass. These lead eventually to holes which open 

 into complex underground burrow systems. A small plot about 

 16 feet square may have as many as 160 feet of surface runs 

 and 10 to 40 feet of underground burrows. The prairie vole 

 obtains grasses, seeds, and various herbs for food from along 

 surface runways. It finds refuge, feeds on roots, and nests in 

 the underground burrows. 



Storage chambers for food, fig. 2, and usually the nest of the 

 prairie vole are located in an enlarged portion of an under- 

 ground burrow. The nest consists of grass — ^in some cases the 

 equivalent of several pints of it. If the grass in which this vole 

 lives is very dense and tall, the nest may be placed aboveground 

 among the roots of the grass. Young are produced throughout 

 most of the year except in the coldest winter months. There 

 are three to six young in each litter. The young develop as rap- 

 idly as do those of the meadow vole. A female of the prairie 

 vole is sexually mature when only 3 or 4 weeks old. 



