220 Fretp Museum or Naturat History — Zoétocy, Vor. XI. 
Prairie Meadow Mouse or Prairie Vole (Microtus ochrogaster). 
opening on one side. This burrow and nest are occupied in winter, 
and in it at least the first litter of young is produced in the spring; but, 
in the summer and fall, these meadow-mice may be found in similar 
nests in the grass above ground, in which the young are often, if not 
usually, brought forth. Nests formed under the snow in winter are 
also occupied by them. From the burrows, innumerable runways 
traverse the neighborhood, intersecting those from other burrows, thus 
forming a complete net-work so that often scarcely a square yard can 
be found in an acre not crossed by one or more of these tracks. The 
runways of one pair may sometimes be traced five or ten rods on every 
side. These roads are not only formed for use in winter, when the 
ground is covered with snow, but are also employed as highways in 
summer. They are made above ground by pressing down and gnawing 
off the grass, and the earth is often worn quite smooth and bare in those 
most used. The inhabitants can travel easily along them at all times, 
in search of food, being well concealed by the overarching grass. In 
winter, these paths are formed on the ground, under the snow, as well 
as in the grass. The mice do not inhabit prairie pastures, where the 
grass is eaten close and affords them no cover. 
“Upon examining, in November, the burrow of a pair of these 
meadow-mice, situated on the wild prairie, I found the excavation to 
have been recently enlarged. The nest was placed near the centre of 
