The prairie vole makes a tortuous network of paths through the grass and
honeycombs the topsoil with its tunnels. The underground passages lead
to nests or to chambers where food is sometimes stored. The runways
through the grass are 40 to 50 mm. wide, and usually lie slightly below
the surface of the ground. By using the same path repeatedly, the voles
create little ruts in which they run. The bottom of the runways are bare
soil or are covered with only a thin layer of trampled grass. Cotton
rats, on the other hand, apparently do not use their runs over long
periods, for they are not well-beaten runways, but are made merely by
parting the grass and not by trampling it down or cutting it off. Voles
were trapped in runways of the cotton rats, but no cotton rat was caught
in a typical runway of a vole.
The burrows of the prairie vole are 40 to 50 mm. in diameter, and the
shallowest part is usually 50 to 100 mm. below the surface of the
ground. Burrows leading to nests or food chambers may descend deeper
than the others. Some prairie voles were trapped in tunnels of the
common mole (_Scalopus aquaticus_). The voles make their own burrows,
and are especially active at this task when a hard rain has loosened the
previously hard, dry soil. The rain in the first two weeks of October,
1945, made the soil much more friable than it had been at the beginning
of the month, and the voles took advantage of the favorable opportunity
to construct many new burrows. In October, particles of soil were packed
beneath the toenails of many specimens.
In this time fifteen nests were found. They were 6 to 18 inches below
the surface of the ground, and two tunnels led from each nest to the
surface runway. The nest cavities were spheroidal, and measured 150 to
200 mm. horizontally, and 80 to 100 mm. vertically. The floors were
slightly concave and were covered with loose dirt and a mixture of dried
grass and one or two leaves. The remainder of the cavity was filled with
the dry grass of which the nest was composed. Criddle (1926) stated that
at Treesbank, Manitoba, this vole makes its nests in the burrow systems
of the pocket gopher (_Thomomys talpoides_); and Kennicott (1857:98)
found nests of the prairie vole in old ant hills.
Each of two nests that had been recently occupied was placed in a
Berlese funnel, and in this way the arthropod fauna of the nests was
collected. The most common arthropods in the nests were mites
(parasitic, predaceous, and free-living) and springtails. Sowbugs,
centipedes, spiders, and fleas were also present. Of these arthropods,
the laelaptid mites, one kind of tick, and one kind of flea have a
direct relationship with the vole. These parasites are the same species
which are found on the vole itself. The mites were _Eulaelaps
stabularis_ (Koch) and _Atricholaelaps glasgowi_ (Ewing). One adult
tick, _Ixodes sculptus_ Newman, was in one nest. The fleas, about a
dozen in each nest, were _Ctenophthalmus pseudagyrtes_ Baker, the flea
most frequently found on the prairie vole.