In the eleven month period, October, 1945, until August, 1946, in
northeastern Kansas, more than five hundred specimens of the prairie
vole (_Microtus ochrogaster_) were examined in the flesh; and forty
free-living voles were examined 157 times--an average of slightly less
than four times each.
There is a complete molt from juvenal to subadult pelage, and one from
subadult to adult pelage. These molts require three weeks each.
Subsequent molts are irregular and extend over longer periods of time.
This vole, in summer, inhabits areas of grass, clover, and alfalfa. In
winter, habitats with some woody growth may be sought. Twenty-two kinds
of plants were found to be used for food. Although most of these were
succulent plants, seeds and small woody stems were sometimes eaten. The
prairie vole, like some other species of _Microtus_, lays away stores of
food, usually underground; the maximum quantity found in one cache was
two gallons.
Nine other species of small mammals occur in the same habitat with the
prairie vole, and frequently use its runways. The vole makes a network
of paths through the grass, and constructs its own burrows which lead to
its nests and food stores. Each of fifteen nests found were underground.
Most, if not all, of the underground tunnels are dug when the soil is
moist, not when the soil is dry.
The commonest flea on the prairie vole is _Ctenophthalmus pseudagyrtes_;
it averages 1.9 (for subadult voles) to 3.4 (for adult voles) per
individual vole. Other fleas on this vole are _Orchopeas leucopus_,
_Orchopeas howardii_, _Nosopsyllus fasciatus_, _Epitedia wenmanni_, and
_Rectofrontia fraterna_. The two species of fleas which were actually
common on the vole (_C. pseudagyrtes_ and _O. leucopus_), parasitized
also some other small mammals which lived in the same habitat as the
vole. One species of sucking louse (_Hoplopleura acanthopus_) and two
kinds of mites (_Laelaps kochi_ and _Atricholaelaps glasgowi_) which
occur on the prairie vole in Kansas, occur also on _Microtus
californicus_ in California and on _M. pennsylvanicus_ in New York. Only
three ticks (1 _Dermacenter variabilis_ and 2 _Ixodes sculptus_) were
found on the prairie vole.
Fifty-eight gravid females had an average of 3.4 embryos. Litters at the
height of the breeding season are larger than those at the beginning and
at the end of the breeding season. Reproduction in _Microtus
ochrogaster_ ceased in December, 1945, in northeastern Kansas, and the
first evidence of reproduction in 1946 was observed in February.