Caches of seeds and underground parts of plants are stored in
subterranean chambers. One lot of food was found stored on the surface
of the ground. Four times, piles of seeds in runways indicated the
species of plants which the voles were storing.
One underground cache was found on May 27, 1946, on the University
campus, by John Evans, Richard Edgar, and the writer. This cache was in
a large chamber in a tunnel system of the prairie vole, on an
east-facing hillside of walnut trees, catalpas, and Kentucky coffee
trees. The oval chamber was 250 mm. wide, 400 mm. long, and 200 mm.
high. The roof, at its highest point, was 30 mm. below the surface of
the ground. There were two entrances to the cavity, both on the downhill
side. The cache consisted of eight quarts of seeds (approximately 2,800)
of the Kentucky coffee tree (_Gymnocladus dioica_). The seeds were
packed with earth and all were well preserved. The site of this cache
was in an area which was shaded by a small coffee tree. A seed of this
tree is spheroidal, measures 17 mm. in width, and weighs 2 grams.
Several times in the fall of 1945, in the above-mentioned grove, the
writer found pods of the coffee tree lying in the runs of the voles.
These pods were sometimes entire, but more often they had been gnawed;
frequently only part of a pod remained, indicating that the voles were
storing or feeding upon the seeds, although the possibility that the
mice were storing food did not occur to the writer at the time. Three
times, seeds of other plants were found piled at the entrances of the
burrows of voles. Twice these piles consisted of from 50 to 70 seeds of
the common dandelion (_Taraxacum officinale_). The third pile was
composed of 20 seeds of the giant ragweed (_Ambrosia trifida_).
A pasture of Canadian bluegrass (_Poa compressa_), wild millet
(_Echinochloa crusgalli_), sedges (_Scirpus_ spp.), and clover
(_Trifolium_ sp.) in Atchison County, Kansas, was examined in November,
1945. This area was the home of a dense population of prairie voles.
Wherever a path of the voles crossed a deep imprint of a horse's hoof,
there was a collection of cuttings from the horizontal stems of the
clover which bordered the runways. Some of the cuttings may have been
made by lemming mice (_Synaptomys cooperi_) which were also common in
the area.
Several kinds of voles store food. Bailey (1920) wrote of the caches of
_Microtus pennsylvanicus_ in North Dakota, where, in one locality, this
vole was known as the bean mouse. He stated that the Indians dug up
beans (_Falcata comosa_) and the tubers of the Jerusalem artichoke
(_Helianthus tuberosus_) which the voles had stored. Lantz (1907:17)
found a cache of the roots of wild morning glory (_Convolvulus sepium_)
laid away by _Microtus pennsylvanicus_. Nelson (1893:140) wrote that, as
winter approached, _Microtus operarius_ gathered small bulbous roots,
sometimes storing a peck or more in a single cavity. Fisher (1945) in
Missouri found a gallon of the fruits of the horse nettle (_Solanum
carolinense_) stored in a hollow stump by the prairie vole. Kennicott
(1857:99) found five or six quarts of roots of two species of
spike-flower (_Liatrus_), _Helianthus_, and various grasses among the
winter provisions of the prairie vole in Illinois.