SUMMARY

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.