FROM THE INTRODUCTION The prairie vole (Microtus ochrogaster) at Lawrence, Kansas, is approximately 5-1/2 inches in length, of which the tail comprises 1-1/4 inches, and weighs approximately 1-1/2 ounces. The color on the dorsum is dark gray with a ... Read more

FROM THE INTRODUCTION The prairie vole (Microtus ochrogaster) at Lawrence, Kansas, is approximately 5-1/2 inches in length, of which the tail comprises 1-1/4 inches, and weighs approximately 1-1/2 ounces. The color on the dorsum is dark gray with a grizzled appearance from the mixture of black and fulvous on the long hairs; the venter is paler, sometimes pale fulvous or cinnamon. The animal is compactly built much as are the other microtine rodents. The short legs and short tail, small eyes and partly hidden ears, and heavy and flattened head all suggest its semifossorial mode of life. The prairie vole spends most of its time in an elaborate system of tunnels (some entirely below the ground) and in almost hidden galleries in the dense grass. Microtus ochrogaster can be separated from other voles in its geographic range by a combination of several characters. The plantar tubercles usually number five, although a few individuals with six tubercles were found at Lawrence, Kansas. Microtus pennsylvanicus, normally with six plantar tubercles, as Bole and Moulthrop (1942:156) pointed out, sometimes has only five. Therefore, the number of plantar tubercles alone is not a certain means for separating pennsylvanicus from ochrogaster. The color of the venter of ochrogaster is usually fulvous or cinnamon instead of grayish as in pennsylvanicus, but there is variation in this respect too; some prairie voles also have a grayish venter. The shorter tail of ochrogaster will assist in establishing its identity where it occurs with pennsylvanicus. The third upper molar has two closed triangles in ochrogaster and usually three in pennsylvanicus. The pelage of ochrogaster is coarse whereas pennsylvanicus has fine fur. Prairie voles may be separated from pine mice (Pitymys nemoralis and P. pinetorum) with which they are sometimes found, by the larger eyes, less rusty color, and longer tail. The Cooper lemming mouse (Synaptomys cooperi) differs from the prairie vole in having the upper incisors grooved, and in possessing a shorter tail which approximates the hind foot in length. Less