Fig. 112. Pennsylvania meadow mouse (Microtus pennsylvanicus kincaidi), from ten miles south of Moses Lake, Washington, April 28, 1940. (Fish and Wildlife Service photo by Victor B. [Scheffer], No. 937.)
Microtus pennsylvanicus is the most common meadow mouse of the eastern United States. It ranges westward through Canada and southward in the Rocky Mountains. A number of races occur in this extensive range. In northeastern Washington the eastern meadow mouse is locally common, being confined to marshes and damp meadows. Well-used runways are made through the dense vegetation and piles of feces and blades of grass are deposited therein. A number of broods are raised in a season, for young of many different ages are taken together in midsummer.
On the Columbian Plateau this mouse lives in marshy areas about lakes and potholes. Narrow trails are constructed through the dense vegetation. It burrows in damp earth and some occupied burrows are half-full of seepage water. Cuttings found in runways show that the mice feed on a variety of plants, including sedge (Carex). In the Moses Lake area the breeding season begins in March. Embryos found March 24, 1940, varied from 4 to 7 in number. This species is cyclically abundant.
Fig. 113. Distribution of the Pennsylvania meadow mouse in Washington. A. Microtus pennsylvanicus funebris. B. Microtus pennsylvanicus kincaidi.
Microtus pennsylvanicus funebris [Dale]
Microtus pennsylvanicus modestus [Bailey], N. Amer. Fauna, 17:20, June 6, 1900.
Microtus drummondii [Bailey], N. Amer. Fauna, 17:22, June 6, 1900.