The Western harvest mouse is the smallest sigmodontine rodent in Oregon. It occurs east of the Cascade Range, except it is absent from the Blue and Wallowa mountains; it also occurs in the southern parts of Josephine and Jackson counties west of the Cascades.

The Western harvest mouse commonly uses runways. It is active nocturnally with its greatest activity between sunset and sunrise. They spend periods of inactivity in ball-shaped nests constructed on the surface of the ground; nests are sometimes placed beneath shrubs or debris.

Photo by J. N. Stuart, Flickr