[3] Western jumping mice evolved during the Pleistocene, possibly from the fossil species Zapus burti, which is known from the late Blancan.

The mouse has coarse, dark-greyish-brown fur over the upper body, with a broad yellow to red band along the flanks, and pale yellowish-white underparts.

[5] Eleven subspecies are currently recognised:[4] Western jumping mice are omnivores, with the largest part of their diet consisting of the seeds of grasses and herbs.

[4] They subsist entirely on their fat reserves while dormant, and do not cache food; a typical mouse may lose 25% of its body weight during the eight to ten months of its hibernation.

They awake once the ground temperature reaches 8 to 9.5 °C (46.4 to 49.1 °F)[8] Predators include bobcats, weasels, skunks, raccoons, snakes and birds of prey.

The mice flee predators by making a rapid series of long jumps, interspersed with short periods when they freeze in place.