[3] Many authorities consider the endangered salt marsh harvest mouse to be a subspecies, but the two are now usually treated separately.

Also similar is the salt marsh harvest mouse (R. raviventris), which has an underbelly fur that is more pinkish cinnamon to tawny.

Once temperatures reach a certain degree, the western harvest mouse goes into torpor, but scientists have yet to determine if it goes into true hibernation.

These nests can be found on the ground or under trees, logs, or plants that aid in protection from predators.

[6] The western harvest mouse is an herbivore with a diet consisting of mainly seeds and grains from various plants.

[6] In preparation for autumn and winter, the western harvest mouse stores its food along runways created throughout fields that it occupies and in underground vaults.

[5] Although its primary food source is seeds, springtime dining is augmented with new plant growth.

A nest is approximately 13 centimeters in diameter and lined with a more downy material of fibrous plants.