[2][3] While most rodents are polygamous, the California deermouse is monogamous and forms pair bonds,[4] making it a model organism for researchers studying the genetics and neurobiology of partner fidelity[5] and paternal care.

The California deermouse has very large ears, and its tail is longer than the head and body combined.

[2][8][9] Adults are large enough that they can be confused with juvenile Neotoma fuscipes, a close relative in the subfamily Neotominae.

Males are also aggressive toward one another; their fighting techniques involve jumping, avoidance, and a characteristic mewing cry.

[20] The mouse's diet consists of shrub fruits, seeds, and flowers, such as of Rhus integrifolia, Lotus scoparius, and Salvia apiana.