Western harvest mice turn up in California’s grassy edges and wetland margins from the Salton Sea to the Klamath Basin and San Francisco Bay. That north-to-south spread joins very different climates through one useful feature: dense low vegetation where a tiny mouse can feed and remain concealed.
March holds the most reports, with January also notably high, while records continue through every month. The winter and early-spring emphasis differs from the summer-heavy pattern of many small mammals and may reflect wet-season vegetation or survey timing. It remains a pattern in submitted observations, not evidence of a seasonal rise in population.
Full species profile
