California mammals

Salt Marsh Harvest Mouse in California

Reithrodontomys raviventris

Native to California S3 Vulnerable in California

Not listed as nonindigenous in California by USGS NAS; native to its California range.

IUCN Red List status

EN – Endangered

Very high risk of extinction in the wild.

Photo: Annette Herz · CC BY 4.0Salt Marsh Harvest Mouse (Reithrodontomys raviventris)Photo: LJ Moore-McClelland · CC BY 4.0Salt Marsh Harvest Mouse (Reithrodontomys raviventris)Photo: Bjorn Erickson/USFWS · Public domainLive salt marsh harvest mouse close-up, alert and facing cameraPhoto: M. Bias, US Department of the Interior · Public domainLive salt marsh harvest mouse balanced on a plant stem above open marshland

Salt Marsh Harvest Mouse in California, by the numbers

Rare in California 166th most recorded of 241 mammals logged in California

1,047 occurrence records

39 with iNaturalist photos

Records from 2000–2026.

1,047 total records count every California occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300; the monthly chart covers the 1,045 records with a full observation date.

When to look for the Salt Marsh Harvest Mouse in California

Most sightings fall in February.

1,045 California occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence.

Monthly California records (table)

Month	Records
January	62
February	206
March	71
April	105
May	53
June	89
July	79
August	92
September	29
October	141
November	33
December	85

Monthly salt marsh harvest mouse occurrence records (iNaturalist and GBIF) in California, 2000–2026.

Seasonality

Year-round in California, with recorded sightings peaking in February, with a smaller rise in October.

Occurrence map

Where Salt Marsh Harvest Mouse has been recorded in California

300 records mapped · zoom and drag to explore

300 California records mapped

Notable places to look

Park, forest, or monument	iNaturalist records
Corte Madera Marsh Ecological Reserve	22
Peytonia Slough Ecological Reserve	1
Eden Landing Ecological Reserve	1

Protected places with the most salt marsh harvest mouse sightings, from the USGS Protected Areas Database plus named mountain ranges, good spots to look, not a full breakdown, so they don't sum to the total.

Where it's recorded in California

County	Records
Contra Costa County	459
Sonoma County	139
Solano County	103
Marin County	86
Santa Clara County	75
San Mateo County	75
Alameda County	72
Napa County	8
Other localities	30

The complete county distribution, spread across 8 California counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Salt marsh harvest mouse records occur in every month of the California series, but the pattern is uneven. February has the largest total, followed by October, while September and November are the quietest months. Those peaks may reflect the timing of targeted surveys as much as changes in mouse activity.

Don Edwards San Francisco Bay National Wildlife Refuge is one of three suggested refuge settings, alongside Sonny Bono Salton Sea and the Klamath Basin refuges, but the file supplies no place-level counts to compare them. NatureServe ranks the species S3, vulnerable, in California and G1 globally. Those conservation ranks carry more meaning than its position in a record-count table, which is not a measure of abundance.

Occurrence data from iNaturalist and GBIF.

Full species profile Salt Marsh Harvest Mouse Reithrodontomys raviventris Size 7.6 cm3 in Weight 11 g0.4 oz Lifespan Up to 2.6 yr View the full profile

More mammals in California in the atlas

Data & sources

The data and visualizations on this page draw on these open sources:

GBIFCC-BY 4.0occurrence records behind the range map, elevation, and record counts
iNaturalistCC0 / CC-BY / CC-BY-SAobservations, photos, and audio recordings
NatureServe ExplorerCC-BYthe state conservation rank
IUCN Red Listattributed factthe global conservation status
USGS NASpublic domainnative / introduced status
Natural Earthpublic domainthe relief basemap
USFSpublic domainnational-forest boundaries
USGS Protected Areas Databasepublic domainthe named parks, forests, and refuges behind "notable places to look"