California mammals

Fog shrew in California

Sorex sonomae

Native to California SNR Unranked in California

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

IUCN Red List status

  1. LC
  2. NT
  3. VU
  4. EN
  5. CR
  6. EW
  7. EX

LC – Least Concern

Widespread and abundant; not at risk.

Fog shrew in California, by the numbers

Rare in California 186th most recorded of 241 mammals logged in California

482 occurrence records
25 with iNaturalist photos

Records from 2000–2026.

482 total records count every California occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300.

When to look for the Fog shrew in California

Most sightings fall in July to August.

482 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)
MonthRecords
January1
February3
March5
April9
May32
June65
July106
August153
September42
October46
November9
December11

Monthly fog shrew occurrence records (iNaturalist and GBIF) in California, 2000–2026.

Seasonality

Year-round in California, with recorded sightings peaking in July–August.

Occurrence map

Where Fog shrew has been recorded in California

300 records mapped · zoom and drag to explore

300 California records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Phillip Burton Wilderness Area 14
Redwood National Park 11
Point Reyes National Seashore 11
Patrick's Point State Park 3
Trinidad State Beach 3
Six Rivers National Forest 3
Golden Gate National Recreation Area 2
Hendy Woods State Park 1

Protected places with the most fog shrew 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

CountyRecords
Humboldt County 277
Del Norte County 56
Mendocino County 49
Sonoma County 46
Marin County 30
Siskiyou County 17
Trinity County 5
San Francisco County 2

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.

Fog shrew is easy to overlook in California because its small size and hidden life produce far fewer casual reports than larger mammals. Moist soil, leaf litter, stream edges, or mountain meadows matter more than a broad state label suggests.

California’s strong rain shadow separates damp coastal and Sierra habitats from much drier interior country. Records cluster where people survey small mammals, so blank areas don’t reliably mark the edge of the animal’s range.

The California record set combines 25 research-grade community observations with 474 museum and survey records. Monthly patterns can also reflect weather and observer activity, so they shouldn’t be treated as a direct count of animals.

Occurrence data from iNaturalist and GBIF.

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"