California mammals

American Ermine in California

Mustela erminea

Native to California

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

Mustela Erminea headMustela erminea hibernicaMustela erminea uprightAmerican ermine standing alert on a wooden beamAmerican ermine peering from a mossy den entranceAmerican ermine in white winter coat crossing an alpine talus slope
Photo: Keven Law from Los Angeles, USA · CC BY-SA 2.0Mustela Erminea headPhoto: Alastair Rae from London, United Kingdom · CC BY-SA 2.0Mustela erminea hibernicaPhoto: Steve Hillebrand, USFWS · Public domainMustela erminea uprightPhoto: Robbie Hannawacker · CC0American ermine standing alert on a wooden beamPhoto: miaow7477 · CC0American ermine peering from a mossy den entrancePhoto: Игорь Загребин · CC0American ermine in white winter coat crossing an alpine talus slope

American Ermine in California, by the numbers

Occasional in California 157th most recorded of 241 mammals logged in California

90 occurrence records

Records from 2000–2026.

When to look for the American Ermine in California

Most sightings fall in July to August.

90 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
January5
February2
March1
April4
May4
June4
July26
August26
September11
October4
November0
December3

Monthly american ermine occurrence records (iNaturalist and GBIF) in California, 2000–2026.

Seasonality

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

Occurrence map

Where American Ermine has been recorded in California

90 records mapped · zoom and drag to explore

90 California records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Yosemite National Park 10
Sequoia National Park 4
Phillip Burton Wilderness Area 3
Kings Canyon National Park 3
Point Reyes National Seashore 3
John Muir Wilderness 2
Inyo National Forest 2
Tahoe National Forest 2

Protected places with the most american ermine 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
Mono County 16
Marin County 8
Nevada County 8
Humboldt County 7
Tuolumne County 7
Mariposa County 7
El Dorado County 6
Fresno County 4
Tulare County 4
Inyo County 3
Tehama County 3
Mendocino County 3
7 other counties 14

The complete county distribution, spread across 19 California counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

American Ermine records in California fit cool conifer forest, rocky slopes, and mountain meadows.

Reports center on the Sierra Nevada high country, with records separated from California’s hot lowlands. They show where people have documented the species, and they don’t rank California’s best habitat.

Reports rise most clearly in Jul–Sep. That pattern can reflect animal movements, weather, and observer effort, so it isn’t a population count.

Occurrence data from iNaturalist and GBIF.

Mustela Erminea head
Full species profile American Ermine Mustela erminea Size 17–33 cm6.7–13 in Weight 70–260 g2.5–9.2 oz Lifespan Up to 12.5 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
  • 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"