California mammals

Western Little Brown Myotis in California

Myotis lucifugus

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

EN – Endangered

Very high risk of extinction in the wild.

Little brown myotis roosting alertly on a wooden beamLittle brown myotis roosting in the corner of an attic beamLittle brown myotis roosting on painted wood sidingLittle brown myotis resting among blue spruce branches
Photo: Steph Brulot-Sawchyn · CC0Little brown myotis roosting alertly on a wooden beamPhoto: LeeAnn Latremouille · CC BY 4.0Little brown myotis roosting in the corner of an attic beamPhoto: Tom Romeo · CC BY 4.0Little brown myotis roosting on painted wood sidingPhoto: Patrick Jackson · CC BY 4.0Little brown myotis resting among blue spruce branches

Western Little Brown Myotis in California, by the numbers

Occasional in California 151st most recorded of 233 mammals logged in California

45 occurrence records
22 with iNaturalist photos

Records from 2000–2026.

When to look for the Western Little Brown Myotis in California

Most sightings fall in July to September.

45 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
January0
February1
March0
April2
May2
June6
July9
August11
September9
October3
November1
December1

Monthly western little brown myotis occurrence records (iNaturalist and GBIF) in California, 2000–2026.

Seasonality

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

Occurrence map

Where Western Little Brown Myotis has been recorded in California

45 records mapped · zoom and drag to explore

45 California records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Patrick's Point State Park 6
Hastings Natural History Reserve 1

Protected places with the most western little brown myotis 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
San Bernardino County 12
Humboldt County 10
Sonoma County 4
Butte County 3
El Dorado County 2
Shasta County 2
Riverside County 2
Mono County 2
San Mateo County 2
Tuolumne County 1
Monterey County 1
Nevada County 1
3 other counties 3

The complete county distribution, spread across 15 California counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

California has 45 western little brown myotis records from 2000 to 2026. iNaturalist holds 22 and GBIF 41, and the overlap between the two means those numbers shouldn’t be added. The total ranks the bat 151st of 233 mammals in California’s record count, which tracks documentation effort, not how many bats live here.

The records split between San Bernardino County, with 12, and the redwood coast of Humboldt County, with 10, where Patrick’s Point State Park alone accounts for 6. Sonoma, Butte, and eleven other counties fill in the rest, and Hastings Natural History Reserve in Monterey County adds a single record.

Reports climb through summer to an August high of 11 and drop sharply after September, the warm months when the bat is active and most bat surveys happen. The IUCN lists the species as Endangered globally, though NatureServe hasn’t assigned it a California rank.

Occurrence data from iNaturalist and GBIF.

Little brown myotis roosting alertly on a wooden beam
Full species profile Western Little Brown Myotis Myotis lucifugus Size 8–9.5 cm3.1–3.7 in Weight 6–13 g0.2–0.5 oz Lifespan 35 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"