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

Rare in California 164th most recorded of 241 mammals logged in California

648 occurrence records
23 with iNaturalist photos

Records from 2000–2026.

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

When to look for the Western Little Brown Myotis in California

Most sightings fall in August.

648 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
March9
April28
May88
June155
July84
August221
September44
October16
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 August, with a smaller rise in June.

Occurrence map

Where Western Little Brown Myotis 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
Tahoe National Forest 61
Inyo National Forest 33
Angeles National Forest 9
Lassen Volcanic National Park 8
Patrick's Point State Park 6
Eagle Lake Field Station 4
Desolation Wilderness 4
Yosemite National Park 4

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
Mono County 104
Placer County 91
Riverside County 83
San Bernardino County 62
Nevada County 47
Modoc County 42
Shasta County 29
Lake County 28
Siskiyou County 25
Humboldt County 25
Plumas County 18
Monterey County 17
18 other counties 77

The complete county distribution, spread across 30 California counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

California’s combined state files contain 666 Western Little Brown Myotis records: 23 from iNaturalist and 643 from GBIF. It ranks 166th among 243 mammals in this California record comparison, placing it in the lower third. That’s a ranking of submitted records, not a head count of animals.

The monthly series reaches its high point in August, with 10 records in the busiest month. Records appear in 9 of 12 months, so the pattern shows when sightings were documented, not when the species must be present or absent.

California accounts for about 2% of the mapped GBIF records summarized on the national Western Little Brown Myotis page. That’s a small share of the known record footprint, though differences in survey effort can strongly shape the percentage.

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"