Wyoming mammals

Western Little Brown Myotis in Wyoming

Myotis lucifugus

Native to Wyoming S5 Secure in Wyoming

Not listed as nonindigenous in Wyoming by USGS NAS; native to its Wyoming 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 Wyoming, by the numbers

Occasional in Wyoming 67th most recorded of 126 mammals logged in Wyoming

17 occurrence records
13 with iNaturalist photos
Aug 19, 2025 Last seen in Wyoming

Records from 2000–2026.

17 total records count every Wyoming occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 16; the monthly chart covers the 16 records with a full observation date.

When to look for the Western Little Brown Myotis in Wyoming

Most sightings fall in June.

16 Wyoming occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence. Based on a small number of dated records; the seasonal pattern may not be representative.

Monthly Wyoming records (table)
MonthRecords
January0
February0
March0
April0
May3
June7
July1
August4
September1
October0
November0
December0

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

Seasonality

Year-round in Wyoming, with recorded sightings peaking in June.

Occurrence map

Where Western Little Brown Myotis has been recorded in Wyoming

16 records mapped · zoom and drag to explore

16 Wyoming records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Yellowstone National Park 5
Fossil Butte National Monument 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 Wyoming

CountyRecords
Lincoln County 4
Park County 4
Teton County 3
Sheridan County 1
Albany County 1
Carbon County 1
Crook County 1
Natrona County 1
Other localities 1

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

Western little brown myotis has a thin modern Wyoming record, 17 records since 2000, and the IUCN lists the species globally Endangered due to white-nose syndrome, a fungal disease that has collapsed brown bat colonies across much of North America since the mid-2000s. Yellowstone National Park holds 5 of those records and Fossil Butte National Monument 4, and 13 of the 17 came through iNaturalist rather than survey collections.

Records run from May to September and peak at 7 in June, within the active summer foraging season before bats disperse to winter hibernacula. NatureServe still lists the species S5, Secure, in Wyoming, a reminder that state-level status and the global disease threat are two different pictures.

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 Wyoming 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"