Montana mammals

Western Little Brown Myotis in Montana

Myotis lucifugus

Native to Montana S2 Imperiled in Montana

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

Rare in Montana 91st most recorded of 122 mammals logged in Montana

231 occurrence records

Records from 2000–2026.

231 total records count every Montana occurrence from GBIF and iNaturalist; the monthly chart covers the 178 records with a full observation date.

When to look for the Western Little Brown Myotis in Montana

Most sightings fall in July.

178 Montana occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence.

Monthly Montana records (table)
MonthRecords
January2
February0
March0
April3
May18
June39
July79
August29
September8
October0
November0
December0

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

Seasonality

Year-round in Montana, with recorded sightings peaking in July.

Occurrence map

Where Western Little Brown Myotis has been recorded in Montana

231 records mapped · zoom and drag to explore

231 Montana records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Glacier National Park 23
Upper Missouri River Breaks National Monument 3
Lewis and Clark Caverns State Park 2
Montana University System 1
Lolo National Forest 1
Kaniksu National Forest 1
Aerial Fire Depot Other 1
Flathead Lake Biological Station 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 Montana

CountyRecords
Ravalli County 80
Glacier County 25
Beaverhead County 22
Lake County 19
Carter County 13
Flathead County 10
Gallatin County 9
Carbon County 7
Missoula County 6
Valley County 6
Teton County 5
Fergus County 4
12 other counties 25

The complete county distribution, spread across 24 Montana counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Little brown myotis carries a substantial 231-record showing in Montana, yet the species’ own seasonality field flags it as sparsely documented, an apparent mismatch that likely reflects how GBIF specimen and survey records, not seasonal photographs, make up the entire count.

Records climb sharply from May through August, peaking at 79 in July, tracking summer roost and maternity-colony surveys. NatureServe ranks the species S2, Imperiled, in Montana, and the IUCN lists it Endangered globally, both driven by white-nose syndrome, the fungal disease that has collapsed hibernating bat colonies across North America since the 2010s.

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 Montana 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"