Wisconsin mammals

Western Little Brown Myotis in Wisconsin

Myotis lucifugus

Native to Wisconsin S2 Imperiled in Wisconsin

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

Occasional in Wisconsin 47th most recorded of 75 mammals logged in Wisconsin

130 occurrence records
30 with iNaturalist photos
May 9, 2026 Last seen in Wisconsin

Records from 2000–2026.

130 total records count every Wisconsin occurrence from GBIF and iNaturalist; the monthly chart covers the 129 records with a full observation date.

When to look for the Western Little Brown Myotis in Wisconsin

Most sightings fall in August.

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

Monthly Wisconsin records (table)
MonthRecords
January0
February2
March0
April1
May9
June12
July16
August56
September23
October7
November2
December1

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

Seasonality

Year-round in Wisconsin, with recorded sightings peaking in August.

Occurrence map

Where Western Little Brown Myotis has been recorded in Wisconsin

130 records mapped · zoom and drag to explore

129 Wisconsin records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Nicolet National Forest 2
Door County 1
Peninsula State Park 1
Apostle Islands National Lakeshore 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 Wisconsin

CountyRecords
Dane County 35
Dodge County 19
Sawyer County 13
Walworth County 8
Iron County 6
Ashland County 6
Door County 4
Vilas County 4
Portage County 4
St. Croix County 3
La Crosse County 3
Crawford County 3
14 other counties 22

The complete county distribution, spread across 26 Wisconsin counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Wisconsin Little Brown Myotis records link Door County with Chequamegon-Nicolet and other forest-and-water landscapes, where summer roosts can sit near productive lakes, streams, and wetlands. August supplies by far the largest monthly total, consistent with active maternity colonies, newly volant young, and peak summer survey effort.

Only 30 of the 130 records are from iNaturalist, while GBIF contributes 123, so structured monitoring and institutional records dominate. The records are not an abundance estimate; roost checks, hibernaculum surveys, and repeat colony observations can concentrate detections, especially for an S2, globally Endangered bat.

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 Wisconsin 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"