Wisconsin mammals

Least Weasel in Wisconsin

Mustela nivalis

Native to Wisconsin S4 Apparently Secure 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

LC – Least Concern

Widespread and abundant; not at risk.

Least Weasel in Wisconsin, by the numbers

Rare in Wisconsin 53rd most recorded of 75 mammals logged in Wisconsin

23 occurrence records
14 with iNaturalist photos
Jun 22, 2026 Last seen in Wisconsin

Records from 2000–2026.

When to look for the Least Weasel in Wisconsin

Most sightings fall in September.

23 Wisconsin 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 Wisconsin records (table)
MonthRecords
January0
February2
March3
April2
May0
June4
July2
August2
September5
October0
November1
December2

Monthly least weasel occurrence records (iNaturalist and GBIF) in Wisconsin, 2000–2026.

Seasonality

Year-round in Wisconsin, with recorded sightings peaking in September, with a smaller rise in March and June.

Occurrence map

Where Least Weasel has been recorded in Wisconsin

23 records mapped · zoom and drag to explore

23 Wisconsin records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Chiwaukee Prairie State Natural Area 1

Protected places with the most least weasel 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 5
Waukesha County 2
Sauk County 2
Waushara County 2
St. Croix County 1
Ozaukee County 1
Jefferson County 1
Adams County 1
Brown County 1
Racine County 1
Iowa County 1
Lafayette County 1
4 other counties 4

The complete county distribution, spread across 16 Wisconsin counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Wisconsin’s 23 records fit open, prey-rich settings such as Horicon’s marsh margins, Kettle Moraine fields, and southern prairie remnants, but they are too thin to define a reliable seasonal pattern. Scattered detections across winter and the growing season are consistent with a year-round resident that is usually concealed in dense ground cover or small-mammal burrows.

Only 14 records come from iNaturalist, and these are encounters rather than a Least Weasel abundance estimate. Incidental trapping, predator remains, snow tracks, and rare chance sightings dominate detection, making observer method far more visible in the map than the underlying population.

Occurrence data from iNaturalist and GBIF.

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"