Pennsylvania mammals

American Ermine in Pennsylvania

Mustela erminea

Native to Pennsylvania

Not listed as nonindigenous in Pennsylvania by USGS NAS; treated as native to its mapped Pennsylvania 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.

American Ermine in Pennsylvania, by the numbers

Occasional in Pennsylvania 44th most recorded of 77 mammals logged in Pennsylvania

25 occurrence records

Records from 2000–2026.

25 total records count every Pennsylvania occurrence from GBIF and iNaturalist; the monthly chart covers the 23 records with a full observation date.

When to look for the American Ermine in Pennsylvania

Most sightings fall in May to June.

23 Pennsylvania 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 Pennsylvania records (table)
MonthRecords
January1
February2
March0
April2
May6
June5
July3
August2
September1
October0
November0
December1

Monthly american ermine occurrence records (iNaturalist and GBIF) in Pennsylvania, 2000–2026.

Seasonality

Year-round in Pennsylvania, with recorded sightings peaking in May–June.

Occurrence map

Where American Ermine has been recorded in Pennsylvania

25 records mapped · zoom and drag to explore

25 Pennsylvania records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Jacobsburg State Park 1
Kinzua Bridge State Park 1
State Game Land #176 1

Protected places with the most american ermine 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 Pennsylvania

CountyRecords
Lackawanna County 2
Allegheny County 2
McKean County 2
Centre County 2
Sullivan County 2
Venango County 1
Luzerne County 1
Bradford County 1
Jefferson County 1
Blair County 1
Northampton County 1
Berks County 1
8 other counties 8

The complete county distribution, spread across 20 Pennsylvania counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

American ermine hunts well above its weight class, killing rats and hares several times its own size before hauling the kill through tunnels barely wider than its skull. Pennsylvania’s 25 records come entirely from GBIF rather than iNaturalist, the kind of split you’d expect for a small, fast weasel that’s rarely caught on camera and more often turns up in trapping or specimen data.

Reports peak from May through July. That may reflect when ermines are easier to detect rather than a true population swell. With no NatureServe rank in this overlay for Pennsylvania, its state-level status isn’t formally assessed here. Pymatuning, Presque Isle, and Delaware Water Gap are useful places to start looking, but the records don’t establish that ermines are most abundant there.

Occurrence data from GBIF.

More mammals in Pennsylvania 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
  • 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"