Pennsylvania mammals

Western Little Brown Myotis in Pennsylvania

Myotis lucifugus

Native to Pennsylvania S1 Critically Imperiled in Pennsylvania

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

Occasional in Pennsylvania 36th most recorded of 73 mammals logged in Pennsylvania

52 occurrence records
27 with iNaturalist photos

Records from 2000–2026.

52 total records count every Pennsylvania occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 50; the monthly chart covers the 50 records with a full observation date.

When to look for the Western Little Brown Myotis in Pennsylvania

Most sightings fall in January.

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

Monthly Pennsylvania records (table)
MonthRecords
January17
February1
March0
April0
May4
June4
July3
August4
September5
October4
November8
December0

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

Seasonality

Year-round in Pennsylvania, with recorded sightings peaking in January.

Occurrence map

Where Western Little Brown Myotis has been recorded in Pennsylvania

50 records mapped · zoom and drag to explore

50 Pennsylvania records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Moraine State Park 2
Delaware Water Gap National Recreation Area 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 Pennsylvania

CountyRecords
Centre County 12
Mifflin County 9
Lawrence County 8
Luzerne County 4
Clearfield County 3
Butler County 3
Huntingdon County 1
Venango County 1
Forest County 1
Pike County 1
McKean County 1
Lackawanna County 1
5 other counties 7

The complete county distribution, spread across 17 Pennsylvania counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Despite the site’s “western” slug, this overlay contains Pennsylvania-scoped little brown bat records. Pymatuning and Presque Isle offer open insect-hunting water, while Delaware Water Gap adds wooded tributaries, cliffs, and buildings that may provide shelter.

Records peak in January and again in October and November. Finds at winter shelters or around structures can dominate cold-season data, so the pattern describes reporting circumstances, not the number of bats flying outdoors.

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 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
  • 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"