Big Brown Bat in Wyoming

Eptesicus fuscus

Native to Wyoming S5 Secure in Wyoming

Not listed as nonindigenous in Wyoming by USGS NAS; native to its Wyoming range.

IUCN Red List status

LC – Least Concern

Widespread and abundant; not at risk.

Photo: Connor Long · CC BY-SA 4.0Big Brown Bats (Eptesicus fuscus)Photo: rhododendrites · CC-BY-SABig brown bat flying in daylight with wings spreadPhoto: Dan Riskin · CC-BYBig brown bat flying at night with wings spreadPhoto: Rita Clare · CC0Big brown bat roosting on lichen-covered tree barkPhoto: Bonnie Isaac · CC0Big brown bat roosting on a wooden structure

Photo: Connor Long · CC BY-SA 4.0Big Brown Bats (Eptesicus fuscus)Photo: rhododendrites · CC-BY-SABig brown bat flying in daylight with wings spreadPhoto: Dan Riskin · CC-BYBig brown bat flying at night with wings spreadPhoto: Rita Clare · CC0Big brown bat roosting on lichen-covered tree barkPhoto: Bonnie Isaac · CC0Big brown bat roosting on a wooden structure

Big Brown Bat in Wyoming, by the numbers

Occasional in Wyoming 72nd most recorded of 126 mammals logged in Wyoming

11 occurrence records

11 with iNaturalist photos

Feb 1, 2025 Last seen in Wyoming

Records from 2000–2026.

11 total records count every Wyoming occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 10; the monthly chart covers the 10 records with a full observation date.

When to look for the Big Brown Bat in Wyoming

Most sightings fall in July to August.

10 Wyoming 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 Wyoming records (table)

Month	Records
January	0
February	1
March	0
April	0
May	0
June	1
July	3
August	5
September	0
October	0
November	0
December	0

Monthly big brown bat occurrence records (iNaturalist and GBIF) in Wyoming, 2000–2026.

Seasonality

Sparse observation record in Wyoming; presence confirmed but timing of activity not well documented.

Occurrence map

Where Big Brown Bat has been recorded in Wyoming

10 records mapped · zoom and drag to explore

10 Wyoming records mapped

Notable places to look

Park, forest, or monument	iNaturalist records
Fort Laramie National Historic Site	1

Protected places with the most big brown bat 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 Wyoming

County	Records
Goshen County	4
Fremont County	2
Albany County	2
Sheridan County	1
Converse County	1
Other localities	1

The complete county distribution, spread across 5 Wyoming counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Big brown bat has just 11 Wyoming records, all of them research-grade iNaturalist observations, with Goshen County on the Nebraska line holding 4 and Fort Laramie National Historic Site the only named site. This is one of the most cold-tolerant North American bats, able to roost in buildings and rock crevices through much of the year rather than migrating long distances.

Most dated records fall in July and August, the height of summer insect foraging, though 11 records are too few to read as a firm seasonal pattern. NatureServe ranks the species S5, Secure, in Wyoming.

Occurrence data from iNaturalist and GBIF.

Full species profile Big Brown Bat Eptesicus fuscus Size 7.5 cm3 in Weight 17 g0.6 oz Lifespan 19 yr View the full profile

More mammals in Wyoming 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"