Ohio mammals

Big Brown Bat in Ohio

Eptesicus fuscus

Native to Ohio SNR Unranked in Ohio

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

Big Brown Bats (Eptesicus fuscus)Big brown bat flying in daylight with wings spreadBig brown bat flying at night with wings spreadBig brown bat roosting on lichen-covered tree barkBig 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 Ohio, by the numbers

Common in Ohio 18th most recorded of 75 mammals logged in Ohio

775 occurrence records
533 with iNaturalist photos

Records from 2000–2026.

775 total records count every Ohio occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300; the monthly chart covers the 763 records with a full observation date.

When to look for the Big Brown Bat in Ohio

Most sightings fall in July to August.

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

Monthly Ohio records (table)
MonthRecords
January30
February51
March47
April42
May77
June79
July160
August129
September70
October24
November32
December22

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

Seasonality

Year-round in Ohio, with recorded sightings peaking in July–August.

Occurrence map

Where Big Brown Bat has been recorded in Ohio

300 records mapped · zoom and drag to explore

300 Ohio records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Kiser Lake State Park 7
Portage Lakes State Park 2
John Bryan State Park 1
Mosquito Creek State Park 1
Kendrick Woods Nature Preserve 1
Clifton Gorge Dedicated Nature Preserve 1
Shawnee State Park 1
Fort Laurens State Park 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 Ohio

CountyRecords
Franklin County 106
Summit County 92
Cuyahoga County 55
Hamilton County 47
Hocking County 46
Champaign County 23
Medina County 19
Portage County 18
Clinton County 18
Logan County 16
Greene County 14
Delaware County 14
64 other counties 307

The complete county distribution, spread across 76 Ohio counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Big brown bat reports occur in every month of Ohio’s record set, but they are far from evenly distributed. July accounts for 127 of the 614 records and August adds 107; May is the next strongest month with 67, creating a distinct warm-season concentration rather than a flat year-round pattern.

Ottawa National Wildlife Refuge, Killdeer Plains Wildlife Area, and Mentor Marsh are the three Ohio settings named in the file, though no place-level counts are supplied for them. NatureServe lists the bat as SNR, unranked, in Ohio. Together, those limits mean the records establish when and where reports have been logged without showing population size or identifying a leading site.

Occurrence data from iNaturalist and GBIF.

Big Brown Bats (Eptesicus fuscus)
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 Ohio 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"