Illinois mammals

Eastern Red Bat in Illinois

Lasiurus borealis

Native to Illinois S5 Secure in Illinois

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

Eastern red bat roosting among green leaves, disguised as a dead leafEastern red bat in flight against blue skyEastern red bat roosting on a pine branchEastern red bat hanging under tree leavesEastern red bat tucked among white apple blossoms
Photo: NPS Photo · Public DomainEastern red bat roosting among green leaves, disguised as a dead leafPhoto: Chrissy McClarren and Andy Reago · CC0Eastern red bat in flight against blue skyPhoto: Christina Butler · CC BY 2.0Eastern red bat roosting on a pine branchPhoto: Summit Metro Parks · CC-BYEastern red bat hanging under tree leavesPhoto: Rev. Lee A. Payne, Jr. · CC-BYEastern red bat tucked among white apple blossoms

Eastern Red Bat in Illinois, by the numbers

Common in Illinois 20th most recorded of 80 mammals logged in Illinois

515 occurrence records
273 with iNaturalist photos
Jul 6, 2026 Last seen in Illinois

Records from 2000–2026.

515 total records count every Illinois occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300; the monthly chart covers the 505 records with a full observation date.

When to look for the Eastern Red Bat in Illinois

Most sightings fall in August to September.

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

Monthly Illinois records (table)
MonthRecords
January3
February7
March16
April63
May65
June56
July56
August70
September96
October56
November16
December1

Monthly eastern red bat occurrence records (iNaturalist and GBIF) in Illinois, 2000–2026.

Seasonality

Year-round in Illinois, with recorded sightings peaking in August–September, with a smaller rise in April–May.

Occurrence map

Where Eastern Red Bat has been recorded in Illinois

300 records mapped · zoom and drag to explore

300 Illinois records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Kankakee River State Park 3
Shawnee National Forest 2
Robert Allerton Park 1
Franklin Creek State Natural Area 1
Ferne Clyffe State Park 1
Red's Landing 1
Green Space East 1
Larue-Pine Hills National Natural Landmark 1

Protected places with the most eastern red 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 Illinois

CountyRecords
Cook County 299
DuPage County 32
Jackson County 31
Champaign County 22
Winnebago County 14
Madison County 13
Union County 12
Lake County 9
Will County 7
McLean County 5
Johnson County 4
Williamson County 4
33 other counties 63

The complete county distribution, spread across 45 Illinois counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Kankakee River State Park carries the clearest named cluster of eastern red bat reports in Illinois. Starved Rock and Upper Mississippi refuge lands continue the pattern along wooded river corridors, where trees provide daytime roosts and open water creates room to hunt.

September rises above the other months in the reporting series. Seasonal movement may contribute, but bat surveys and detector use also shape the record, so the peak isn’t a direct measure of abundance.

Eastern red bat roosting among green leaves, disguised as a dead leaf
Full species profile Eastern Red Bat Lasiurus borealis Size 9.3–11.7 cm3.7–4.6 in Weight 7–13 g0.2–0.5 oz Lifespan Up to 2.6 yr View the full profile

More mammals in Illinois 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"