8 Types of Bats in Illinois
Yes, Illinois hosts at least 13 bat species. Big brown and little brown bats are the most common. Look for them near water, forests, and old buildings at dusk from late spring through early fall. Start your search in state parks or along the Mississippi River.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated June 6, 2026.
- 5
- species recorded
- May, July, August
- peak months
Verified species, source iNaturalist
8 types of bats recorded in Illinois
8 bat species have a verified observation record in Illinois across bats (order Chiroptera), each with at least 10 confirmed sightings. The full list, ranked by how often each is recorded, is below.
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Plus 6 more recorded only rarely (fewer than 10 verified sightings). Counts from verified iNaturalist observations. Photos by iNaturalist observers, reused under the licence each observer chose.
Real sighting data, source iNaturalist
1,338 verified observations on iNaturalist of bat have been recorded in Illinois, most often in May, July, August.
Yes, Illinois hosts at least 13 bat species. Big brown and little brown bats are the most common. Look for them near water, forests, and old buildings at dusk from late spring through early fall. Start your search in state parks or along the Mississippi River.
1. What Are the Most Common Bat Species in Illinois?
The big brown bat (Eptesicus fuscus) and little brown bat (Myotis lucifugus) are the species you'll most likely encounter across Illinois. The big brown bat is larger, with a wingspan up to 13 inches and a coppery brown coat. The little brown bat is smaller, roughly 3 to 11 grams, with glossy brown fur. A third species, the Indiana bat (Myotis sodalis), is endangered and more rare, found mainly in southern cave regions during winter. For comparison, see our guide tobats in the Midwest.
2. Where in Illinois Do People Usually First Spot Bats?
Most first sightings happen near water sources: along the Mississippi and Illinois Rivers, Lake Michigan shoreline, and smaller lakes in state parks like Starved Rock or Giant City. Suburban homeowners often notice bats around dusk over backyard ponds or near attic vents. Urban areas like Chicago also have bats; look in Lincoln Park or along the Chicago River at twilight. For more Illinois wildlife spotting tips, visit theIllinois wildlife hub.
3. When Is the Best Season and Time of Day to See Bats in Illinois?
Bats are active from April through October, with peak visibility in July and August when pups begin foraging. The best time is 20 to 30 minutes after sunset, especially on calm, warm evenings with low wind. Spring and fall migrations bring higher diversity, but daily emergence from roosts is your best bet. Winter bats hibernate, so sightings drop off sharply after October.
See ourstate animal guidefor the next step.
4. How Can You Identify Different Bat Species by Size and Color?
Start with size and ear shape. Little brown bats have small, pointed ears and a plain brown face. Big brown bats have broader, blunt ears and a larger body. The red bat (Lasiurus borealis) is smaller with rusty red fur and white shoulder patches, often seen in trees. The hoary bat is larger, frosted, and has a wingspan up to 16 inches. To separate lookalikes, note flight patterns: little browns flutter, while big browns fly straight. For more on bat identification, check ourbat species ID page.
5. What Habitats Do Bats Prefer Across Illinois?
Forest edges, riparian corridors, and agricultural areas with nearby water draw the most bats. Bridges, barns, and old sheds serve as daytime roosts. Caves in southern Illinois (like the ones at Cave-in-Rock State Park) host hibernating species in winter. For the highest diversity, visit river floodplains in summer. Remember, evening emerged bats often commute along tree lines. For a broader look at Illinois wildlife, seeour state wildlife page.
6. Where to Find Bat-Themed Apparel and Accessories
Once you've spotted your first bat, you might want to show some appreciation. Easy Street Markets carries a range of bat-themed items for fans of these flying mammals. Consider the **Cute Bat Sticker** to deck out a water bottle or laptop. For casual wear, the **Bat Animal Short-Sleeve T-Shirt** and **Baby Bat Cartoon T-Shirt** are comfortable, field-tested options. Browse the full collection at ourbat t-shirts page.
Cute Bat Sticker
A durable vinyl sticker perfect for gear, notebooks, or any smooth surface. Shows a charming bat design.Check Price and Availability
Bat Animal Short-Sleeve T-Shirt
A classic tee with a detailed bat graphic. Lightweight and soft for summer evening field trips.Check Price and Availability
Baby Bat Cartoon T-Shirt
A playful, fun design perfect for bat lovers of all ages. Makes a great gift for kids or young-at-heart.Check Price and Availability
Frequently Asked Questions About Bats in Illinois
**Q: What is the largest bat in Illinois?** The hoary bat is the largest, with a wingspan up to 16 inches. It's a tree-roosting species seen during fall migration.
**Q: Are there any endangered bats in Illinois?** Yes, the Indiana bat is federally endangered. It hibernates in caves in southern Illinois. Disturbing hibernating bats is illegal.
**Q: How do I tell a bat from a bird at dusk?** Bats have erratic, fluttering flight patterns while birds fly more steadily. Bats also show a distinct wing motion (fingered, not solid). Use a dark silhouette against the sky.
**Q: Can you attract bats to your backyard in Illinois?** Install a bat house on a pole or building at least 10 feet high, facing south or southeast, near a water source. Clean houses annually.
**Q: Where can I go for a guided bat walk?** Many state parks like Starved Rock and the Illinois Department of Natural Resources host evening bat programs in summer. Check local events.
7. Travel Widget: Find Bat Watching Spots in Illinois
Use this tool to find top bat-viewing locations, nearby roosts, and seasonal emergence times across Illinois.
See ourtour planning ideasfor the next step.
Gear and field guides
Frequently asked questions
1. What Are the Most Common Bat Species in Illinois?+
The big brown bat (Eptesicus fuscus) and little brown bat (Myotis lucifugus) are the species you'll most likely encounter across Illinois. The big brown bat is larger, with a wingspan up to 13 inches and a coppery brown coat. The little brown bat is smaller, roughly 3 to 11 grams, with glossy brown fur. A third species, the Indiana bat (Myotis sodalis), is endangered and more rare, found mainly in southern cave regions during winter. For comparison, see our guide tobats in the Midwest.
2. Where in Illinois Do People Usually First Spot Bats?+
Most first sightings happen near water sources: along the Mississippi and Illinois Rivers, Lake Michigan shoreline, and smaller lakes in state parks like Starved Rock or Giant City. Suburban homeowners often notice bats around dusk over backyard ponds or near attic vents. Urban areas like Chicago also have bats; look in Lincoln Park or along the Chicago River at twilight. For more Illinois wildlife spotting tips, visit theIllinois wildlife hub.
3. When Is the Best Season and Time of Day to See Bats in Illinois?+
Bats are active from April through October, with peak visibility in July and August when pups begin foraging. The best time is 20 to 30 minutes after sunset, especially on calm, warm evenings with low wind. Spring and fall migrations bring higher diversity, but daily emergence from roosts is your best bet. Winter bats hibernate, so sightings drop off sharply after October. See ourstate animal guidefor the next step.
4. How Can You Identify Different Bat Species by Size and Color?+
Start with size and ear shape. Little brown bats have small, pointed ears and a plain brown face. Big brown bats have broader, blunt ears and a larger body. The red bat (Lasiurus borealis) is smaller with rusty red fur and white shoulder patches, often seen in trees. The hoary bat is larger, frosted, and has a wingspan up to 16 inches. To separate lookalikes, note flight patterns: little browns flutter, while big browns fly straight. For more on bat identification, check ourbat species ID page.
5. What Habitats Do Bats Prefer Across Illinois?+
Forest edges, riparian corridors, and agricultural areas with nearby water draw the most bats. Bridges, barns, and old sheds serve as daytime roosts. Caves in southern Illinois (like the ones at Cave-in-Rock State Park) host hibernating species in winter. For the highest diversity, visit river floodplains in summer. Remember, evening emerged bats often commute along tree lines. For a broader look at Illinois wildlife, seeour state wildlife page.
Keep exploring
More places to see bat
More wildlife in Illinois