Are There Bullfrogs in Illinois?
Yes, bullfrogs are common and well established throughout Illinois. You'll find these large, useful frogs in both northern and southern parts of the state, from Lake Michigan's marshes to the Mississippi River bottoms. They thrive in freshwater wetlands, ponds, and slow-moving rivers where cattails and aquatic plants provide cover and ideal breeding habitat.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated August 6, 2026.
Yes, bullfrogs are common and well established throughout Illinois. You'll find these large, useful frogs in both northern and southern parts of the state, from Lake Michigan's marshes to the Mississippi River bottoms. They thrive in freshwater wetlands, ponds, and slow-moving rivers where cattails and aquatic plants provide cover and ideal breeding habitat.
Where Bullfrogs Are Found in Illinois
Bullfrogs inhabit freshwater wetlands across Illinois from the Great Lakes region to the southern bottomlands. In northern Illinois, populations are concentrated around Lake Michigan marshes and throughout the Des Plaines River valley. The Illinois River system supports large bullfrogs populations, especially in the lower valley near its confluence with the Mississippi River. Southern Illinois offers extensive bullfrog habitat in the bottomland swamps and oxbow lakes of the Mississippi River floodplain and in shallow wetlands of the Cache River area. Bullfrogs have adapted well to artificial water bodies including farm ponds, retention wetlands, and quarry lakes throughout the state. Visitthe Illinois wildlife hubto learn about other amphibians sharing these habitats. Whether you're exploring northern lake marshes or southern swamp regions, freshwater wetlands at any elevation provide suitable bullfrog home across Illinois.
Season and Activity in Illinois
Illinois bullfrogs are most active from late spring through early fall when water temperatures warm. Their loud, resonant calls become audible by May and peak during breeding season in June and July. Late April through August represents prime bullfrog season when adults feed actively and juveniles metamorphose from tadpoles. In fall, as water temperatures cool by September and October, bullfrogs become less vocal and less visible, preparing for hibernation. By November, most bullfrogs have settled into deeper water or submerged mud where they overwinter in a dormant state. Spring emergence typically begins in April when water temperatures reach the upper 40s. Throughout the warmer months, bullfrogs are heard calling throughout the night, especially in the hours after sunset. The Illinoisbullfrog guideoffers more details on seasonal behavior patterns you can observe in your region.
How to Identify a Bullfrog
Bullfrogs are Illinois's largest native frogs, measuring four to six inches in body length. They have smooth, slippery green or olive brown skin with variations in coloration between individuals. The head is broad and flattened, with large prominent eardrums called tympana visible on the side behind each eye. Male bullfrogs develop a yellow throat in breeding season while females remain white or pale green underneath. Unlike many smaller frogs, bullfrogs lack toe pads or suckers, instead having webbed feet adapted for swimming. Their useful build and powerful hind legs distinguish them from the more slender green frog. Their most distinctive feature is their loud, resonant call that resembles the word "jug-o-rum" or a deep bass note. Listen for this unique call to confirm bullfrog presence in Illinois wetlands and learn more by visitingthe wildlife resource hub.
Where to See Bullfrogs in Illinois
Bullfrogs concentrate in shallow freshwater wetlands with emergent vegetation like cattails, bulrushes, and arrowhead plants. In northern Illinois, Crab Orchard National Wildlife Refuge near Carbondale provides excellent bullfrog habitat. The Kakagami Marsh State Nature Preserve offers prime viewing in central Illinois. Along the Mississippi River, backwater lakes and oxbow wetlands support dense bullfrog populations accessible from public access points. Farm ponds throughout rural Illinois host bullfrogs, especially larger ponds with vegetation established over several years. The Illinois River bottomlands from Morris southward contain extensive bullfrog habitat. Lake Michigan wetlands in Cook County provide accessible viewing areas. Sunset visits offer the best opportunity to hear bullfrog calls and spot individuals along shallow water margins. TheIllinois wildlife hublists additional wetland locations where bullfrogs are reliably found during breeding season.
Bullfrog Behavior and Diet
Bullfrogs are ambush predators that spend much of their time sitting motionless on the bottom or at the water's edge, waiting for prey to pass within striking distance. They eat insects including dragonflies, beetles, and mosquitoes, but also consume small fish, crayfish, tadpoles, and other small frogs including juvenile bullfrogs. Their powerful jaws can open very wide to accommodate large prey. Unlike smaller frog species that hunt primarily during day hours, bullfrogs actively feed at night and are most visible when calling or feeding in twilight hours. Males spend considerable energy defending territory during breeding season, often occupying the same small area of pond edge for weeks. Bullfrogs are solitary outside breeding season but may aggregate in favorable winter hibernation sites. They are primarily aquatic but can travel short distances overland during rainy weather. Their longevity in the wild can exceed ten years, making Illinois bullfrogs long term residents in established wetlands.
Coexistence and Legal Status
Bullfrogs are legal to possess for food in Illinois under regulated harvest seasons governed by the Illinois Department of Natural Resources. Bullfrog legs are harvested commercially in the state for culinary use, reflecting their significance as both native wildlife and food resource. Bullfrogs compete with native frog species and other aquatic predators for food and space, though they remain part of Illinois's natural amphibian group. They are not invasive in Illinois because they occur naturally here and maintain balanced populations within wetland ecosystems. Individual bullfrogs pose no threat to humans, and their presence indicates healthy wetland habitat. If you encounter bullfrogs, simply observe them from a respectful distance without handling them. Their nocturnal calling behavior is natural and does not reflect overpopulation. Protecting Illinois wetlands benefits bullfrogs and ensures their continued presence in the state. Learn more aboutwildlife conservationby exploring resources dedicated to wetland protection.
Species Often Mistaken for Bullfrogs
The green frog is the most commonly confused species with bullfrogs in Illinois. Both are large frogs with prominent tympana, but green frogs remain smaller, reaching only three to four inches. Green frogs have a visible ridge running down the middle of their back, which bullfrogs lack entirely. The pig frog, found in southern Illinois wetlands, is smaller and has a sharper snout than the bullfrog's broad head. Pickerel frogs are smaller and have distinctive square markings on their back rather than the bullfrog's relatively plain coloring. Leopard frogs have prominent round spots and are smaller and more delicate than bullfrogs. The bullfrog's larger size, broader head, and lack of a midback ridge distinguish it from all these similar species. Hearing their unique deep call helps confirm bullfrog presence. The best way to learn frog identification is visitingthe wildlife huband comparing multiple species side by side in your region.
Frequently Asked Questions
Q: Are bullfrogs native to Illinois? A: Yes, bullfrogs are naturally occurring frogs native to eastern North America, including Illinois. Q: Can bullfrogs freeze solid and survive? A: Bullfrogs move to deep water and mud for hibernation in winter but do not freeze solid. Ice forms over their habitat while they remain dormant below. Q: Do bullfrogs make good pets? A: Bullfrogs require substantial tank space, appropriate water quality, and live food. They are best observed in natural wetland settings rather than kept as pets. Q: What predators hunt bullfrogs in Illinois? A: Great blue herons, snakes, turtles, raccoons, and mink all prey on bullfrogs and help control their populations in wetland ecosystems.
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