Illinois is home to four venomous snakes – the cottonmouth, timber rattlesnake, eastern massasauga rattlesnake and copperhead – and the copperhead accounts for a large share of snake bites across the United States. Whereas a copperhead bite is rarely fatal, the venom can cause swelling, pain and, in some individuals, severe allergic reactions.
The Mississippi River corridor
The Mississippi River forms Illinois’s natural border with Missouri and is the second‑longest river in the United States, though it carries the largest discharge. Venomous snakes, especially cottonmouths and copperheads, frequent the river’s water’s edge, forests and bluffs. Copperheads are most common from central Illinois in Pike County down to the state’s southern border.
During the summer breeding season, snakes turn into more active at the same time that anglers and hikers visit the river parks, so vigilance is essential.
McCully Heritage Project
Located in Calhoun County, the 940‑acre McCully Heritage Project offers hiking, horseback riding, fishing ponds and a group camping area. Its wetlands, woods and grasslands provide ideal hiding places for eastern copperheads, which favor mixed woodlands and river bluffs and are strong swimmers.
Copperheads have hemotoxic venom that interferes with blood flow; they often deliver dry bites that contain little or no venom.
Giant City State Park
Set within the Shawnee National Forest near the Missouri border, Giant City State Park is known for its towering sandstone bluffs. Hikers frequently encounter copperheads on the trails; the snakes measure 20 to 37 inches and weigh just under a pound.
Unlike many venomous species that flee, copperheads often freeze, increasing the chance that a person might step on them. Copperheads are responsible for just shy of 39 % of all U.S. Snake bites each year.
Illinois Caverns State Natural Area
In Monroe County, Illinois Caverns is the state’s only commercial cave attraction. Visitors have reported copperheads guarding the cave entrance, taking advantage of the river‑bluff and stream habitats that connect to the Mississippi River corridor.
These snakes are federally protected; harming or harassing them is illegal.
Ferne Clyffe State Park
Ferne Clyffe State Park in Johnson County is celebrated for its diverse fern species and limestone bluffs. Its 18‑mile trail system traverses cliffs, ridges, waterfalls and a lake, providing ample shelter for copperheads, timber rattlesnakes and cottonmouths.
Like other pit vipers, copperheads remain motionless and strike from concealed positions, targeting rodents, lizards and little mammals.
Avoiding copperheads
The Illinois Poison Center advises against handling, trapping or feeding any snake. Hikers should watch where they step and avoid placing hands under rocks, logs or dense underbrush.
If bitten, remove jewelry from the affected area, preserve the limb at heart level and seek immediate medical care. Do not apply ice, tourniquets or attempt to suction the venom.
Frequently Asked Questions
Which venomous snakes are found in Illinois?
Illinois hosts four venomous species: the cottonmouth, timber rattlesnake, eastern massasauga rattlesnake and copperhead.
What should I do if I am bitten by a copperhead?
Remove any jewelry from the bite, keep the affected limb at heart level, avoid ice or tourniquets, and seek prompt medical attention for antivenom treatment.
Why do copperheads often freeze instead of fleeing?
Copperheads tend to remain motionless when approached, which can make them harder to see and increase the likelihood of accidental contact.
How will you adjust your outdoor plans this summer to stay safe around Illinois’s copperhead habitats?
