5 VENOMOUS Snakes Found in Iowa! (2023)
“What kinds of venomous snakes can you find in Iowa?”
This question is extremely common. Everyone wants to know if any dangerous snakes live near them and what they look like!
Believe it or not, you can find FIVE types of venomous snakes in Iowa. But please don’t live in fear, thinking that you are going to be bitten. In general, snakes try to avoid any contact or interaction with people. As long as you leave them alone, you shouldn’t have any trouble!
Did you know that snakes are considered venomous, NOT poisonous? If you eat something that makes you sick, then it’s considered “poisonous.” If an animal, like a snake, delivers its toxins when it bites, then it’s considered “venomous.”
*If you come across any of these species, PLEASE DO NOT DISTURB! Venomous snakes are dangerous animals and should be left alone. The more you agitate them, the more likely you could get bitten. DO NOT RELY ON THIS ARTICLE to correctly identify a snake that has recently bitten you. If you have recently been bitten, GO DIRECTLY to the nearest hospital to get help and to determine if the snake is venomous.*
5 Venomous Snakes That Live in Iowa:
#1. Eastern Copperhead
- Agkistrodon contortrix
Identifying Characteristics:
- Adults reach lengths between 20 and 37 inches.
- Stout body and broad head and elliptical pupils.
- Coloration varies from pale tan to pinkish-tan with darker, splotchy, hourglass-shaped bands, which are darker at the edges and thinner towards the center of the back.
Look for these venomous snakes in the very southeastern corner of Iowa in deciduous forests and mixed woodlands, often near rocky outcroppings. However, they may also be seen in swampy areas, coniferous forests, and near river habitats. You’re most likely to see them active during the day in the spring and fall when the weather is cooler. During the middle of summer, Eastern Copperheads are often nocturnal.
Eastern Copperhead Range Map
Credit: Virginia Herpetological Society
This species is an ambush hunter, meaning that it selects a suitable site and waits to surprise its prey. In addition, copperheads are considered “pit vipers,” which means they have a heat-sensing organ located between their eyes. This adaptation helps these venomous snakes locate and judge the size of their prey by being able to sense infrared!
Bites from these venomous snakes are rarely fatal in Iowa.
The venom they produce has relatively low potency. In addition, copperheads also frequently employ false strikes, dry bites, and warning bites. Dry bites contain no venom, and warning bites have a relatively small amount of venom.
These snakes primarily feed on small rodents, frogs, birds, and large insects, such as cicadas. After the initial bite, they will wait for the venom to take effect before consuming their prey whole.
When threatened, Eastern Copperheads use a “freeze” defense. Their excellent camouflage coloration allows them to blend into the leaf litter and soil. However, they may also vibrate their tails in the leaves when approached to produce a buzzing sound. This noise may serve to warn predators, similar to a rattlesnake, or divert a predator’s attack to their tail.
#2. Timber Rattlesnake
- Crotalus horridus
Identifying Characteristics:
- Adults typically range from 30 to 60 inches in length.
- Coloration is variable, and generally ranges from yellowish brown to gray to almost black. Look for dark brown or black crossbands on their back.
- Heavy-bodied with characteristic rattle on the tail.
The Timber Rattlesnake, which is also known as the Canebrake Rattlesnake, can be found in a wide variety of habitats in Iowa. Look for these venomous snakes in lowland thickets, high areas around rivers and flood plains, agricultural areas, deciduous forests, and coniferous forests.
Timber Rattlesnake Range Map
Credit: Virginia Herpetological Society
These venomous snakes are ambush predators, waiting for unsuspecting prey to come within range of their strike. They feed primarily on small mammals but may also consume frogs, birds, and other smaller snakes. Timber Rattlesnakes strike their prey and release them, waiting until the venom has taken effect before eating them.
These venomous snakes are potentially the most dangerous species found in Iowa due to their large size, long fangs, and high yield of venom. Luckily, Timber Rattlenskaes have a mild disposition and don’t often bite. They typically give plenty of warning by rattling and posturing.
The Timber Rattlesnake has played an interesting role in U.S. history. As it can be found in the area of the original 13 Colonies, it was used as a symbol during the American Revolution. In 1775 it was featured at the center of the “Gadsden Flag.” This yellow flag depicts a coiled and ready-to-strike Timber Rattlesnake and the words “Don’t Tread on Me.”
#3. Prairie Rattlesnake
- Crotalus viridis
Identifying Characteristics:
- Adults typically range between 3.3 and 5 feet in length.
- Coloration is highly variable and can be greenish-gray, olive green, greenish-brown, light brown, or yellow. All variations have dark blotches on the body that turn into rings near the tail.
- Broad triangular head, elliptical pupils, heat-sensing pits between the eyes and nostrils, and a tail rattle.
These venomous snakes can be found in northwestern Iowa in open prairies, grasslands, semi-desert shrublands, and forested environments. They can even be found at elevations up to 9500 feet!
Prairie Rattlesnake Range Map
The Prairie Rattlesnake hibernates during the winter, often in communal dens. These dens are typically rock crevices, caves, or old mammal burrows. Individual snakes will return to the same den each winter and migrate up to seven miles to their hunting grounds in the spring.
When they feel threatened, these snakes will freeze, trying to use their camouflage to avoid detection. They may also quietly crawl away to cover. If approached, they may coil and rattle their tail as a warning before striking. Their potent venom has both hemotoxic and neurotoxic properties, and although rare, can be fatal to an adult human.
Prairie Rattlesnakes are listed on the ICUN Red List as a species of least concern. However, they are considered threatened and declining in parts of their range. They have faced pressure from habitat fragmentation and hunting.
#4. Eastern Massasauga
- Sistrurus catenatus
Identifying Characteristics:
- Adults are typically around 2 feet in length.
- Coloration is gray or light brown with darker chocolate-brown blotches on the back and smaller ones on the sides, which feature light edges.
- Thick body, vertical pupils, heat-sensing pits between the eyes and nostrils, and heart-shaped head.
These small venomous snakes live primarily in wet habitats in eastern Iowa.
The name “Massasauga” actually comes from the Chippewa language and means “great river mouth” and describes their habitat. Look for them in floodplain forests, shrub swamps, low areas along rivers and lakes, wet prairies, moist grasslands, bogs, and marshes. During the summer, they often migrate to drier regions adjacent to these habitats.
Eastern Massasauga Range Map
Unlike other rattlesnakes, the Eastern Massasauga hibernates alone. They frequently hibernate in crayfish burrows but may also use small mammal burrows or spaces under rotting logs or tree roots. Dens must be below the frost line, or they risk freezing to death!
These snakes have cytotoxic venom (poisonous to cells) that destroys tissue, which also has the dangerous quality of disrupting blood flow and preventing clotting. But these snakes are secretive, shy, and avoids humans when possible. The only times they bite seem to be when handled or accidentally stepped on!
This venomous snake is listed as threatened, endangered, or a species of concern in all parts of its range. Historically, these snakes have faced pressure from hunting, and many states had bounties and roundups for them. Today they are still often killed out of fear AND face diminishing wetland habitat.
#5. Western Massasauga
- Sistrurus tergeminus
Identifying Characteristics:
- Adults range from 14 to 36 inches in length.
- Coloration is gray to light brown with dark brown blotches on the back.
- Thick body, large triangular head, heat-sensing pits between the eyes and nostrils, elliptical pupils, and rattle on the tail.
- Often referred to as the Prairie Massasauga.
The Western Massasauga is one of the smallest venomous snakes in the country! They primarily inhabit grassland habitats but can also be found in open sagebrush prairie, rocky hillsides, prairie hillsides, open wetlands, and grassy wetlands.
Western Massasauga Range Map
This venomous snake is secretive and is not often seen in Iowa.
When detected, they often freeze rather than rattling. However, when they do rattle, Western Massasaugas make a distinctive sound. Their rattle is significantly higher pitched than larger rattlesnakes and has earned this small snake the nickname “buzz tail.”
Though their venom is highly potent, the small quantity they deliver makes their bites much less likely to cause fatality in humans than some larger venomous snakes. However, you still need to respect them as their venom is hemotoxic and will cause localized swelling, extreme pain, and necrosis. Medical attention should be sought immediately if bitten!
Do you need additional help identifying a venomous snake?
I recommend purchasing a Peterson Field Guide to the Reptiles and Amphibians of North America. These books have lots of helpful information, including pictures and range maps. View Cost - Amazon
Which of these venomous snakes have YOU seen in Iowa?
Leave a comment below!
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