Believe it or not, you can find FOUR types of rattlesnakes in Iowa!
But please don’t live in fear, thinking that you are going to be bitten. In general, rattlesnakes try to avoid any contact or interaction with people. The whole reason they have a rattle is to warn you to stay away! As long as you leave them alone, you shouldn’t have any trouble.
*If you come across any of these species, PLEASE DO NOT DISTURB! Rattlesnakes 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 rattlesnake that has recently bitten you. If you have recently been bitten, GO DIRECTLY to the nearest hospital to get help and determine if the snake is venomous.*
RELATED: The 26 Types of SNAKES Found in Iowa! (ID Guide)
#1. Timber Rattlesnake
- Crotalus horridus
- 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 a characteristic rattle on the tail.
The Timber Rattlesnake, also known as the Canebrake Rattlesnake, can be found in a wide variety of habitats in Iowa. Look for them 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 rattlesnakes 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.
Due to their large size, long fangs, and high venom yield, these rattlesnakes are potentially the most dangerous snake found in North America. Luckily, Timber Rattlenskaes have a mild disposition and don’t often bite. They also 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.”
#2. Eastern Massasauga
- Sistrurus catenatus
- 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, and a heart-shaped head.
These small rattlesnakes live 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. They often migrate to drier regions adjacent to these habitats during the summer.
Eastern Massasauga Range Map
It’s rare to hear an Eastern Massasauga rattle!
Instead, these small rattlesnakes typically remain motionless when threatened, relying on their small size and excellent camouflage to avoid predators. And even when they do use their rattle, it doesn’t sound like a traditional rattlesnake. Instead, the massasauga’s rattle has been described as a buzzing sound, similar to a bee stuck in a spider’s web!
This rattlesnake 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.
Getting bitten by an Eastern Massasauga in Iowa is incredibly rare due to their secretive and shy nature, combined with their threatened population. The only times they bite seem to be when handled or accidentally stepped on!
But if you are bitten, you should seek medical attention right away. These rattlesnakes have cytotoxic venom (poisonous to cells) that destroys tissue, which also has the dangerous quality of disrupting blood flow and preventing clotting.
#3. Prairie Rattlesnake
- Crotalus viridis
- 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, and a tail rattle.
These rattlesnakes can be found in small parts of western Iowa in open prairies, grasslands, and forested environments.
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, using 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. Their biggest threats are pressures from habitat fragmentation and hunting.
#4. Western Massasauga
- Sistrurus tergeminus
- 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.
The Western Massasauga is one of the smallest rattlesnakes 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 rattlesnake is secretive and is not often seen in Iowa.
When detected, they often freeze rather than make a rattle. 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 be fatal in humans than some larger rattlesnakes. 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 rattlesnake?
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.
Which of these rattlesnakes have YOU seen before in Iowa?
Leave a comment below!