2 Venomous (Poisonous) Snakes in Wisconsin

Rattlesnakes While HIking - Timber Rattlesnake
© Joe McDonald/Shutterstock.com

Written by Cindy Rasmussen

Updated: September 16, 2023

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There are 21 different species of snakes in Wisconsin, but how many of them are venomous (poisonous)? Are some of them more dangerous than others? Where do the venomous snakes in Wisconsin live? How can you avoid them? Here is everything you need to know about the 2 venomous (poisonous) snakes in Wisconsin!

List of snakes in Wisconsin

What are the 2 Venomous (Poisonous) snakes in Wisconsin?

Wisconsin’s 2 Venomous (Poisonous) snakes are the Timber Rattlesnake and the Eastern Massasauga.

1) Timber Rattlesnake

Timber Rattlesnake coiled on a rock

Timber Rattlesnakes can get to 3-5 feet long and are thick-bodied.


Timber rattlesnakes are some of the largest rattlesnakes in the United States. They are thick-bodied snakes typically 3-5 feet long but can reach lengths of 7 feet. Timber rattlesnakes vary in coloration and patterns, but some have a tan base color with dark brown markings. As a pit viper, they have a triangular head with pits (openings) on the side of their head that is used as an infrared sensor for sensing prey. As their name suggests, they have rattles at the end of their tail, which they will shake as a warning to others.

Where in Wisconsin do Timber Rattlesnakes live?

Timber Rattlesnakes can only be found in the SW counties of Wisconsin. They live in open-canopy bluff prairies and can hide in brush and under rock groupings. They are also excellent tree climbers, so keep that in mind if you are hiking in rattlesnake territory.

Are there Timber Rattlesnakes in any of the Wisconsin Parks?

If you are visiting any of the parks in the SW section of Wisconsin, check with the website as to the Timber Rattlesnake sightings. A Timber Rattlesnake was found and videotaped at Devil’s Lake State Park. This park is located just south of Wisconsin Dells and has 13 species of snakes, including northern water snakes, red-bellied snakes, and Black Rat Snakes. None of those species are venomous.

When are Timber Rattlesnakes out and about?

In Wisconsin, where temperatures can dip way below freezing, Timber Rattlesnakes will brumate (like hibernating) in the late fall and winter months. They come out around April 1st or when it starts to warm up. Timber Rattlesnakes have been known to combine in groups and sometimes with other snake species like Rat Snakes.

Has anyone ever been bitten by a Timber Rattlesnake in Wisconsin?

On average, someone gets bitten by a rattlesnake once every four years in Wisconsin, and it is extremely rare because there are few venomous snakes in the state.

What should you do if you come across a Timber Rattlesnake?

Suppose you are hiking and see a Timber Rattlesnake; keep your distance. Most snake bites occur when someone tries to handle or pick up a snake. Timber Rattlesnakes may rattle their tail as a warning and most likely slither away.

2) Eastern Massasauga

The Eastern Massasauga is one of the 2 venomous (poisonous) snakes in Wisconsin, and they are very rare in the state.

©Ryan M. Bolton/Shutterstock.com

One of the 2 venomous (poisonous) snakes in Wisconsin is the Eastern Massasauga. Although there have been sightings of Eastern Massasauga in Wisconsin, keep in mind that they are very rare. They are considered a State Endangered Species, and Federally they are a Threatened Species. They are easier to identify because they have a base color that is tan and dark brown splotches all over their backs. Massasaugas are also rattlesnakes, so they have a triangle head and rattle at the end of their tail. They are much smaller than the Timber Rattlesnake, with most only getting to be 2-3 feet long.

Where in Wisconsin do Eastern Massasauga’s live?

The Eastern Massasauga is very rare in Wisconsin, but its range is the southern border of the state and a few of the SW and central counties. These snakes prefer wetlands and will be found near water, and they can be found along floodplains, rivers, and fields next to lakes.

Are there Eastern Massasaugas in any of the Wisconsin parks?

 The Eastern Massasauga is limited to only a few wetlands in Wisconsin, so it is unlikely you will see one while enjoying one of Wisconsin’s State Parks.

What are biologists doing to help the Eastern Massasaugas in Wisconsin?

Because they are an endangered species in Wisconsin, biologists started to try to provide a better ecosystem for them. In 2019 a group of biologists and researchers gathered as many Massasaugas as they could to tag them so they could follow their movements. In the fall and winter, they will mow the grass and cut down trees in the snake’s habitat when they know the snakes are safely bromating. They are trying to create safe areas for the snakes to bask in the sun during the warmer months.

Has anyone ever been bitten by an Eastern Massasauga in Wisconsin?

No records exist of anyone being bitten by an Eastern Massasauga in Wisconsin.

Has anyone in the US ever been bitten by an Eastern Massasauga?

closeup of eastern massasauga

Eastern massasauga rattlesnakes are among the smallest rattlesnakes and enjoy wetter habitats than most rattlesnakes.

©Ryan M. Bolton/Shutterstock.com

Yes. In neighboring Michigan, eastern massasaugas bit two people in the same month! According to the Michigan Department of Natural Resources, two reported bites occurred in August 2018. The first victim was Phil Dawson, who was in his backyard looking for his cat when he accidentally stepped on a snake. It turned out to be an Eastern Massasauga. Phil got lucky because, after careful observation at the hospital, it was determined that it was a “dry bite,” meaning the snake did not release any of its venoms. It was still very painful.

The second incident occurred on August 20th when Laura Bowen walked out of her backyard shed with an arm full of boxes. She felt a sharp pain in her ankle and said she turned around to see a snake! This one did release its toxic venom, and she had to spend a week in the hospital while she received antivenin and recovered. Although Eastern Massasauga is also very rare in Michigan, they can come in contact with humans. Remember always to keep your distance from snakes, venomous and non-venomous.

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About the Author

I'm a Wildlife Conservation Author and Journalist, raising awareness about conservation by teaching others about the amazing animals we share the planet with. I graduated from the University of Minnesota-Morris with a degree in Elementary Education and I am a former teacher. When I am not writing I love going to my kids' soccer games, watching movies, taking on DIY projects and running with our giant Labradoodle "Tango".

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