Minnesota has 2 venomous snakes named by official sources: Massasauga and Timber Rattlesnake. Each one is labelled venomous by Minnesota Department of Natural Resources, Nongame Wildlife Program.
The 2 venomous snakes of Minnesota
Recognize them from a distance; a photo cannot confirm that a snake is safe. Identifying animals safely.
Venom: “MASSASAUGA (Sistrurus catenatus) Venomous” (Minnesota Department of Natural Resources, Nongame Wildlife Program)
Habitat: Prefers moist habitats such as marshes and other wetlands, backwater areas, and bottomland forests; often forages in more open, upland areas adjacent to water bodies (Minnesota Department of Natural Resources, Nongame Wildlife Program)
WDFW: gopher snakes lack a rattle and facial pits and have smaller, square back spots. NPS Cabrillo: the gopher snake's tail is long, skinny and pointed with no rattle, its head is about as slender as its neck (rattlesnakes have large spade- or triangle-shaped heads), and its back pattern is a rectangular chain rather than the circles or diamonds of a rattlesnake. Caution: a defensive gopher snake flattens its head into a triangle and vibrates its tail, so do not rely on head shape or sound alone.
The timber rattlesnake has many small scales on top of the head (the massasauga has nine large plates), a uniformly black tail (the massasauga's tail has 4 to 7 black rings) and narrow, often chevron-shaped back bands rather than bow-tie-shaped blotches. INHS warns that head plates are hard to see on a live snake and says not to get close enough to check, because this is a venomous species.
Massasauga rattlesnake or Common (northern) watersnake?
The two massasaugas look almost the same; Missouri identifies them mainly by where they are found.
Photos show typical adults; individuals vary. Never get close to compare.
When venomous snakes are active in Minnesota
Records of snakes in Minnesota peak in May to June and September to October. They show when people record snakes, not how many there are (about month bars).
JanFebMarAprMayJunJulAugSepOctNovDec
547 records of snakes in Minnesota by month (GBIF, CC0 and CC BY records).
Do not try to capture or kill a rattlesnake or unidentified snake; most bites happen when people approach, handle or try to kill one. Minnesota Department of Natural Resources
Invasive insects (emerald ash borer, spongy moth, Asian long-horned beetle, brown marmorated stink bug): Minnesota Department of Agriculture "Report a Pest" line 1-888-545-6684. Invasive vertebrates (mute swans, Eurasian swine/wild pigs): the DNR Invasive Species Program and your local conservation officer or wildlife office. Aquatic invasives: your local DNR invasive species specialist. Cougar sightings: the nearest DNR area wildlife office or conservation officer. General DNR line: 888-646-6367. Minnesota Department of Natural Resources
“Minnesota has seventeen snake species, two of which are rattle‑ snakes, and three lizard species”
“Minnesota has two venomous snakes, both of which are rattlesnakes There are several characteristics that differentiate our rattlesnakes from our 15 nonvenomous snake species”
“MASSASAUGA (Sistrurus catenatus) Venomous”
“TIMBER RATTLESNAKE (Crotalus horridus) Venomous”
“Although timber rattlesnake bites are rarely life threatening, they should always be taken seriously”
“If you do not recognize a snake that you encounter, be safe Leave the snake alone, slowly back away, and if you need to pass the snake, stay at least 6 feet away”
“If you have a dog with you, it is important to get your dog on a leash or under your control until you are well past the snake”
“…they are typically only active in Minnesota from April through late October”
“May is the peak time for spring movements and September for fall movements, making them the peak months for most snake‑human encounters However, the peak encounter time for timber rattlesnakes in Minnesota is July through August”
“Water moccasins (cottonmouths) and copperheads do not occur in Minnesota”
“(Many people who encounter the common watersnake mistake it for a massasauga)”
Rare Species Guide: Massasauga. Minnesota Department of Natural Resources. archived copy, captured May 17, 2026; checked November 3, 2026.Quoted passages (1)
“The massasauga is one of Minnesota's two venomous snakes.”
“Report new locations to Minnesota Department of Agriculture or call the ‘Report a Pest’ phone number: 1-888-545-6684.”
Living with Wildlife: Snakes. Minnesota Department of Natural Resources. archived copy, captured October 25, 2026; checked November 3, 2026.Quoted passages (1)
“Of the 17 snake species in the state, only two are venomous -- the Timber Rattlesnake and the Eastern Massasauga. Both are found only in the southeastern counties and are rarely encountered.”
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