Minnesota hosts approximately 17 native snake species, a smaller diversity compared to warmer regions due to its northern climate. The state’s varied habitats, from prairie grasslands to dense forests, are home to these reptiles. The vast majority are harmless and play a crucial role in the ecosystem. This overview differentiates between common non-venomous species and rare venomous inhabitants.
The Non-Venomous Majority
Most snakes encountered in Minnesota are non-venomous and belong to the Colubrid family. The most common is the Common Garter Snake (Thamnophis sirtalis). It is easily recognized by its dark body, typically black or brown, overlaid with three distinct lengthwise stripes that are usually yellow or whitish. These medium-sized snakes reach lengths of up to three feet and are found in nearly every habitat, including woodlands and suburban backyards.
The Eastern Milk Snake (Lampropeltis triangulum) is frequently observed and often mistaken for a venomous snake due to its striking pattern. It features a light background (gray or tan) with reddish-brown or grayish-brown blotches sharply outlined in black. This snake averages between two and three feet long. It typically displays a characteristic light-colored “Y” or “V” shape on the back of its neck.
The Western Hognose Snake (Heterodon nasicus) is a stout-bodied reptile known for its distinctive, upturned snout, which it uses for burrowing in sandy or gravelly soils. This prairie specialist rarely exceeds 20 inches and has a mottled pattern that helps it blend into its grassland habitat. When threatened, the Hognose Snake performs a defensive display, flattening its head like a cobra and playing dead, though it is harmless.
The Smooth Green Snake (Opheodrys vernalis) is Minnesota’s only entirely green snake, making it simple to identify. This small, slender species measures about one to two feet long. It has bright green dorsal scales and a yellow or off-white belly. Its smooth scales allow it to move easily through grass and shrubs, where it primarily hunts insects and spiders.
Identifying the Venomous Species
Only two venomous snake species are native to Minnesota, both pit vipers belonging to the rattlesnake group. The most established is the Timber Rattlesnake (Crotalus horridus), a large, heavy-bodied snake that can reach over four feet in length. Its body is typically rust-orange, yellow, or gray with distinct dark brown to black chevron-shaped crossbands.
Pit vipers share several specific identification features. The Timber Rattlesnake has a broad, triangular-shaped head and a narrow neck. The most obvious sign is a segmented rattle, which is cream-colored on a velvet-black tail, though newborns only possess a single “button.” These snakes also have heat-sensing pits located between the eye and nostril, and their pupils are vertically elliptical.
The second venomous species is the Eastern Massasauga (Sistrurus catenatus). It is smaller, averaging between 18 and 30 inches, and is considered extremely rare or possibly extirpated from the state. This rattlesnake has a grayish-brown body with a pattern of dark brown blotches along its back. Like the Timber Rattlesnake, it possesses a rattle, a triangular head, and vertical pupils, but it lacks the distinctive black tail.
Habitat and Geographic Distribution
The geographic distribution of Minnesota’s snakes is tied to the state’s diverse ecological regions. The Common Garter Snake is a generalist found statewide in a broad range of environments. Conversely, many other species are restricted to specific zones. The prairie and grassland habitats of western and central Minnesota are preferred by species like the Western Hognose Snake and the Bullsnake.
The state’s two venomous species are confined almost exclusively to the southeastern region known as the Driftless Area. This area, characterized by deep river valleys and limestone blufflands, provides the rocky crevices necessary for the Timber Rattlesnake to hibernate communally. The Eastern Massasauga, historically found here, prefers wet habitats, such as marshes and floodplains, particularly along the Mississippi River backwaters. Other species, like the Eastern Milk Snake, are also concentrated along river systems and rocky outcroppings in the southern half of the state.
Safety and Conservation
Encountering a snake requires simple, responsible behavior, as all snakes will avoid human contact if given the opportunity. The best action is to observe the animal from a distance and never attempt to handle or harass it. If a snake is found near a home, it should be left alone. Many harmless species will vibrate their tails in dry leaves to mimic a rattlesnake, a common bluffing defense mechanism.
Minnesota’s venomous species, the Timber Rattlesnake and the Eastern Massasauga, are protected under state law due to significant population declines. The Timber Rattlesnake is listed as threatened, and the Massasauga is designated as endangered. It is illegal to kill, collect, or disturb them. Protecting these reptiles helps maintain the ecosystem’s balance, as they control rodent populations.