Wisconsin is home to a small number of native snake species. While many people assume snakes are dangerous, the vast majority found here are non-venomous and pose no threat to humans. The state’s diverse landscapes, from northern forests to southern prairies, support these reptiles. Learning their distinguishing characteristics is the first step toward safely appreciating their place in the ecosystem.
Identifying Non-Venomous Snakes
Non-venomous snakes are the most common reptiles encountered in the state, identified by several shared physical traits. Most species possess round pupils and a head that is generally spoon-shaped or no wider than their neck. They have a slender, pointed tail that tapers smoothly from the body, lacking a rattle or blunt end.
The Common Garter Snake is the most widespread species, recognized by its three light-colored stripes—often yellow or greenish—running down a darker body. These snakes are typically small to medium, ranging from 17 to 30 inches, and are frequently seen near water or grassy areas. The Eastern Milk Snake is another common species, identified by a pattern of reddish-brown blotches bordered in black against a gray or tan body. Young milk snakes may have a distinctive small yellow triangle or “Y” shape behind their head.
The Western Fox Snake grows much larger, reaching three to five feet, and is yellowish or tan with dark blotches along its back. Adult Fox Snakes sometimes have a reddish-orange or copper-colored head. Another frequent sighting is the Northern Water Snake, a robust species with brown, grayish, or reddish-brown banding or blotches. This snake is often misidentified as a venomous water moccasin, which does not live in Wisconsin.
Recognizing Venomous Species
Only two species of venomous snakes, both rattlesnakes, are native to Wisconsin, and encounters with either are rare. Both are classified as pit vipers, distinguished by unique features. Pit vipers have a broad, triangular-shaped head that is noticeably wider than their neck, as well as vertical, slit-like pupils.
The Timber Rattlesnake is the larger of the two, measuring between 30 and 60 inches, and is found in various color phases, from yellowish-brown to almost black. This heavy-bodied snake is identified by dark, often chevron-shaped, crossbands along its back and its rattle. The Eastern Massasauga Rattlesnake is smaller, typically reaching about two feet in length, and is gray or light brown with darker, chocolate-brown blotches.
A feature of pit vipers is the presence of a heat-sensing pit located between the eye and the nostril on each side of the head. The Massasauga’s rattle produces a quiet, insect-like buzzing sound, which is sometimes barely audible. Both species can strike quickly, but they usually give a warning rattle first, and are not aggressive unless threatened or handled.
Regional Habitats and Distribution
The distribution of Wisconsin’s snake population is influenced by the state’s varied geography and climate. Many species are more prevalent in the southern two-thirds of the state, where the climate is milder and the growing season is longer. The Common Garter Snake and Northern Water Snake are exceptions, as they are found throughout the entire state.
The state’s two venomous species occupy specific habitats. The Timber Rattlesnake is largely restricted to the rugged bluffs and rocky outcroppings of western and southwestern Wisconsin. This area is part of the “Driftless Area,” a region that escaped glaciation and features steep valleys and high-relief terrain that provides suitable den sites for hibernation.
The Eastern Massasauga is generally found in isolated localities across west-central and southeastern Wisconsin. These small rattlesnakes prefer wet habitats, such as floodplain forests, river bottom prairies, and moist grasslands. Habitat loss, particularly the draining of marshy wetlands, has significantly impacted the Massasauga population.
Conservation Status and Legal Protections
Many of Wisconsin’s native snakes are afforded legal protection under state and federal law. The state’s management of these species is outlined in the Wisconsin Administrative Code, specifically Chapter NR 27, which governs endangered and threatened species. This framework recognizes the ecological importance of snakes, which function in pest control and as a food source for other predators.
The Eastern Massasauga is listed as endangered in Wisconsin and is also designated as a federally threatened species under the U.S. Endangered Species Act. The Timber Rattlesnake is classified as a “protected wild animal” in Wisconsin, which prohibits the collection, hunting, or possession of the species. Killing, transporting, or possessing any wild animal on the state’s endangered or threatened list requires a specific permit.
Protection extends beyond the venomous species to include several non-venomous snakes that are rare or declining. The Northern Ribbon Snake and the Black Rat Snake, for instance, are also subject to special protections to safeguard their populations. These regulations prevent the disturbance, collection, or harming of protected species, and violations can result in significant fines.