Sweden is home to a small number of native snake species, which often surprises those who associate the country primarily with cold climates. Despite its northern latitude, diverse landscapes, particularly in the warmer southern and coastal regions, provide suitable habitat for these reptiles. Understanding which species inhabit the country is important for safe coexistence and appreciating this unique aspect of Swedish wildlife.
Sweden’s Native Snake Species
Sweden hosts three distinct native snake species. The most commonly encountered non-venomous species is the Grass Snake (Natrix natrix), easily recognizable by the distinct yellow or off-white patches resembling a collar on either side of its neck. These dark snakes can grow quite large and are frequently found near water bodies, as they are strong swimmers that primarily feed on amphibians and fish.
The second non-venomous species is the secretive Smooth Snake (Coronella austriaca), which is smaller and much less commonly observed. This snake lacks the zigzag pattern of its venomous relative, featuring a slender, smooth, uniform appearance, often gray or brown. The Smooth Snake specializes in hunting lizards and small rodents by constriction. The third species, the European Adder, is the only venomous snake in the country.
The Only Venomous Snake
The European Adder (Vipera berus) is Sweden’s sole venomous snake and is distributed across nearly the entire country. It is often identified by a prominent dark zigzag pattern running along its back, though some individuals, known as melanistic adders, can be entirely black. The Adder’s pupils are narrow and vertical, distinguishing them from the round pupils of the non-venomous Grass Snake.
The venom causes significant local effects at the bite site. Typical symptoms include immediate, severe local pain, followed by progressive swelling, bruising, and bluish discoloration of the skin. While fatalities are extremely rare (only one death is recorded roughly every eight years in Sweden), systemic symptoms can be serious, including dizziness, nausea, vomiting, and a drop in blood pressure. Anyone who sustains an Adder bite must remain calm, keep the bitten limb immobile, and seek emergency medical attention immediately for monitoring and possible antivenom administration.
Geographic Distribution and Habitat
The Adder’s ability to survive in cold climates is unparalleled; it is found further north than any other snake species globally, even occurring above the Arctic Circle in Sweden. They are most often encountered in sun-exposed areas such as open heathlands, rocky slopes, forest clearings, and the edges of marshlands.
These reptiles emerge from hibernation early in the spring and spend considerable time basking in the sun to raise their body temperature. This behavior makes them most visible during the spring and early summer when they are less inclined to hide. Their preference for sunny, open ground means encounters are most likely in areas where humans also enjoy the outdoors, such as hiking trails and coastal areas.
Legal Protections and Encounter Guidelines
All native reptile species in Sweden, including the venomous Adder, are protected under national law, making it illegal to intentionally harm or kill them. However, the law makes a limited exception for the Adder: if a snake is found on private property or near a residence, it may be caught and safely relocated a few kilometers away.
The most effective way to prevent an unwanted encounter is to make noise and wear appropriate footwear, such as sturdy boots, when walking through high-risk habitats. Snakes typically flee when they sense the vibrations of approaching footsteps, as they are non-aggressive and prefer to avoid confrontation. If a snake is found in a yard, the recommended guideline is to encourage it to leave gently using a long stick or by spraying it lightly with water, focusing on relocation to comply with protective laws.