Sweden is home to several snake species. Understanding which ones are present and their characteristics can help ensure safety.
Identifying Sweden’s Snakes
Sweden has three native snake species: the European adder (Vipera berus), the grass snake (Natrix natrix), and the smooth snake (Coronella austriaca). Among these, only the European adder is venomous and poses a potential danger to humans.
The European adder measures 50 to 70 centimeters, though some exceed one meter. It is identifiable by a distinct dark zigzag pattern along its back; some individuals, especially in Scandinavia, can be entirely black. Its head is often large and triangular with a V or X-shaped marking, and its pupils are vertical. Adder venom can cause localized pain, swelling, and discoloration, and systemic symptoms like dizziness, nausea, and difficulty breathing, though fatalities are rare.
The grass snake is non-venomous. These snakes can grow larger than adders, reaching up to 120 centimeters. They are usually olive-green, brown, or grey with distinctive yellowish-white patches behind their heads, resembling a collar. Grass snakes have round pupils and a smaller, less triangular head compared to adders. If threatened, they may hiss, release a foul-smelling fluid, or feign death, but they rarely bite.
The smooth snake is also non-venomous and less frequently encountered due to its secretive nature. These slender snakes measure 60 to 75 centimeters. They exhibit a grey or brownish coloration with a double row of dark spots or blotches along their back, which sometimes fuse, and a dark stripe extending from the nostril through the eye to the neck. Unlike adders, smooth snakes have smooth, glossy scales and a smaller head without the distinct V or X marking. They primarily prey on other reptiles, such as lizards, and are not considered aggressive towards humans, though they might bite if handled.
Where You Might Find Snakes
Snakes in Sweden emerge from hibernation when temperatures rise, from late April to early May. They bask in sunny spots to regulate their body temperature. During summer, snakes are most active in the mornings and evenings.
You are most likely to encounter snakes in areas that offer both basking spots and cover, such as rocky areas, heathlands, forest clearings, and pastures. Grass snakes, being semi-aquatic, are frequently found near water bodies like ponds, lakes, streams, and ditches, as well as in wetlands and backyard gardens. Adders inhabit a wide range of environments, including dry heath slopes, open woodlands, and areas with large rocks or stone mounds, often near marshlands or peat bogs. Smooth snakes prefer dry heathland habitats with sandy or rocky ground, often with scattered bushes and shrubs, providing both sun exposure and hiding places.
Safety When Encountering Snakes
Encountering a snake in Sweden requires a cautious approach, especially since the European adder is venomous. Always maintain a respectful distance and avoid provoking or handling any snake. Grass snakes are shy and will try to flee when approached, while adders, though not inherently aggressive, may strike if they feel threatened, for instance, if stepped on or picked up.
If an adder bite occurs, remain calm and keep the bitten limb still to slow venom spread. Elevating the affected area is also beneficial. Seek immediate medical attention by contacting emergency services or going to the nearest hospital; adder venom can cause significant pain, swelling, and other symptoms. While adder bites are rarely fatal, medical assessment is necessary, especially for children, the elderly, or those with underlying health conditions. If bitten by a non-venomous snake like a grass snake, medical attention is still recommended, mainly for wound cleaning and a possible tetanus shot, similar to any animal bite.
Avoiding tall grass during walks and maintaining clear areas around homes minimizes unexpected snake encounters.