Black Grass Snakes Are Spreading in Germany

Black snakes are causing a stir in German cities – but the animals are harmless.

In several cities in North Rhine-Westphalia, such as Witten, Dortmund, and Essen, reports of black snakes are currently increasing. The animals appear in gardens, basement shafts, or even technical facilities, unsettling many people. However, experts give the all-clear: the animals are not poisonous exotics, but a native, completely harmless snake species – the grass snake.

Color Variant Due to Genetic Mutation

The black specimens belong to the species of grass snake (Natrix natrix), but exhibit a rare color variant: the so-called melanism. In this case, the animal produces an excessive amount of melanin – a natural pigment – causing the skin to appear completely black. This genetic mutation is not dangerous but represents a natural variance.

Climate Change Promotes Spread

According to experts like Martin Maschka from the Wilderness School Ruhr Area, climatic changes favor the spread of the grass snake – even in more densely populated regions. The warmer and wetter summers not only lead to a higher overall population but also to an increase in rare genetic variants.

Risk of Confusion with Adders

Melanistic grass snakes can easily be mistaken for the similarly dark but venomous adder. A reliable distinguishing feature is the shape of the pupils: grass snakes have round pupils, while adders have vertical ones. Additionally, the typical zigzag pattern on the back is absent in black grass snakes.

Behavior in Case of Emergency

If you encounter such a snake, you should remain calm and keep at least a one-meter distance. The animals usually flee immediately and pose no danger. A photo can help to accurately identify the species. Important: The grass snake is strictly protected – killing it can result in heavy fines.

Useful Garden Resident

The grass snake hunts amphibians and even repels mice with its scent. It is therefore a valuable part of the ecosystem. If you encounter one, you should be pleased with the rare visit – and not afraid.

Source: This article is partially based on information from PETBOOK, as of July 17, 2025.

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