The european grass snake is not venomous. If surprised the grass snake can secret a yellow and smelly substance from a couple of glands by the root of its tail.
The color of the grass snake can vary, but all have two yellow spots behind their head. The typical Danish/Nordic grass snake is black or brown.
Earlier the grass snake was common most places in Scandinavia, but the last couple of decades, the number of grass snakes has greatly decreased. This happens because of a reduction in suitable habitats, and a subsequent lack of food.