Are European vipers expanding their range?
Vipers (Vipera berus) are being observed in areas where no one has seen them ever before.
The viper (Vipera berus) is Norway and Northern Europe’s only venomous snake. It is found widely across the continent, even above the Arctic Circle. Yet now it seems as if the species is being found in more places than ever before. Or… maybe not?
The zigzag pattern on the European viper’s back is a good characteristic that can be used to identify this poisonous snake. But in some cases, the pattern may also be missing or difficult to see on certain snakes, so it’s not foolproof. Photo: NTB
“Based on reports we have received, we can assume that the viper has slowly expanded its range in Norway, but no one can say for certain,” says zoologist and associate professor emeritus Dag Dolmen, from the NTNU University Museum.
Dolmen is a herpetologist, a specialist in reptiles and amphibians, and among the foremost experts in this field in Norway.
“We have had some observations of vipers from new areas, and more vipers in old places. It’s reasonable to assume that this is due to the warmer climate,” Dolmen says.
But here, no one has a complete overview. Local conditions can also play a role in determining where these animals can live.
“We have a population in Trondheim that we have studied in Bymarka,” he said. Bymarka is Trondheim’s main public forest.
“But here it seems that there are fewer vipers in 2024 than there have been in the past,” he said. This may be due to the weather in Trondheim, which had a very hard winter in 2023-2024, with a number of days with little snow but very cold temperatures, he added.
The European viper
- Vipers (Vipera berus) are between 50 and 90 centimeters long. Females are larger than males.
- Some people think the young are the most poisonous. This is not true. Actually, the adults can inject more venom. But the chance of being bitten is very small.
- Another old wives' tale is that the females climb a branch when they are about to give birth, so that the young will fall to the ground before they have time to bite their mother. Perhaps a female once gave birth up in a tree, but in that case it would have been purely accidental.
Many viper species, but only one in Norway
Norway’s only viper belongs to the viper family, which includes around 200 species. But the species you find in Norway is also the only viper species that lives freely in Northern Europe.
However, the species is widespread in both Europe and Asia.
The European viper is often easily recognized by the zigzag pattern on its back. But the pattern can be intricate or impossible to see on the darkest specimens.
Here’s a dark form of a European viper, photographed crossing a road. It’s difficult to see the zigzag pattern on this animal. Photo: Nina Tveter, NTNU
If you’re not used to snakes, and perhaps a little frightened of them as well, you might be confused if you come across a grass snake (Natrix natrix) or a patterned smooth snake (Coronella austriaca) instead. These two species are completely harmless, and along with the European viper, are the only wild snake species found in Norway.
So it’s probably not a bad idea to keep your distance for safety’s sake. But you shouldn’t harm them.
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So what if you see a viper?
“Vipers can be dangerous. You should always take viper bites seriously. People can die, and I know several people who would not have survived without prompt medical help,” Dolmen said.
There’s little risk of being bitten by a viper, but you can get injured if you get to close to them. Always take a viper bite seriously. Photo: NTB
A viper bite is consequently something that should be taken seriously. Seek help as soon as possible, and forget about the old-fashioned advice that suggests sucking out poison or tying a lace around the bite site.
“However, if you get bitten, it’s usually okay. A viper never attacks, but often defends itself if it is picked up or forced into a corner,” Dolmen said.
The best thing is to keep your distance. Also keep your pets away from this snake.
“If you see a viper out in the field: Don’t go any closer than 1 metre. Enjoy the view. It’s a great animal,” Dolmen.
But you also don’t need to be anxious if you forget to follow these precautions. You have to be really unlucky, and almost step on the snake to get bitten.
And these snakes are an important part of the Norwegian fauna. They are particularly important in keeping small rodent populations in balance, Dolmen said.
“The viper is an eminent mouse hunter that belongs in the Norwegian environment. It is also protected by law,” Dolmen said.
