Range

Common vipers are the most widespread member of the viper family. Their range extends across Europe and Asia. Here they can be found in the following countries; Albania, Austria, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, China, Croatia, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Korea, Democratic People's Republic of, Latvia, Lithuania, Moldova, Mongolia, Montenegro, Netherlands, North Macedonia, Norway, Poland, Romania, Russia, Serbia, Slovakia, Slovenia, Sweden, Switzerland and the United Kingdom.

Habitat

They make their home in a number of habitats including Arctic tundra, the alps, forest, shrubland, grassland, wetlands, alpine meadows, dunes and marshes.

Typically areas which they call home are humid.

Reproduction

Breeding takes place in the spring though females typically only breed once every two to three years.

Males gather at a site know as the mating ground where females will come and select a mate. These females will be swarmed by a selection of males and can select one to mate with.

Once the female selects her mate they will remain together for hours and mate repeatedly. If another male attempts to steal his female they will battle by raising their body and intertwining it with their opponent. The males then attempt to force one another to the ground.

A male can mate with multiple females throughout the same breeding season.

The eggs develop inside the female and they give birth to live young. Each litter can include 20 young. These snakes may each have different fathers if their mother had multiple mates.

Soon after birth the females leave their mother and are independent from then on.

Young common adders are 16-18cm (6.3-7.1in) long.

In some areas the young adders are born during hibernation. At birth they have a fat reserve off of which they can survive for the rest of the hibernation till it is warm enough to emerge.

Sexual maturity is reached at 3-4 years old.

Behavior

Common adders emerge during the day to bask in the sun.

In the southern areas of their range the common adder will be active year round. In colder northern areas they will hibernate. In some areas this lasts for up to 8 months. They spend the hibernation in a burrow underground. Typically this has been formed by a mammal or reptile beforehand.

Each hibernation burrow can provide housing for up to 100 snakes.

Outside of mating and hibernation the common adder spends most of its time alone.

Predators and Threats

They face predation from a number of species including the foxes, badgers, birds of prey, owls and larger snakes.

To avoid predation their main defense if to camouflage with the environment and this is assisted by their colouration. If a predator does challenge them they can bite with their venom to scare them away.

Humans affect their population through deforestation. The main threat presented by humans though is killing due to the perceived threat due to them being venomous.

Quick facts

The common adder has many different names including the common viper, crossed viper or Northern palaearctic viper.

They are the only venomous snake which can be found in northwest Europe.