Quick facts

Common name(s):
adder, European adder, European viper

Scientific name: Vipera berus

Family: Viperidae (vipers)

Habitat: woodland, grassland, heathland

Diet: small mammals, amphibians, birds and reptiles

Predators: birds of prey and large mammals; young are particularly vulnerable to large birds

Origin: native

What do adders look like?

Male adders usually have silvery-grey colouration, while females can be copper or brown. Both have a distinctive, black zig-zag pattern along their backs. Fully black adders can be seen in some areas too.

Once fully grown, adders usually measure between 60 and 80cm in length. Young are almost perfect replicas of adults and measure around 17cm in length at birth.

Credit: Colin Varndell / Alamy Stock Photo

What do adders eat?

Adders feed primarily on small mammals, such as voles and mice, and lizards. They will also eat frogs, newts and small birds and their chicks. They are active during the day and use their venomous bite to subdue their prey.

Credit: Gillian Pullinger / Alamy Stock Photo

How do adders breed?

Adders mate after emerging from hibernation in spring, when males engage in elaborate ‘dances’ as they fight each other for access to females.

Unlike some snakes, adders do not lay eggs and instead give birth to up to 20 live young in late summer. The species has been known to live for more than ten years, although it can sometimes fall victim to other predators, such as birds of prey, crows and even pheasants, especially when young.

Do adders hibernate?

Adders hibernate through the coldest part of the year. From around October to March they sleep in sheltered, dry spots such as old rodent burrows or within fallen trees.

Did you know?

In Dorset folklore, finding an adder on your doorstep was a very bad omen.

The Anglo-Saxons thought that saying the word ‘faul’ would cure you of an adder’s bite.


Where do adders live?

Adders are found across Britain but are absent from Ireland. They are associated with open habitats such as heathland, moorland and woodland edges.

The adder is the most northerly-occurring snake species in the world and has been recorded within the Arctic Circle.


Grass snake or adder? How to tell the difference between UK reptiles

Karen Hornigold  •  01 Feb 2018

Discover more about our common native reptiles and where you can find them with this snakes and lizards guide.

Read our ID tips

Credit: pronature / Alamy Stock Photo

Signs and spotting tips

Your best chance of seeing an adder is in spring, when they are emerging from hibernation and spend the early part of the day basking in sunlight. They are sensitive to vibration and quick to slip away when they feel footsteps approaching.

These snakes are shy creatures that will naturally retreat from humans. It is rare for adders to bite people, but this can happen if humans try to handle them or accidentally step on them. Adder bites are rarely fatal, but can be very painful.

Threats and conservation

The UK’s adder population is in decline. Habitat loss is thought to be the leading factor in this worrying trend, with intensive agriculture destroying suitable habitat and causing adder populations to become fragmented and isolated. The species is fully protected by law.