Common European Adder
(Vipera berus)

Welcome to the Wildlife Wanderer species identification guide. This factfile covers the Common European Adder (Vipera berus), a striking, stocky snake found across the UK known for the distinctive dark zigzag pattern running along the length of its back.

Top-down view of a brown female adder showing her red eyes, and slit pupil.

Female Adder showing her zig-zag pattern.

Habitat & Distribution

Diet: Ambush predators. Adults use potent venom to hunt small mammals like voles, shrews, and wood mice, alongside lizards and ground-nesting birds. Young adders rely entirely on smaller, cold-blooded prey, primarily hunting for common lizards, small froglets, and surface invertebrates.
Habitat: Grassland, open woodland, heathland, moorland and coastal areas.
Distribution: Europe and Asia.
UK Distribution: Widespread across most of Britain.
Rarity: Near threatened and vulnerable in areas.

Physical Description & Identification Keys

Size: 60-70cm.
Description: A large rounded headed with a thick body. The colour can vary massively from light to dark, but usually there is a dark zigzag running the length of the body and tail. Melanistic (all black) variants do also exist. The head usually features a dark V or X marking, and there is usually a dark stripe from the eye to the neck that becomes a row of spots along the sides. The base colour can range from off-white and cream, to brown, dark brown and grey. The eyes are red to red-brown with vertically slit pupils.
The females tend to be brown in colour and the males grey.
The melanistic specimens are usually female.

Field Notes and Experiences

I have only ever encountered one wild adder, and that was found hidden amongst a large bushy area in the West Midlands. The specimen in the main image was captive, taken at the WildWood Trust in Kent.

My brother was bitten by an Adder, in an unfortunate event, and reacted badly. He was taken to hospital with anaphylactic shock and was close to death. The Adder is the UK's only venomous snake, and most of the time a bite is painful but non-lethal, however, as with bee stings, if a person is allergic to the venom it can become serious very fast.

Recognised Subspecies

Common European Adder (V. berus. berus) - UK
Balkan Cross Adder (V. b. bosniensis)
Sakhalin Adder (V. b. sachalinensis)

There are also three more proposed subspecies:

Baran's Adder (V. b. barani)
Alpine Common Adder (V. b. marasso)
Nikolsky's Adder (V. b. nikolskii)

The subspecies differ mainly in size, ground color, and back pattern.

Common European Adder Similar Species Comparison

Distinguishing Features: The UK only has three species of snake (ignoring the recently established Aesculapian Snake - Zamenis longissimus). The Barred Grass Snake (Natrix helvetica) is usually olive-green in colour, has a yellow and black collar around the neck and is larger, reaching up to 150cm in length. The Smooth Snake (Coronella austriaca) is smaller, averaging around 60-70cm, and features a series of barring and spotting rather than a zigzag pattern. The Adder is the only UK species to have red eyes and slit pupils, in the other two species, the pupils are round.

Colour Forms:

Albino Adder — (Pinkish-white skin with red eyes)
Bilineate Striped Adder — (Two parallel dark lines along the back)
Black-Backed Adder — (Solid black stripe down the spine)
Blue-Grey Adder — (Silver or ice-blue male ground color)
Blotched / Broken-Pattern Adder — (Zigzag broken into dots or bars)
Continuous-Striped Adder — (Unbroken dark dorsal stripe)
Copper / Red-Brown Adder — (Warm coppery-brown female ground color)
Dilute / Bleached Adder — (Pale, washed-out grey appearance)
Erythristic / Brick-Red Adder — (Vibrant brick-red to mahogany coat)
Melanic / Black Adder — (Solid black obscuring all pattern)
Ocellated Adder — (Zigzag split into pale-centered spots)
Spotless / Patternless Adder — (Normal background color without zigzag markings)
Straw-Yellow / Xanthic Adder — (Bright yellow base coat)