Adders can be spotted as the weather begins to get warmer and they emerge from hibernation.

Photo: © Natural England/Allan Drewitt

Scientific name: Vipera berus

Cornish name: Nader

Other names: Common Viper

Conservation status: IUCN Red List, Least Concern; protected under the Wildlife and Countryside Act 1981; priority species in UK Biodiversity Action Plan.

The UK’s only venomous snake has a widespread European distribution. It is not uncommon in South West England, but is nationally in decline. It can be found, after emerging from its winter hibernation, in a variety of habitats, including heath, woods and clifftops. These habitats provide the adder with both shelter from vegetation and sunny spots to bask, enabling it to control its internal temperature and escape from danger.

It is instantly recognisable by the dark zig-zag stripe along its back. The larger females usually have a browner colouring compared to the more whitish-grey and black markings of the male: adders are one of the few snake species to exhibit sexual dimorphism. Melanistic adders occur very occasionally.

People have little to fear from adders, which are shy and will retreat rather than attack, other than when hunting their prey, which includes small mammals, amphibians, reptiles and nesting birds, or when attacked themselves. Very sensitive to ground vibrations, they are often long gone before you even see them.

Conservation threats to adders mainly come from habitat loss and disturbance, and a reduction in genetic diversity due to the resulting isolation of populations (known as inbreeding depression). 

Did you know…?  

…its range extends as far north as the Arctic Circle, where no other snake species is found

…the ‘dance of the adders’ is a territorial ‘duel’ between two males, but with no biting

More information and references:

Arnold, N. and Ovenden, D., 2002. Reptiles and Amphibians: Britain & Europe (Collins Field Guide), second edition. Collins, London.

Madsen, T., Stille, B. and Shine, R., 1996. Inbreeding depression in an isolated population of adders Vipera berus. Biological Conservation 75(2): 113–118.

Smith, M., 1973. The British Amphibians and Reptiles (The New Naturalist series), fifth edition. Collins, London. 

Published: May 2013
Photos: Photo: © Natural England/Allan Drewitt
Author: Amanda Scott