Species in the spotlight - The Adder

Photo: Andrew Neal 

Adders (Vipera berus) are the UK’s only venomous snake. Usually appearing from hibernation during March, Adders were spotted in Essex as early as February this year, due to the unseasonably warm temperatures.


Adders are a member of the viper family, Viperidae, which are classified by hollow, venom-conducting fangs in the upper jaw.

Adders are around 60-80cm long and can live up to 15 years. Like all snakes, Adders are ectothermic, which means they gain their heat from external sources, so they thermoregulate by basking in the sunshine to raise their body temperatures, unlike mammals which can regulate their body temperatures internally.

The ‘Adder dance’ can be seen from April onwards, where two males will wrestle energetically to win the right to mate with the female, however, females can mate with several males during a mating season and can also preserve and use sperm from previous mates. Females are ovoviviparous, meaning they incubate the eggs internally and the young are born live. Males are usually spotted earlier than females as they move around in search for a mate.


Photo: Karl Price

How to identify

You can identify an adder by the distinctive zig zag pattern that runs the length of its back, its grey/brown colour and its red eyes. Males tend to be greyer in colour, whilst females more reddish brown. Black melanistic forms have also been spotted in this species.


Adders occupy woodland, heathland and moorland and are found throughout the UK except mainland Ireland. They are also the only snake in the world to be found inhabiting areas within the Arctic Circle!

Feeding habits

Misunderstood by many, the Adder is a shy, secretive reptile that prefers to be hidden in the undergrowth than confronting humans. Well camouflaged in dense vegetation they will slither away from heavy vibrations to avoid detection. They instead use their venom to immobilise and kill their prey, consisting of small mammals, reptiles and ground nesting birds. Because of their timid nature, Adder bites are extremely rare, but do keep a safe distance if you see one, keep your pets on a lead and watch your footing if you're walking somewhere where Adders are known to be found.


Photo: Jon Hawkins

Conservation status

Threats that have led to recent Adder declines include habitat loss, fragmentation and persecution. Adders are protected in the UK under the Wildlife and Countryside Act, 1981. They are a priority species under the UK Post-2010 Biodiversity Framework and classified as a Priority Species in the UK Biodiversity Action Plan. You can help by getting in touch with Essex Wildlife Trust to find out more about volunteering, where you can help with habitat management whilst learning new skills and meeting like-minded people!

Where to see

You can see Adders up until October; before they return to hibernation. Here are a few of Essex Wildlife Trust sites you’ll be in with a chance of spotting one:


Photo: Max Martin