The adder is our only venomous snake. It's a short and stocky creature, up to 70cm in length, the female being larger than the male. Contrary to popular belief, it's not an aggressive reptile, and although adders may hiss on being disturbed, they usually crawl away or 'freeze' until the danger has passed. 

One of the first reptiles to emerge from hibernation, sometimes as early as February, the male appears some 2 to 5 weeks before the female. Adders, like other reptiles slough or shed their skins every few weeks. The newly emerged snake will go through its first skin moult quite quickly. They rub their bodies along something rough, shedding their skin in one piece. After each skin moult, the colours of the snake are particularly vibrant.

The dark zig-zag pattern along its back makes the adder easy to distinguish from the grass snake, which also lives out on the mossland. Male adders have a black zig-zag, female adders, on the other hand, tend to be more brownish. 

The adders have red eyes with a vertical pupil, reminiscent of a cat's eye. This pupil shape is a feature of all venomous snakes.  

Adders will eat small mammals such as mice, shrews and voles, lizards, frogs and newts. Among the adders predators are hedgehogs, badgers, foxes, crows and herons. 

Grass snakes

Grass snakes are bigger than adders, up to one metre in length, completely harmless and are rarely seen. They have an olive-green background colour with black vertical bars along their flanks. 

Did you know?

  • The adder is Britain's only venomous snake
  • The grass snake is bigger in length than the adder
  • Hedgehogs will prey on adders