Snakes found in Great Britain

There are three species of snake that are native to Great Britain, these being the adder, the grass snake and the smooth snake. The slow-worm is often mistaken for a snake but is actually a legless lizard.

Adder (Vipera berus)

This is the only venomous snake that is found in Great Britain (it is absent from the whole of Ireland). The venom is used for catching its prey, mostly mice and voles, but it is not powerful enough to do much harm to humans. Adders are in any case very timid and are likely to move away from people rather than towards them.

Adders (also known as vipers) are usually grey or brown in colour with a characteristic zigzag pattern on the back and a V-shape on the back of the head. Males grow to about 60 centimetres (24 inches) long and females can be longer.

They inhabit heaths, moors and open hillsides and are sometimes found in sand dunes. Shed skins are a sign that adders are likely to be around. They often bask in groups in early spring; they prefer gentle warmth to the full heat of the midday sun.

Male adders emerge from hibernation in February or March, with females appearing a little later. The young are born fully-formed (i.e not hatched from eggs) in late summer and take up to three years to reach maturity. Female adders usually become pregnant only every two years.

Grass snake (Natrix natrix)

Grass snakes (see picture) are larger than adders, with females growing to 120 centimetres (48 inches) in length (males are smaller). They are light green in colour with black bars on the flanks and dots on the back.

They inhabit damp grass and ditches and the banks of ponds and streams. They are found throughout England and Wales apart from the far north-west of England. They are absent from Scotland and Ireland.

Grass snakes are entirely harmless to humans and most animals, their prey consisting of frogs and other amphibians.

They emerge from hibernation in April, after which courting and mating take place. Female grass snakes may travel a long distance (up to a mile) to find a suitable place to lay their eggs, this being somewhere warm such as a compost or muck heap or a haystack. Many females may choose the same site, so hundreds of young grass snakes may hatch at the same time, which will usually be in August or September.

Young grass snakes provide ready meals for birds, hedgehogs and badgers.

Smooth snake (Coronella austriaca)

This is by far the rarest of the three British snake species, being found only on the heaths of Dorset, Hampshire and Surrey. It is a protected species, the continued future of which is by no means certain. It is not easy to spot, especially as it tends to bask underneath warm stones rather than in the open.

The smooth snake grows to 60 centimetres (24 inches) long and is slimmer than the adder. It can be any colour from grey to reddish brown with dark spots down the back.

Smooth snakes prey on lizards and small mammals. As it is neither venomous nor a constrictor, it holds its prey in its coiled body so that it can get it into position to be swallowed head first.

Mating takes place in May and up to fifteen young are born in August or September. The young are delivered in a membrane that is easily broken. Smooth snakes are self-sufficient from birth.

© John Welford