An adder coiled up

The adder (Vipera berus) is the UK's only venomous snake. Image via Wikimedia Commons (CC BY-SA 3.0)

Should we be scared of British snakes?

During the summer months, snakebites are more often reported across Britain. Discover why our native reptiles seem more volatile when temperatures warm up.

There are very few dangerous animals living in and around Britain. Although the sight of a snake might be terrifying to some, species found in the wild are rarely cause for concern.

Patrick Campbell, Senior Curator of Reptiles, explains why there is little reason to be scared of the snakes slithering through the countryside this summer.

Which British snakes are dangerous?

There are three species of snake native to Britain plus a fourth, non-native species. Three of these are completely harmless - only the adder (Vipera berus), a native reptile, is venomous.

But Patrick says, 'Generally speaking with the adder, you're not going to die from a bite.

'The bites tend to occur on the feet and ankles because people are exploring woodlands or heathland habitats and disturb them whilst walking. It's a defence mechanism - they're not going to come out and attack humans just for the sake of it.'

Some people may be bitten on the hand, but this is easily avoided by not picking up live snakes. 

An adder

Adders have a distinctive 'V' or 'X' marking on the top of their head © Thomas Brown via Flickr (CC BY-NC-SA 2.0)
 

'There have been a few incidents over the years, but for those who are in good health, you're not going to die from a bite. It will hurt and swell for a few days and you may have feelings of nausea and dizziness. Some who may be less fortunate may suffer an allergic reaction, but it generally isn't going to kill you.

'Children, the infirm and the elderly are most at risk.'

Fatalities from adder bites are exceptionally rare. The last in Britain occurred in 1975, when a five-year-old was bitten on the ankle in Scotland. Between 1950 and 1972 there was only one death caused by an adder bite across England and Wales.

Bees and wasps are more dangerous, causing 61 deaths over the same period.

For those who see a snake in the wild in Britain, Patrick says, 'The best advice would be: don't aggravate it. It's safe to observe them respectfully from a distance, but just don't go picking them up and they will leave you alone.

'There's nothing much to worry about. An adder won't chase you - there are stories, perhaps fanciful, of black mambas in Africa pursuing people, but the adder is not like this. It is not an aggressive snake, but quite shy and reclusive.

'However, in any case of suspected adder bite, immediate medical attention is needed, primarily to avoid infection around the wound. Antivenom is rarely needed but should be considered in severe cases.'

An adder

It is safe to observe British snakes from a distance, but they should be left undisturbed © Thomas Brown via Flickr (CC BY-NC-SA 2.0)
 

How to identify an adder

British snakes are usually solitary, shy animals that prefer to flee than fight. Adders are mainly found on heathlands, commons and woodland. More bites occur in the summer as British snakes hibernate through winter, when people are also less active and wearing heavier clothing and footwear.

The body temperature of snakes is regulated externally by sunning or retreating to cool. They need to be warm in order to be active.

'You often have to upturn logs and discarded metallic objects, which are good conductors of heat, to find them,' explains Patrick.

'They tend to favour hiding under things for safety, to keep warm or to escape the heat - unless they're out basking directly in the Sun. But if you find them, they'll often slither away rapidly and are likely to strike out only if provoked or picked up.'

Adders, also known as European vipers, have distinctive features that make them identifiable next to other British snake species.

Adders have stocky bodies, reaching a maximum length of approximately one metre. They vary in colour: males are usually grey and females reddish, although there are some that are entirely black (melanistic form).

They have a distinctive, darker zigzag pattern down the middle of their backs and a clear V or X marking on the top of the head. These snakes have a slit pupil (similar to a cat's) instead of a round one. They also have keeled scales - rather than being smooth, they have a raised ridge down their centre. 

An adder

Adders have a distinctive zigzag pattern running down the full length of their back © Thomas Brown via Flickr (CC BY-NC-SA 2.0)
 

Victims of a snakebite should seek immediate medical attention and try to remember a description of the snake seen to help medical professionals identify the species - but don't try and catch it.

Patrick says, 'Using a tourniquet to isolate the bite to some may feel sensible but in actual fact will probably only make matters worse. It will lead to the venom concentrating in one part of the body and could end up destroying  the flesh in that area.

'It's better not to use a tourniquet and to just immobilise the affected limb with a splint or sling for an adder bite - it may be different in the case of a more dangerous snake attack abroad.'

What other reptiles are found in Britain?

Two other species of snake are native to Britain: the grass snake (Natrix helvetica) and the smooth snake (Coronella austriaca). These are both non-venomous.

Grass snakes are the largest in Britain, reaching up to approximately 1.3 metres. They have a round pupil and have a green back with dark bars. These snakes have a black and cream or white collar at the base of the head and are also proficient swimmers.

A grass snake

Grass snakes have a white or cream and black collar at the base of their head © Thomas Brown via Flickr (CC BY-NC-SA 2.0)
 

Smooth snakes are very rarely encountered, confined to the heathlands of Dorset, Surrey and Hampshire. They have similar colouration to the adder, but the dark pattern on their back is not as distinctly zigzagged as the venomous snakes. Additionally, smooth snakes have polished (unkeeled) scales and a round pupil with a golden iris. 

A smooth snake

The smooth snake has less distinctive markings on its back than the adder © Thomas Brown via Flickr (CC BY-NC-SA 2.0)
 

Britain's fourth species of snake is non-native and has two known populations, in North Wales and in the Camden area of London. These Aesculapian snakes (Zamenis longissimus) are also non-venomous and feed on rodents.

An aesculpian snake in a tree

Aesculpian snakes are not native to Britain, but there are two known populations of them in the wild © Christoph Leeb via Wikimedia Commons (CC BY-SA 3.0)
 

Slow worms are often mistaken for snakes but are actually a type of legless lizard. The quickest way to tell a snake from a slow worm is to see whether the animal blinks. Lizards have eyelids, snakes don't. These reptiles vary in colour from grey to bronze.

Patrick says, 'In my experience, slow worms tend to be far less elusive than snakes in the wild. They are often found in gardens - I've found a dead one in my own back garden recently. They are more often confused with worms than with snakes because they don't have large, imposing scales which overlap each other. They're smooth to the touch, and most tend to be quite small compared to the snakes found here. '

A slow worm

Slow worms are often mistaken for snakes © Edaen via Wikimedia Commons (CC BY-SA 4.0)
 

In addition to snakes and slow worms, there are two other reptile species found in Britain: the sand lizard (Lacerta agilis) and the common lizard (Zootoca vivipara). Britain is also home to a number of frog and newt species.

If you are bitten by a snake:

  • seek immediate medical attention
  • remember the shape, size and colour of the snake
  • do not try and catch the snake
  • do not try to suck the venom out of the bite
  • do not apply pressure bandages or tourniquets around the bitten limb

Visit the NHS website for more native and exotic snakebite advice.