There are three native snakes in the UK: grass snakes, adders and smooth snakes. If you’re by our canals and rivers, you’re most likely to spot the shy grass snake – a pro swimmer and water lover.
Grass snake
Identifying native UK snake species
Snakes are reptiles from the Serpentes suborder with long, thin, forked tongues. They’re identified by their lack of limbs, eyelids or ear openings. There are three main native snake species in the UK: the grass snake, the venomous adder and the smooth snake.
Grass snake
Grass snakes are the snake you're most likely to see near canals and other wetland areas. Grass snakes are often found by water, where they hunt amphibians and fish, but you might also see them in grassland, gardens and other habitats across the UK.
Grass snakes are greenish in colour, with a yellow and black collar, pale undersides and dark markings on their side. They can grow quite large – sometimes over a metre in length.
Grass snake
Are grass snakes dangerous?
Grass snakes are non-venomous and harmless to humans. If threatened, these shy snakes sometimes play dead by dramatically tossing their head back and lolling their tongues. If caught, they release a foul odour from their anal gland.
Although adders are more common in heathlands, moorlands and woodlands, they can occasionally be found near bodies of water. The adder is the only venomous snake native to the UK, but they are generally shy, and bites are rare.
Adders are grey in colour with a distinctive dark zig-zag pattern along their back with a ‘V’ or ‘X’ marking on their heads. Males are silvery in colour, while females might be more reddish-brown. Compared to grass snakes, adders are small, reaching 60-80cm.
Adder
Smooth snake
The smooth snake is the rarest native UK species and is mostly found in southern England, particularly in heathland habitats. They prefer to hide under stones and logs than bask out in the open. It is less likely to be seen near canals compared to grass snakes.
Smooth snakes are similar in appearance to adders, with slender bodies and less well-defined dark markings along their backs. They’re grey or dark brown and reach 60-70cm.
What’s the difference between snakes and slow worms?
At first glance, these limbless reptiles are easy to mistake for snakes in the UK. However, slow worms are not true snakes. They're much smaller than snakes, with a golden tinge to their smooth grey skin. Their heads are the same width as their bodies, making them distinct from the snake’s wider heads
Slow worm, credit Roger Key
Unlike snakes, slow worms have eyelids and can blink. They also have a detachable tail that can break off as a defence mechanism to escape predators, which will later regrow (though it never looks quite the same as the original).
How do I spot a snake in the UK?
Grass snakes are shy and quick to retreat from humans. They can be found in damp habitats, and you might see one on our towpaths or swimming across the canals. However, they can be hard to spot as they often stay hidden in the undergrowth.
