Britain’s largest native snake 

In 2017 grass snakes found in England, Wales, and parts of Europe were discovered to be genetically distinct from their European cousins (Natrix natrix). So now they’re called Natrix helvetica or the barred grass snake, a nod to the striking black bars along their flanks. 

But whatever you call them, they’re unmistakable: Britain’s largest native snake, up to 1.5 metres long, they have a distinctive yellow and black collar just behind the head. They’re usually greenish-grey with pale undersides and dark stripes along the body, although they vary widely in colour. 

Born to swim, not to bite 

One of the biggest myths about snakes in Britain is that they’re dangerous. In fact, our native grass snake isn’t venomous at all. It hunts using stealth and speed, relying on surprise to catch prey like frogs, toads, newts, and even the odd small fish or mouse. And yes, they swallow their meals whole. 

You’re most likely to find them near freshwater, ponds, streams, ditches or basking on sunny compost heaps, edges of woodland, or long grassy margins. They’re surprisingly good swimmers and often spotted gliding silently across a lake or river with just their heads poking out. 

The great snake off 

Grass snakes are shy and would rather slither away unnoticed than confront a human. But if they’re cornered, they’ve got some impressive tricks up their scaly sleeves. They may hiss, puff themselves up to appear bigger, or even pretend to be dead – tongue lolling, body limp. As a last resort, they’ll release a pungent, garlic-smelling substance from their rear end to put off predators. Charming! 
 

Through the seasons 

From March onwards, as temperatures rise, grass snakes begin emerging from hibernation – the males usually making an early start. You might see them basking in the spring sun as they gear up for mating season in April and May. Come June or July, females lay up to 40 leathery eggs, ideally in rotting vegetation like compost heaps or manure piles. The warmth helps them incubate. 

By late summer, the eggs hatch into tiny replicas of their parents, and the young snakes must immediately fend for themselves. Sadly, they face many predators from foxes, badgers, pheasants and herons to hedgehogs and even domestic cats. 
 

Threatened by habitat loss 

Although still widespread, grass snake numbers are thought to be declining. 

Their reliance on healthy wetland habitats and abundant amphibians makes them vulnerable to habitat loss, water pollution and changes in land use. 

They are now protected by law in Great Britain and listed as a priority species under the Biodiversity Action Plan. By supporting your local Wildlife Trust you will be supporting conservation action on nature reserves and wetlands that help protect and restore habitat for grass snakes. 

Spotting one in the wild 

Seeing a grass snake in the wild can feel like a magical moment. You’re most likely to catch a glimpse in the early morning or warm afternoons between March and October. Watch out for their sinuous movement through water, or basking on compost heaps, logs, or grassy banks. 

They tend to return to favourite basking spots, so if you see one once, come back quietly another day – you might be lucky again. And don’t be surprised if you spot a delicate shed skin nearby: grass snakes shed at least once during the warmer months in a process called ecdysis. 

A symbol of wild Britain 

Often misunderstood or feared, the grass snake is a brilliant example of the wild creatures that live in our countryside and even our gardens, if we’re lucky. So the next time you hear a rustle in the undergrowth or catch sight of something gliding through your pond… look again. It might just be one of Britain’s most fascinating neighbours –  the beautiful, barred grass snake.

Thanks to Sophie Baker, Communications Officer for the Wildlife Trust for Bedfordshire, Cambridgeshire & Northamptonshire for this blog post.