The grass snake Natrix natrix or more aptly named water snake is a non-venomous snake found throughout the UK and Europe.
The largest of our three native snakes, it can grow over 1.5m in length with the females being larger than the males.
A grass snake recently photographed by Darren Harries.
They're normally olive green or brown in colour with a characteristic yellow collar behind the head. The undersides are paler white with distinctive blocks of black.
Grass snakes can be tricky to spot due to their speed, agility and camouflage and are one of the few animals that will fake death, becoming completely limp if cornered.
Another defensive technique they use is to excrete a foul smelling liquid from their anal glands which apparently takes a long time to remove from your hands - should you be tempted to pick one up.
Like most snakes, you have to be extremely lucky and patient to spot one, as they will invariably slither away at the slightest vibration as you approach.
Grass snakes are excellent swimmers so your best chance of seeing one is actually when it's swimming in water or curled up in a pond hiding under foliage near the bank.
A swimming grass snake by Rat Salad.
Grass snakes prefer being close to water where they prey upon frogs, toads, small fish and the occasional small mammal or bird.
As Britain's only egg laying snake, a favourite haunt is in garden compost heaps which provide the perfect conditions for incubating their eggs in.
Grass snakes eggs will lay up to 40 eggs which require temperatures between 21-28 degrees with plenty of humidity.
Grass snake by Dave Hill @ DEFRA
After about 10 weeks the young snakes emerge in early autumn but few reach adulthood, becoming prey to other animals and as a result of this and loss of habitat, these snakes are now in decline.
The head markings on the snakes are unique like a fingerprint and can be used to identify individuals age, sex and distribution
If you do happen to find a grass snake in your garden then don't panic, they're completely harmless and you're incredibly lucky to have one.