Scientific name: Natrix natrix
The grass snake is the largest species of British snake, and is identified by its olive green body and darkish spots or streaks on the flanks. However, colouration can vary. Grass snakes have a distinctive yellow and black collar behind the head and have round pupils.
They can often be confused with the adder which has a more thick-set body and a distinct zigzag down its back, and it also has a vertically slit pupil. The adder is venomous, whereas the grass snake is not. Adders are rarely found in gardens.
Grass snakes can also be confused with slow worms, which are not snakes but legless lizards and are much smaller, with a glassy grey/brown appearance.
Males can be told apart from females by a swelling at the base of the tail, and a longer tail in relation to the females tail.
Where to find them?
There are a variety of suitable places in gardens which you could find grass snakes. Compost heaps are often used as egg laying grounds due to their warmth which acts as a natural incubator. Garden ponds are used as foraging grounds for their food, as are any streams or ditches that may run through or close to your garden. Banks, mounds and rubble piles are used as areas to bask in, and they can also act as hibernation sites. Areas of short and long grass interspersed will often be used for foraging (long grass) and basking (short grass).
Role in the garden
The grass snake’s diet consists mainly of amphibians such as frogs, toads and newts, but they can be known to also eat small mammals, young birds and some fish.
The snakes natural predators are badgers, foxes, cats, hedgehogs and a number of birds. The snake has two tactics to dissuade certain predators from killing them – ‘playing dead’ and releasing pungent and foul-smelling substances from the anal gland.