Grass snake

The grass snake is Britain’s largest reptile and can reach up to 4ft long, and is the only UK snake that lays eggs too.  This snake is typically olive-green, with dark marks on its side, and yellowish with dark rectangular markings on the underside.  The grass snake has a characteristic black and yellow collar behind the head although the light part can be missing sometimes in older snkaes.  Male and female grass snakes are generally similar in appearance, although females are often larger; males can be identified by the presence of a swelling at the base of the tail and by the fact that they have longer tails relative to females.  The  juveniles are like mini adults and I was lucky to find 3 juveniles a couple weeks ago whilst monitoring reptiles in Flintshire.


They can sometimes be confused with the adders which have a thicker body and a distinct zigzag down their back, as well as having vertically slit pupils. The adder is of course venomous, whereas the grass snake is not. The grass snake has a distinct collar that looks like the letter M and also has round pupils.

The grass snake often pretends to be dead when threatened or move away very fast. When caught, the grass snake can hiss loudly and releases a foul-smelling substance from the anal gland. They can coil up, thrash about and pretend to strike, though they do not bite. Recently while on a reptile survey I was covered in this smelly substance…it wasn’t too unpleasant but it was extremely potent and I couldn’t wait to have a shower and wash all my clothes when I got home.

Grass snake are fast-moving, alert and very wary creatures. They bask in the sun after emerging in the morning in order to reach a high enough body temperatures so they are able to function efficiently and digest prey. During winter, the temperatures are too low and the grass snakes will find frost-free places such as deep leaf litter or rock piles in which to hibernate between October and  April. You will also found them under man made refugia too. These man made refugia of either corrugated metal or felt are usually put on nature reserves so both reptiles and amphibians can be monitored easily and populations assessed.


Courtship and mating takes place from April to June and around June-July about 20 eggs are laid in compost or manure heaps where the rotting vegetation creates warm conditions, acting like a natural incubator.  Hatching usually occurs 10 weeks after egg-laying, and the snakes escape from their eggs by chipping at the shell with an egg tooth, which is lost shortly after hatching.  Males can shed their skin twice a year, whereas females slough their skin once a year just before egg-laying.  I managed to find a sloughed grass snake skin recently and have put it in a display box with other nature items for reference. The detail on the sloughed skin is amazing. You can see the patterns of the skin and even where their eye was.


The grass snake is an active predator of frogs, toads and newts, although fish, small mammals and young birds may also be taken. They search for prey by sight and by smelling with their tongue, then grab their prey and swallow it alive. They are also strong swimmers.



Grass snakes are normally found in wetland habitats, where they have access to sunny basking areas and plenty of shelter. They may also be found in open woodland, rough grassland, gardens, parks and hedgerows too.


There are a variety of places in gardens were you could find grass snakes. Compost heaps are often used to lay eggs in due to their warmth. Garden ponds are used as foraging grounds, as are any streams or ditches that may run through or close to your garden. Log and rubble piles are used as areas to bask on, as well as act as hibernation sites. Areas of interspersed short and long grass will often be used for foraging (long grass) and basking (short grass).

Across Britain, snakes are disappearing because of a loss of reptile-friendly habitats, so in some areas, gardens are becoming an important habitat for grass snakes, particularly those with ponds and amphibians. As their natural habitat is lost and modified, the snakes are relying increasingly on gardens with favourable habitat to forage for food and for nesting sites. Snakes don’t damage your garden and they are not venomous and do not bite, so please don’t discourage them. You may not even realise you have them in your garden as they are shy, wary creatures.

Snakes have undergone widespread declines in the last century, and they are now protected by law against intentional killing and injury. I like to go out when possible to monitor and survey them on selected sites and help create reptile friendly habitats for them.  They are such beautiful creatures and all though there are no reported sighting in my local area for grass snakes I may still put a man made refugia out just to see; at the very least, the newts and toads will like hiding underneath it.




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