Common Adder / Northern Viper  (Vipera berus).

The Common Adder, Britain's only venomous snake, is seen here coiled in its defensive stance and ready to strike. For more photos and information on Adders please visit the Adder pages on this website:

1)  Adders Page 1     2)  Adders Page 2     3)  Adders Page 3     4)  Adders Page 4 - (most recent)

In the UK we have three native snake species and one non-native snake that has established healthy breeding colonies at two different sites. These are:

Native:    Adder (Northern Viper),     Grass Snake,     Smooth Snake

Non-native:    Aesculapian Snake

The Grass Snake  (Natrix helvetica).

Grass Snakes are completely harmless to humans and feed mainly on amphibians and small fish when they can catch them. They will also prey on small mammals, young birds and even lizards occasionally.  The Grass Snake is Britain's longest native reptile and can occasionally reach sizes of up to 5ft in the UK and very occasionally stories of even 6ft specimens are heard but it is unlikely that any specimen of that size exists in the UK any longer. These larger Grass Snakes are more commonly found in warmer parts of Europe though. In the UK 2-3ft in length is the most commonly recorded length of adult specimens found. Any Grass Snake with a total length of 80+cm is usually female, and any Grass Snake with a total length of 110cm or more is always a female.

When talking about snakes, many herpetologists quote snake lengths as "STV" length. This means "snout to vent". Measurements are usually taken from the tip of a snake's nose to the opening of its anal glands at the base of the tail. This is a more accurate way of regularly monitoring a snake's length as snake's tails are often damaged or broken over the years especially after encounters with a predator.


Grass Snakes are Britain's only native egg-laying snake. The eggs need plenty of heat to hatch successfully so the female lays them in damp rotting vegetation. Because of this Grass Snakes are regularly found on allotments or in gardens with compost heaps as these provide an ideal spot for the Grass Snake to lay their eggs due to the heat generated by the rotting vegetation. The number of eggs laid usually varies from 10 - 40 depending on the size of the adult female. When clutches of eggs are first laid at the ovipositicula (egg-laying site) these eggs are soft and sticky and  can often be found stuck together in one large mass.

Grass Snakes are excellent swimmers and are just as 'at home' in the water as on land. If threatened the Grass Snake can disappear under water holding its breath for up to an hour to evade a predator. They will also actively hunt newts, frogs, toads and small fish in water. They are such competent swimmers that they have even been recorded crossing the sea from mainland Britain to small islands off the west coast on calm days.

Grass Snakes are found in various shades of green and brown colouration. Olive green is the term that best describes the most common colouration found. Melanistic (black) examples are very rare in the UK but they have been recorded at sites across the country. Malcolm Smith's book "The British Amphibians and Reptiles" makes reference to an albino specimen that used to live in Regent's Park many years ago. He also mentions a whitish specimen found in Bloxworth Heath in Dorset.

Male Grass Snakes are typically smaller than females both in length and girth.  Females also tend to have a larger more triangular-looking head and a more muscular jaw. The tails are also longer on the males and the male usually has a more distinct yellow collar than the female. This yellow collar can fade completely in particularly old Grass Snakes. Occasionally some specimens are born with this yellow collar completely absent from birth as with the example pictured above but this is quite rare in the UK. Collarless examples are more common on the Jersey Channel Island where Grass Snakes are considered their rarest native reptile and are fully protected by law. Grass Snakes were often previously referred to as the "Ringed Snake" or  "Ring-Necked Snakes" due to the yellow collar usually present behind the head.

It is believed by many that the yellow collar on Grass Snakes is a form of aposematic colouration to deter avian predators. An experiment was carried out using Plasticine models of snakes and proved that avian predators would indeed target melanistic specimens as oppose to typically coloured specimens with a yellow collar. The paper can be viewed here.

This female Grass Snake has a noticeably swollen stomach having just eaten an adult toad which weighed a third of the snake's total body weight! Digesting a meal of this size takes a huge amount of energy and this snake will need to lay dormant for 24hrs or more. Basking in the sun will speed up this process but during this period the Grass Snake is highly vulnerable to predators herself.

You can see how much this recently consumed mean has stretched the snakes body by the large gaps between the usually overlapping rows of scales.

Although very shy and easily scared off Grass Snakes are the most common snake in the UK to be found wandering into urban gardens. Grass Snakes are found across England and Wales and are found in small numbers in the very South of Scotland just over the border. (A fact that has only very recently been confirmed so not what you will read elsewhere!).

This photograph has been awarded "Highly commended" in the 2011 Marwell Wildlife Photographer of the year awards.

Although Grass Snakes are termed non-venomous they do possess Duvernoy glands (like rear-fanged venomous snakes) in their upper jaws that produce a very mild venom. The Grass Snake does not possess any fangs to deliver the venom to its victim though. Although this venom is very mild and is only found in small quantities in the Grass Snake's saliva it is not purposeless. The main diet of the Grass Snake is amphibians which when caught in the mouth of the snake will absorb this venom through their skin. This would help to subdue a struggling frog or toad.

If handled Grass Snakes may 'musk' the supposed predator.  They do this by secreting a foul-smelling liquid from their anal glands.  If this does not deter the potential attacker then the Grass Snake's next line of defence is often to feign death. They literally lay on their back with their mouth open and their tongue hanging out and pretend to be dead in a very theatrical manor. Obviously this will only deter predators that refuse to eat carrion and is not a very effective form of defence. The practice of feigning death is more common amongst larger Grass Snakes and the time that this display takes can vary from a few seconds to 30 minutes. During this display the Grass Snake will continue to keep an eye on you and if it catches you watching it closely it will take longer to recover.

A 2ft female Grass Snake "feigning death". Notice how tiny the teeth are.

Grass Snakes very very rarely attempt to bite when handled but they do occasionally hiss, and older, larger snakes may rise up in a threat display and occasionally pretend to strike with a closed mouth. I have experienced this with a male specimen that when handled, hissed loudly and continuously and struck at me repeatedly with a closed mouth.

I have heard of two first-hand accounts from people that have been bitten by Grass Snakes. In both incidents, the snakes in question were large female specimens found on egg-laying compost heaps. The result on both occasions, was a series of tiny pin-prick tooth marks that bled very slightly, very minor swelling to the hand with and a warm tingling sensation.


Grass Snakes are riparian meaning that they usually inhabit the banks of rivers, ponds and streams. They like still or very slow moving areas of water with vegetation hanging over the water from the banks. They will often bask on the banks partially covered by the foliage allowing them to disappear into vegetation or dive into the water at the first sign of trouble.



This 20 inch sub-adult female Grass Snake is gathering all the information she can about her surroundings by constant flickering of her tongue which she fully extends.



A paper published in June 2012 in Biodiversity & Conservation has revealed interesting facts about Grass Snakes and their preference for manure heaps to gestate their eggs. Following a relocation experiment it demonstrated that hatching success was highest (71%) when the eggs were placed in manure heaps. Compost heaps were not as effective with only 43% of eggs hatching successfully. Other placements of the eggs resulted in 0% hatching. This suggests that the Grass Snakes found the stable thermal conditions of the manure heaps more successful for hatching their eggs. Modern farming methods and the decline in large manure heaps stored on farms could be seriously detrimental to Grass Snakes.


This shot shows the Grass Snake in ideal habitat.  This south-facing slope has plenty of good vegetation along the river's edge as well as good clear spots that are exposed to plenty of sunlight where the snake can bask. There are also plenty of  mammal burrows which the snake can use as hibernacular during the winter. 

This adult Grass Snake was one of three seen swimming around the edges of a country park pond in Kent.






A 2ft female Grass Snake basking next to a wildlife pond in Kent.

Shortly before sloughing (shedding the old skin) snakes often spend more time basking to help with the process. This male Grass Snake clearly shows the typical blue-eyed tell tale sign of an imminent slough. 


 Smooth Snake (Coronella austriaca).   

Smooth Snakes are slender in build and are also the smallest of the British snakes usually growing to an average length of 45-60cm, occasionally  they reach 70cm with 80cm being the largest found. True to its name the Smooth Snake is the only native snake in the UK to have unkeeled scales giving it a very smooth feel when handled. Both the Adder and Grass Snake have a ridge or "keel" running down the middle of each scale. Smooth Snakes are brown-grey in colour and usually have a dark heart-shaped pattern on the back of the head. They also usually have a dark stripe that runs across the side of the head through the eye.

The Smooth Snake is Britain's rarest native reptile and is fully protected by law from being killed, harmed, or even disturbed. This makes it an offence to look for them unless you hold a licence to do so or you are in the company of a licence-holder who is authorised to do so.  Once common across the southern half of Britain they are now only found on heathland sites in Dorset and Hampshire, and a couple of sites in Surrey and West Sussex. Their total numbers are now estimated to be in the low thousands across the UK. This is due mainly to habitat loss as the Smooth Snake lives on heathland sites which have disappeared across the UK. Many of these sites are particularly vulnerable to fires. On some of these sites where the Smooth Snake is still found it is the most commonly encountered snake. The Smooth Snake is at the tip of its range in England as the average summer in Britain is only just long enough for the female to gestate her young. Unlike Grass Snakes the Smooth Snake is reported to be very reluctant to transverse unsuitable habitat to cross from one site to another. 

Smooth Snakes are reputedly very secretive in nature and spend most of their lives hidden underground out of sight. They don't bask as frequently as other British Snakes and they are often entwined amongst the base of heather plants where they are also very difficult to spot.  Occasionally some are seen basking openly though. Smooth snakes are non-venomous constrictors killing their prey by tightly wrapping it in the coils of their body. They feed mainly on other reptiles including young Sand Lizards which are Britain's rarest lizard and share many of the sandy heathland sites where Smooth Snakes are found. As well as lizards Smooth snakes will also eat smaller snakes and will even prey on young Adders. They will also prey on small mammals such as shrews and mice as well as young birds. Smooth snakes are also prone to cannibalism and  will even eat smaller Smooth snakes on occasion. This behaviour can be seen on a Facebook video here.


Smooth Snakes are viviparous giving birth to live young (usually 4-15) which are born in August or September. Melanistic (black) Smooth Snakes are incredibly rare in the UK with only two reports of sightings ever being recorded. The first record of a melanistic Smooth Snake in the UK dates from back in 1994 on a site in South-West Surrey. The last recorded sighting was of 2-3 specimens found on a site in Dorset in 2008.

Male Smooth Snakes are usually slightly shorter and slimmer than females but with longer tails. The females (photo above on the left) tend to be greyish with creamy coloured throats, and the males (photo above on the right) tend to be reddish-brown with orange throats.


Non-Native Species 

The Aesculapian Rat Snake  (Zamenis longissimus).

The fourth snake found in specific parts of the UK is the Aesculapian Snake. Although considered non-native to the UK there are two healthy well established breeding colonies of Aesculapian Snakes in Great Britain that have been in existence for at least 25 years. One is in Central London, England and the other is in Colwyn Bay, Wales. These long slender rat-snakes are one of Europe's longest and regularly grow to a length of 140-160cm In warmer parts of Europe they may even reach 225cm. These snakes are usually found across Southern Europe and use the same method of incubating their eggs as Grass Snakes using warm damp moist areas of vegetation such as hay piles and compost heaps to provide the necessary heat. Aesculapian Snakes are semi-arboreal meaning that they are excellent climbers and are equally at home high up in trees and bushes as they are on the ground. 

For more photos and information on these snakes visit this page on my website:    Aesculapian Snakes in the UK

The Corn Snake   (Pantherophis guttatus)

This Corn Snake was found in a suburban garden in Kent. Corn Snakes originally come from south-eastern United States but due to their passive nature they are one of the most popular snake species to be kept as pets in the UK. They usually grow to about 6ft in length and in the wild feed mainly on small rodents. In captivity they are prolific escape artists and it is not unusual for owners to find that their snakes have escaped into the wild if not properly secured. Many pet snakes are also deliberately set free every year when the novelty of ownership wears off and their owners no longer wish to commit the time and money needed to look after them. Because of this Corn Snakes and other non-native snakes are found in the wild every now and then here in the UK but it is very unlikely that Corn Snakes would ever be able to successfully breed due to our unsuitable climate needed for egg incubation.  In the wild they usually live for 6-8 years but in captivity they aften reach 23 years or more. The record life for a Corn Snake in captivity is over 32 years.


Ophidiophobia (the fear of snakes) is the second most common fear in the world.  See list here is a great on-line app that allows you to work out the total length of a snake from a photo, as long as you can accurately measure anything else in that photo.

All Photographs and text on this page are copyright protected and are the intellectual property of Jason Steel. Photographs were taken using:

 Canon 7D & 40D cameras and the Canon 70-300mm f/4-5.6IS, Canon 100mm f/2.8IS Macro,  Canon 15-85mm and Sigma 14mm f/2.8 Wide-Angle lenses.


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