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Adder pattern Add an Adder    
About Adders
Male adder Female adder
A male Adder A female Adder

Click on either of the images above for more Adder pictures (these may take some time to download)



Adders can be variable in colour, but typically the background colour differs in males and females. Males tend towards a grey, whitish, occasionally yellowish colour. The contrast with the black markings can make them appear almost silver. The females tend to be brownish with considerable variation of shade and occasional hints of red or yellow – although in the latter case always a much darker shade than the males.

Both sexes are similarly marked. Typically these markings are very pronounced and extremely easy to identify, consisting of a heavy dark zigzag pattern down the back with dark spots in rows on the flanks. At the back of the head there is a heavy “V” or “X” shaped marking and a dark band running from behind each eye. The young are coloured and marked much like adult females.

Although Adders are rather stocky snakes they are not very big, seldom exceeding 60 cms in length, the males being slightly shorter. The head shape is notably different from the other British snakes being rather broad and angular with an upturned snout.

The eyes are large and tend to be reddish in colour with a vertical pupil – again a feature unique to this species in this country.

The back pattern can vary in some individuals. With these variations there are occasional individuals that are not readily identifiable.


Black Adders

Black adder

Occasionally Adders are seen that are almost totally black in colour (melanistic). Although not very common, in some populations black individuals can be seen quite often. This appears to be a purely genetic trait rather than a consequence of their environment. Supposedly these animals are more venomous, but this is not the case in reality.

While in such animals the back pattern is somewhat obscured it is never completely absent as can be seen in the animals pictured below.

Black adder          Black adder

Click on either of the images above for more BlackAdder pictures (these may take some time to download)


  How harmful are adders?

The adder is the only British venomous snake, a fact which has earned it a dubious public image. Bites from adders are very rare, and the vast majority occur when a snake is picked up. Most reactions to adder bites are mild, but any bite should be regarded as potentially serious and immediate medical advice should be sought. In the last century, 12 human deaths in Britain have been attributed to adder bites (this compares with several deaths every year due to insect stings).

Bites to cats and dogs do occur, but rarely prove fatal. Vets and doctors in areas where adders occur are aware of the treatment required in handling bite cases, and effective treatment is now well understood. Occasionally people doing the gardening report being bitten by an adder, but not having seen the snake. These cases are more likely due to spider bites (there are several British species capable of delivering a painful bite) or pricking by thorns.

Other Snakes and snake-like animals

Occasionally, the following animals are mistaken for adders. Pictures are shown so that you can see the clear differences.


Slowworm. This grows to a maximum of 45cms (18 inches) and is usually much smaller. It has very smooth shiny scales. It is not, in fact, a snake, but a legless lizard and unlike snakes can close its very small eyes. You will often find it in gardens where it is a valuable ally as it loves to eat small slugs. This picture is of a female. The line down the back appears to be a zig-zag on close inspection and to start with a "vee" at the back of the head. But, as you can see, it is, in fact, nothing like an Adder.

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  Grass snake  

Grass Snake. This is our largest snake and can grow to over a metre (more than 3 ft) in length. The Adder's distinctive dark zig-zag line is missing. This photograph concentrates on the head and shows the pale yellow collar behind the head which is unique to the Grass Snake. In some individuals, especially youngsters, this collar can be quite bright yellow. Note also that this snake has a round pupil unlike the Adder's vertical one.

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  Smooth snake  

Smooth Snake. This is the snake most likely to be confused with the Adder. It is also our rarest and one you are very unlikely to see. Although it grows to about the same length as an adder it has a much slimmer body and a different shaped head. Although there is often a black mark at the back of the head it is not the same as the Adder's "vee" and the black markings on the back do not form a zig-zag as most Adder's do. Like the Grass Snake it has a round rather than vertical pupil.

Click on the picture for a larger view