Adder (Vipera berus berus)

Page status: In review, Last update: 08-Feb-2007

English common names: Adder, Northern Viper, Common Viper, Common European Adder, Crossed Viper, Gad
Local names: Gwiber (Welsh), Neidr/Nadredd (Welsh), Naddyr (Cornish), Nathair (Gaelic)
Scientific name: Vipera berus berus

Title page adder (Vipera berus berus)

The Adder is the United Kingdom's only venomous snake and is widespread across Britain, although absent from Ireland and many offshore isles1.

It is a short snake, rarely exceeding 80cm (2.5 feet), with a heavy-set appearance. The body of the Adder is usually a brown or cream colour with a distinctive dark zig-zag pattern along its back. Body colour can be extremely variable from brick-red, to black in the melanistic forms. The Adder has red eyes with a vertical pupil. Although exceptional, individual Adders have been known to live for 30 years in the wild.

It is believed that the name 'Adder' is derived from the Old-English word nadder (Anglo-Saxon: nζddre) which means a twisting stream, reminiscent of the Adder's pose.

Identification  -  How to tell if you have seen an Adder


The largest Adders are 80cm (2.5 feet) in length (there are rare exceptions). If you see a snake longer than this, the chances are that it is not an Adder. Small size is not an indication of species, as the length of the Adder depends partly upon the age of the animal.

With the exception of melanistic (black) Adders, there is almost always a clearly defined dark zig-zag pattern running along the full length of the snake's body. (Melanistic adders also have this marking, but is can be difficult to see due to the poor contrast against the body colour). Usual body colours are cream or brown, but brick-red and black Adders are not uncommon.

Should you manage to get a view of the eye, it will be a red colour with a vertically slit pupil (unless the eye appears opaque and a blue/grey colour which happens just before shedding its skin). The Adder is the only wild UK reptile with a vertically split pupil (similar to a cat's eyes).

Serpentine male adder (Vipera berus berus)

The vertically slit pupil of the Adder is unique amongst UK reptiles.
(Ash, Surrey 2006).

Pre-slough eye of an Adder (Vipera berus berus)

Occasionally you may see an Adder, or other reptile with an opaque covering over its eye. This is perfectly normal and happens just before the animal sheds its skin.
(Ash, Surrey 2006).

Typical Adder ID characteristics (Vipera berus berus)

In this picture, you can clearly see the slit pupil, and the characteristic dark zig-zag along this Adder's back.
(Frensham, Surrey 2005).


The Adder's distribution includes almost the entire mainland of Great Britain, so unless a sighting occurred in Ireland, or on some of the more distant offshore islands, then it could be an Adder. Within England, the Adder is rare within the counties of Greater London, Nottinghamshire, Warwickshire, Buckinghamshire and Hertfordshire, however there is at least one known colony in each of these counties.


Adders rarely venture into gardens, unless the garden backs onto suitable habitat. If you should see a snake around a garden pond, it is most likely to be a Grass snake. Adders are creatures of dry heathland, woodland edges and chalk grassland. Any snake-like animal seen in compost heaps or verges is more likely to be a Slow worm.


Any healthy Adder is likely to see you before you see it, and glide silently away into the undergrowth. Adders will always move away from human presence, unless cornered or startled. A cornered Adder will inflate itself and hiss, maybe even strike out a couple of times to show it can defend itself. More usually it will move quickly away from any human, making very little noise, unless over dry leaves etc.

What else could it be?

The UK has only three native snake-like animals which could be confused with an Adder: These are the Grass snake, the rare Smooth snake and the Slow worm (which is in fact a legless lizard!).

Grass snake

The Grass snake is a fast-moving, alert snake which is often found in gardens. It is completely harmless to humans or pets. Grass snakes appear uniform in colour with no obvious zig-zag along the back, although dark spots are common. Grass snakes are absent from Ireland and Scotland, although widespread across England and Wales.
(Eelmoor marsh, Hampshire 2005).

Grass snake head portrait

The Yellow, cream or white collar is almost always present in Grass snakes, no Adder has such markings. Note the round pupil of the eye, compared to the vertical slit of the adder.
(Eelmoor marsh, Hampshire 2005).

Smooth snake

The rare Smooth snake has a restricted range in the UK, limited to Dorset, Hampshire, Surrey and West Sussex. It is a specialist of dry heathland habitat. There are markings along the back, although these are spots and not the heavy zig-zag of the Adder.
(Surrey 2006).

Smooth snake head portrait

The Smooth snake's black eye-stripe which more defined than that of the Adder. Note the round pupil and slenderness of the snake compared to an Adder.
(Surrey 2006).

Slow worm

The Slow worm is both common and widespread. It is often found in gardens, especially in, or close-by compost heaps. It is small (18 inches) slow-moving unless startled, and has smooth and metallic-like scales. This animal is a friend to gardeners, as it eats slugs and other garden pests.
(Eelmoor marsh, Hampshire 2006).

Slow worm head portrait

The Slow worm is a legless lizard, and not a snake at all! The Slow-worm's eyes have eyelids, which are absent in all snakes.
(Eelmoor marsh, Hampshire 2006).

Adult Adders in situ  -  Adult Adders as you might see them in the countryside

Male Adders emerge from hibernation before females. The first Adder sighting of each year is normally within a week of Valentine's Day (14th February)5.

Towards the end of April, the males will slough their dull hibernation skin revealing a fresh vivid moult5. The effect is similar to giving an old car a paint respray! Male Adders are smaller than females, with males rarely exceeding 60cm (2 feet) in length.

Reproductive female Adders emerge from hibernation about a month after the males emerge, in late April.  Females are larger than males and can grow to 80cm (31 inches).

Serpentine male adder (Vipera berus berus)

Male in serpentine form intertwined in heather sticks. Demonstrates classic male colouration and pattern.
(Brookwood, Surrey 2005).

Bracken-basking male adder (Vipera berus berus)

Male Adder blade-basking (flattened body) in an unusually exposed position on a Southern facing bracken bank.
(Ash, Surrey 2005).

Moss-basking male adder (Vipera berus berus)

Male Adder coiled on moss patch within heather. Deep moss provides the Adder with a ready escape option from predators.
(Frensham, Surrey 2005).

Coiled gravid female adder (Vipera berus berus)

Coiled female in typical basking pose. The distinct swelling about two-thirds along the body shows this female to be gravid (pregnant).
(Sheets Heath, Surrey 2005).

Ventrals of male adder (Vipera berus berus)

This female was basking on a pile of pine needles, several feet into tree cover, using a shaft of sunlight for basking while remaining relatively safe from predators.
(Ash, Surrey 2006).

Basking female adder (Vipera berus berus)

Typical basking spot. In direct sunlight, with sheltering cover on three sides.
(Ash, Surrey 2005).

Adult Adders in close up  -  Detailed photographs of adult Adders

Male Adders are most noticeable in the month of April, as they have just sloughed, so are brightly coloured, and are very mobile in search of a mate.  It is often possible to easily approach males at this time of year as they are less disturbed by human presence.

Female Adders are most noticeable during August and early September, when gravid (pregnant) individuals bask for prolonged periods to aid the development of their young.

Hunting male adder (Vipera berus berus)

Female Adder hunting in light cover. Note the red eye with a vertically slit pupil.  The Adder is the only wild reptile in the UK with a vertically slit pupil, all others have round pupils.
(Ash, Surrey 2005).

Ventrals of male adder (Vipera berus berus)

This image demonstrates the black ventral (belly) scales, typical of a male Adder. Other clues to this being a male animal are the tapered tail, and the clearly marked blotches on the lateral (side) forebody.
(Ash, Surrey 2005).

Flicking tongue of male adder (Vipera berus berus)

Adders can smell by 'tasting' the air with their tongue, the tongue is withdrawn and passes over the Jacobson's organ in their mouth which 'analyses' the sampled particles. Also note the keeling (ridges) on the scales of the forebody.
(Ash, Surrey 2005).

Alert female adder (Vipera berus berus)

Portrait in profile of the head and forebody of a female Adder. The vertical pupil can be readily seen, as can the characteristic eye-stripe.
(Eelmoor marsh, Hampshire 2005).

Head close-up of female adder (Vipera berus berus)

Close up of the head of a very old female Adder, demonstrating the orangey colour of the upper labials (lip scales). This particular animal was quite grumpy resulting in the camera lens needing a good clean to remove venom.
(Ash, Surrey 2005).

Ventral scales of female adder (Vipera berus berus)

Ventral (belly) scale colouration of a female Adder.
(Ash, Surrey 2005).

Adder Polymorphism  -  Colouration and marking variations for Adders

Adder colouration can be extremely variable. Brick-red Adders are not uncommon, and many sites have melanistic or black-Adders. One site in Anglesey even has a blue variation! Pale colourations include albino animals (very rare) or leucistic specimens (white animals with normal eye colouration).

Black adder dorsal surface (Vipera berus berus)

A widespread colour variation is the Black-Adder, a melanistic form. Even though the body colour is dark, the typical markings can just be seen.
(© Paul Smith - Hampshire 2006).

Blue adder (Vipera berus berus)

Although a blue tinge is often present for Adder which have recently shed their skin, this degree of blue is unusual. Several specimens from the Anglesey area exhibit this variation.
(© Axel - Anglesey, Wales 2006).

Orange female juvenile adder (Vipera berus berus)

Although this snake looks particularly orange in colour, it is a fairly usual colour for immature female Adders.
(Brookwood, Surrey 2005).

Sexual Dimorphism  -  How to tell if an Adder is a male or a female.

Viewed from a distance, the most likely way to determine the sex of an Adder is to observe the colour of the zig-zag pattern along its back.  Generally, males have a black pattern, and females have dark brown markings.  This is not 100% reliable as some variability occurs.  The tail shape of a female is distinctly shorter and tapers more severely than a male's, however some practice is required before the observer can quickly and reliably use tail shape as a discriminator.

The following rules of thumb can help to aid sexual identification:
  1. The dorsal (back) zig-zag pattern is black (or grey) for males, and brown for females.
  2. The main body colour for males is usually cream, whilst the main colour for females is brown.
  3. The female Adder's tail is shorter and tapers more obviously than that of the male.
  4. The ventral (belly) scales of the male are uniformly (or striped) black, those of the female are a lighter grey or mottled black.
  5. The labial (lip) scales of the male are black and white, whilst those of the female can be brown or orange.
  6. The lateral (side) forebody markings are darker and more evident in males.
  7. Females grow larger than males. Males rarely exceed 60cm (24 inches).
  8. Males have between 32 to 46 subcaudal (under tail) scale pairs, whilst females have between 24 to 38.
Gender comparison of adder1 (Vipera berus)

Male (right) and female coiled with young male approaching. Males have a black zig-zag whilst females' are usually brown. The cream body colouring of the males, compared to the brown of the female is very clear in this case.
(Crooksbury, Surrey 2006).

Gender comparison of adder2 (Vipera berus) Gender comparison of adder2 (Vipera berus)

Female tail (top) is shorter and tapers more severely than the tail of the male Adder (bottom).

Gender comparison of adder1 (Vipera berus) Gender comparison of adder1 (Vipera berus)

Note the heavier more predominant lateral (side) makings of the male (bottom) compared to the female (top).

Reproduction  -  Courtship, mating and defence of mates.

The best time to witness Adder courtship rituals is a fortnight either side of May Day (1st May).  Adders become extremely pre-occupied, and will often totally ignore the presence of a human observer. Males are very active in search of potential mates, and on finding an unguarded female, will circle her in a series of jerky movements, flicking his tongue over her body. This ritual allows the male to determine whether the female is receptive, and signals his intentions.  Mating is rarely observed, and can take upto two hours, usually in dense undergrowth.

After mating, the male will stay close to a female, 'mate-guarding' her to ensure that no rival males mate with her.  Any intruding males will be challenged, with both males moving parallel to eachother, 'sizing eachother up' before combat, where the males will intertwine, attempting to force the head of his rival to the ground.  This 'dance of the Adders' can last for several minutes, with a sudden climax when the defeated male shoots away, with the victor in hot pursuit.  The winning male will soon return to the female, either mating, or to continue mate guarding.

After mating, females take every opportunity to bask, aiding the development of their unborn young.  The females give birth to between 5 to 20 live young (unlike the Grass snake, which lays eggs) in late August or early September of between 15-20cm (4-6 inches) in length. Female Adders will not reproduce every year, once every two to three years is a fair average, as the females need this time to regain lost weight5.  Juvenile Adders are fully venomous and are independent soon after birth.

Suitor male adder (Vipera berus berus)

When a male approaches a possibly receptive female, he will circle her in a series of jerky movements, flicking his tongue over her body.
(Crooksbury, Surrey 2006).

Orange female juvenile adder (Vipera berus berus)

If a male approaches a female which is paired with another male the two males will intertwine, each attempting to force the head of his opponent to the ground. This is called the 'Dance of the Adders'.
(Crooksbury, Surrey 2006).

Young Adders  -  Photographs of juvenile Adders.

Adders bear around 8 live young of about 15-20cm (6-8 inches) from the end of August to early September. These young are independent at birth and add weight though a diet of lizards. They enter hibernation from the end of September to early November. Their markings are similar to adults, and these youngsters become sexually mature at about the age of four years.

'Juvenile' or 'neonate' refers to an Adder born within the year (prior to its first hibernation). 'Immature' refers to an Adder which has survived a hibernation, but is not yet sexually mature. (Herpetological Conservation Trust recording nomenclature).

Immature female adder (Vipera berus berus)

A young (18 month) Adder's markings are a minature version of the adult markings. This orange colouration is common for an immature female Adder.
(Brookwood, Surrey 2005).

Immature adder (Vipera berus berus)

A very young adder of about 6 inches (15cm) in length. Even at this young age, the Adder has a powerful vemonous bite.
(© Paul Smith - Surrey 2006).

Immature adder (Vipera berus berus)

A young, six week old, adder being expertly handled to demonstrate size. Never attempt to handle adders in this way unless you are experienced, you WILL be bitten!
(© Paul Smith - Surrey 2006).

Defensive Adders  -  Defensive behaviour of Adders, and Adder bites

The first form of defence of an Adder is always to flee.  Only when surprised, or cornered will an Adder strike, and will often emit a warning hiss before biting.

Around 100 people are bitten by Adders each year in the United Kingdom4.  This is an amazingly small proportion of people who visit the countryside.  Of these 100 people, most are men, who are bitten whilst trying to pick up an Adder3, a very bad idea! The Adder's bite is a serious health risk if envenomation occurs (about one in ten Adder strikes against humans are 'dry-bites'2, where no venom is injected).

Anybody unlucky enough to receive a bite should remain calm and seek professional medical attention immediately.  Never apply a tourniquet as this can restrict blood flow and cause permanent damage, however immobilising the limb is recommended, as it helps to prevent the venom from spreading. Paracetamol may be given to help with any pain, however do not attempt to remove venom from the bite area4.

Only 14 people have died from Adder bites in the UK since 18763, and none since 19754 (eight people died from insect stings in 2004 alone).  Some of these deaths were due to a severe allergic reaction to previous types of antivenin (the current Zagreb antivenom is successfully administered with antihistamine and hydrocortisone if such a reaction is suspected).  The vast majority of adults bitten by an Adder recover completely after a painful month or so, with no long-term medical effects. Children tend to recover faster than adults, recovering after only a week.3.

Dogs are at risk of receiving a bite if they startle a basking Adder.  Owners can minimise the risk of a bite, by throwing toys along paths and not into deep heather (keeping a dog on a lead is a surer way of keeping it safe in known Adder areas).  If a dog grabs a fleeing Adder it may receive a bite; owners should never attempt to remove an Adder from their dog's mouth by hand, as the terrified snake will be likely to strike.  Any dog which promptly obeys a 'drop' command is less likely to suffer a painful bite.

Defensive adder (Vipera berus berus) Figure of eight adder (Vipera berus berus)

Two Adders in defensive posture. The raised head gives good all-around visibility, and the figure of eight pose allows the Adder maximum strike range of about 30cm (12 inches).
(Ash, Surrey 2005).

Striking Adder 1 (Vipera berus berus)

Striking Adder. Adders will readily strike at an attacker if cornered or surprised. Their venomous bite can be very painful.
(© Paul Smith - Brookwood, Surrey 2006).

Adder Prey  -  The animals which make up the food of Adders.

An adult Adder may eat only 8 to 12 times per year. Being ectothermic (a more accurate term than cold-blooded) they have a very slow metabolism. Although the main prey of Adder is small mammals, like most snakes, they will eat whatever they can overpower. Less common food of Adders includes other reptiles, amphibians and nestling birds.

Although mainly active during daylight hours, Adders can hunt at night providing the temperatures are sufficiently high. The usual method for hunting involves an ambush technique where the prey is bitten, envenomated and immediately released, to prevent injury to the snake. The Adder will then track its prey, until it finds its dead or dying victim, which it then consumes, head first. Recent research suggests that vipers are capable of tracking the individual prey they have bitten, regardless of whether venom was actually injected, even in the presence of crossing scent trails of other individuals of the same prey species.

Bank vole, prey of adder (Vipera berus berus)

Bank voles form the basis of the adult Adder's diet of small mammals.
(Eelmoor marsh, Hampshire 2005).

Common lizard juvenile, prey of adder (Vipera berus berus)

Juvenile Adders are specialist feeders upon young (or even adult!) common lizards.
(Brookwood, Surrey 2005).

Pipit chicks, prey of adder (Vipera berus berus)

The chicks of ground-nesting birds, such as larks and pipits are also likely prey for Adders.
(Caesar's Camp, Hampshire 2006).

Predators  -  Animals which are known to prey upon Adders.

Research has shown that the zig-zag patterantion of the Adder is more likely to be a warning to predators that it can defend itself with venom (aposematism), than an asset to camouflage (crypsis). However, many animals are capable of preying upon Adders.

Adders also avoid predators by use of protective cover, and by using their senses of sight, hearing and smell. Although snakes have no ears, they are sensitive to ground vibrations, and have been shown to be able to hear airborne sounds through a mechanism called the 'skin muscle bone' response. Adder's eyesight is poor, however they respond well to movement and objects silhouetted against the sky.

Heron, predator of adder (Vipera berus berus)

Grey Heron (Ardea cinerea)
(Farnham, Surrey 2006).

Buzzard, predator of adder (Vipera berus berus)

Buzzard (Buteo buteo)
(Ash, Surrey 2006).

Pheasant, predator of adder (Vipera berus berus)

Pheasant (Phasianus colchicus)
(Geddington, Northants. 2006).

Birds are probably the main predator of adult and juvenile Adders. Herons, raptors (birds of prey), corvids (crow family) and pheasants pose the greatest threat.

Hedgehog, predators of adder (Vipera berus berus)

European Hedgehog (Erinaceus europaeus)
(Farnham, Surrey 2006).

Polecat, predator of adder (Vipera berus berus)

European Polecat (Mustela putorius)
(Snowdonia, North Wales 2006).

Smooth snake, predator of adder (Vipera berus berus)

Smooth snake (Coronella austriaca)
(Verwood, Hants. 2005).

Mammals and other reptiles prey upon Adders from ground-level. Mammals such as fox, badger and even hedgehogs have been known to prey on Adders. Animals such as mink, polecats and stoats are also likely culprits. Smooth snakes will eat young Adders of upto 30cm (12 inches) length.

Adder Distribution  -  Where Adders are present in the United Kingdom.

The Adder is widespread across Great Britain, but is absent from many of the offshore islands, and does not occur within Ireland. Notable exceptions to the range of this snake include part of the Midlands, Merseyside area and Greater London, probably due to high human population densities of these regions.

adder (vipera berus) distribution in the united kingdom

The red areas show the distribution of Adders in the UK.

Adder Habitat  -  Pictures of typical habitat for Adders.

Adders can be found in a wide variety of habitat types.  Although not normally a species which can be found in urban gardens, they can occur where gardens back onto fields or heathland.  Roadside verges, railway embankments and salt marshes are known to support good populations of Adder.

The underlying geology plays a large role in the distribution of the Adder.  Adders are more likely to be found on either sand and gravel or chalky soils; conversely they are rarely found on wetter clay soils.  This is reflected in the preference of the species for drier habitats, such as heathland and chalk scrub.

Heathland, habitat for adder (Vipera berus berus)

Dry heathland is superb Adder habitat. Best locations have good ground cover with a mosaic of clear patches for basking.
(Ash ranges, Surrey 2005).

Woodland edges, habitat for adder (Vipera berus berus))

Adders are often present in woodland. They prefer the woodland edges, where basking opportunities are greatest. Forest rides, where good cover at ground-level is in direct sunlight are ideal locations.
(Ash woods, Surrey 2006).

Chalk Grassland, habitat for adder (Vipera berus berus)

Chalk grassland can be perfect habitat for Adders. The abundance of small mammals ensures a food source and dense tussocks provide shelter for thermoregulation, cover from predators and hibernacula.
(Farnham, Surrey 2006).

Hibernacula  -  Places where Adders hibernate over winter

Adders require temperatures in excess of 6°C with sunshine in order to generate the energy required for activity. Over the Winter months (November to February) Adders hibernate. Hibernation is a state of torpidity where the Adder conserves energy by slowing its heartbeat and metabolism. It is quite possible for Adders to emerge on particularly sunny and warm winter days. The places where Adders hibernate are called hibernacula.

Hibernacula are usually located underground, within sunny, south-facing slopes, tree-root systems, dense tussocks, log-piles or embankments, on well-drained soils. They must provide protection from frost and predators, and must not flood.

Heathland, habitat for adder (Vipera berus berus)

Log-piles provide protection from the elements and larger predators. To make this an ideal hibernacula, it should be covered with earth, which would provide better protection from frost.
(Crooksbury, Surrey 2006).

Hibernation site for adder (Vipera berus berus)

This gorse bush summits a sandy south-facing slope. Its root system mingles with rabbit burrows, and provides an ideal hibernaculum for around 20 adders which use this area. The bush itself offers protective cover to emerging Adders.
(Frensham, Surrey 2006).

Adder Calendar  -  What Adders are doing and when.

The earliest Adder sightings each year are the first males to emerge from hibernation in mid-February. Most males will have emerged by mid-March. The reproductive females tend to emerge at the end of April, although non-reproducing females may emerge as late as mid-May (when hunting conditions improve).

Courtship occurs at the end of April or early May. Shortly after courtship, the males, which have been concentrated around the hibernacula area (waiting for female emergence) disperse to better hunting grounds. The reproductive females remain close to hibernacula for the entire year. Emerging non-reproductive females will also disperse to hunting grounds shortly after emergence.

Gravid (pregnant) females will give birth towards the end of August. All Adders return to the hibernacula areas by mid-September, returning to hibernation by the end of October.

Activity JanFebMarAprMayJunJulAugSepOctNovDec
Sighting Opportunities:   
Males at hibernacula:     
Male dispersion:   
Mating rituals:   
Gravid females:   
New-born Adders:   
Females in hibernation:   
Males in hibernation:   

Adder Legal Protection  -  How the Adder is protected under UK law.

Acts of Parliament:

Adders are protected under the Wildlife and Countryside Act (WCA) 1981 within England and Wales, by the Nature Conservation (Scotland) Act 2004 in Scotland and by the Wildlife (Northern Ireland) Order 1985 within Northern Ireland. Protection offered by these acts are similar, but there are some important differences.

Schedule 5:

Schedule 5 of the WCA lists all wild animals which are protected by UK law. Adders are listed within Schedule 5, with the caveat that only Section 9(5) of the act (Sale) applies to them. In 1991 the act was amended [WCA 1981 (Variation of Schedule) Order 1991] to include protection from intentional killing and injury under Section 9(1). Taking Adders from the wild is not prohibited by this act, although the Dangerous Wild Animals Act 1976 would apply to captive Adders.

Legal protection of the adder (Vipera berus berus)

The following table outlines the protection given to Adders under the laws of the United Kingdom:

Summary of the legal protection for Adder (Vipera berus) under UK law
Issues: England Scotland Wales Northern Ireland
Taking from the wild. DWA(1976)
Species not present
Intentional killing. WCA(1981) Sec.9(1)
NC(S)A(2004) WCA(1981) Sec.9(1)
Species not present
Reckless killing. None NC(S)A(2004) None Species not present
Intentional injury. WCA(1981) Sec.9(1)
NC(S)A(2004) WCA(1981) Sec.9(1)
Species not present
Reckless injury. None NC(S)A(2004) None Species not present
Offering for sale. WCA(1981) Sec.9(5) NC(S)A(2004) WCA(1981) Sec.9(5) Species not present
Disturbance in the wild. None None None Species not present
Damage to place of shelter. None None None Species not present
Destruction of habitat.
(due to development)
PPS9(2005) NPPG14 PG(W)PP(2002)
Species not present
Release into the wild. None None None W(NI)O(1985) Art.15
  • (VoS)O(1991)
  • DWA(1976)
  • NC(S)A(2005)
  • NPPG14
  • PG(W)PP(2002)
  • PPS9(2005)
  • TAN(W)5(1996)
  • W(NI)O(1985)
  • WCA(1981)
  • ZLA(1981)
  • (Variation of Schedule) Order 1991
  • The Dangerous Wild Animals Act 1976
  • The Nature Conservation (Scotland) Act 2004.
  • National Planning Policy Guidelines 14: Natural Heritage
  • Planning Guidance (Wales): Planning Policy (2002)
  • Planning Policy Statement 9: Biodiversity and Geological Conservation 2005
  • Technical Advice Note (Wales) 5, Nature Conservation and Planning (1996)
  • The Wildlife (Northern Ireland) Order 1985
  • The Wildlife and Countryside Act 1981
  • Zoo Licensing Act 1981
  • Adders would gain additional protection if this activity was prohibited by law.
  • Appropriate legal protection is provided.

Adder Conservation  -  Conservation status of the Adder
Conservation Status of the Adder

National Status:

Widespread, Threatened, Declining.

Highest Risk Counties:

Localised, Endangered, Declining.
(Greater London, Buckinghamshire, Hertfordshire, Warwickshire, Nottinghamshire).

Estimated National Population:

65,000 breeding pairs (declining).

The Adder's conservation status within the United kingdom is complex, depending upon local geography.

The Adder is widespread, with populations existing in all British counties, but is locally rare in some of these counties. Particular examples of local rarity include Greater London, Buckinghamshire and Hertfordshire. Underlying geology, human pressure, developments and conversion of suitable habitat into arable land are all factors contributing to the rarity of Adders in these counties.

There is strong anecdotal evidence to suggest that population of Adders is falling across the United Kingdom6. Some projects have been started to attempt to demonstrate whether this effect can be proven through objective analysis. Such projects include 'Make the Adder count' and 'Add an Adder'.

Many factors may contribute to the decline of the Adder. The table below outlines some of the believed causes:

Risks to Adder Conservation




Risk level


Lack of protection due to unknown populations' existence

Medium? High High Comprehensive survey.
(NARRS will provide a key element).
Habitat destruction High High High Provide protection under WCA 9(4)a
'Reckless destruction of shelter'
Encourage sensitive agriculture & forestry practices. E.g. Countryside stewardship.
Habitat management& restoration projects.
Enable Adder presence to be a major factor in site protection (E.g. SAC/SSSI)
Population isolation
(Gene-pool degradation)
Medium High High Establish habitat corridors between populations.
Novel-allele introductions.
Human disturbance High High High Provide protection under WCA 9(4)b
Negligent relocation Low High Medium Provide protection under WCA 9(1)
'Taking from the wild'
Human persecution Low Low Low Encourage Adder-friendly Public Relations
Enforce existing protection, WCA 9(1).
Non-disclosure of Adder sites.

Spotting Adders  -  How to see Adders in the wild

The best way to spot Adders is to determine a place where they are known to exist. This may be a local heath, common or even a nature reserve. Most areas of public-access countryside will have an appointed warden or conservation officer. Check your local council webpages to find who this is, and ask them where the best places are to spot Adders. Another useful source of information is the local Amphibian and Reptile Group (ARG). Be prepared for people to be secretive about Adder sites, as human persecution is, sadly, still a threat to Adders.

Observing reptiles in the wild can be difficult, and lack of sightings after hours of effort is usual for beginners, and can sap the initial enthusiasm. Knowing Adders are present in an area will help morale, and you can use a known site to hone your skills.

Once you have found a site, you must next decide whereabouts on the site is the best place to look. Adders require good dense ground cover, where they can hide from predators, yet also require sunny spots for basking. Adders tend to prefer higher (drier) ground in Spring and Autumn, and will readily adopt dips on a hillside as protection from the wind. South facing slopes are preferred, as sunlight will fall on these areas for more of the day.

Adders are very shy animals and will disappear into cover silently as soon as they detect your approach. Walk slowly and lightly, as ground vibrations can be picked up by Adders at a considerable distance. Pause occasionally to scan the edges of undergrowth. Walk with the sun behind your back, so you are looking at the undergrowth along your shadow. This way you will be looking into sheltered basking spots, rather than over undergrowth which obscures sunny positions. Look at the edges of good ground cover (ideally a mixture of deep moss and heather), in direct sunlight.

Although Adders are active in conditions as cold as 6°C, probably the best temperature range for spotting Adders is between 9°C and 19°C (48-66°F). Better days will have intermittent cloud cover, as continual sunshine allows the Adder to warm more quickly, and to bask less frequently, and the best chance of spotting Adders is when they are basking. Choosing a morning after rainfall the previous night provides even better chances for spotting Adders, as the dampness in the ground will cool the snake, such that it has to bask to gain the required energy for the day's activity.

Looking at cover close to your feet means that you would have to get very close to an Adder without it spotting you first. Its best to scan the ground-cover at a distance of at least 12 feet (4m) although further is better, scanning ahead and closer alternately, as Adders have excellent camouflage. If possible, walk such that any wind is blowing from the direction you are walking towards, as Adders have an excellent sense of smell, and could otherwise detect your presence.

If you are lucky enough to spot an Adder, remain motionless, and if possible crouch, very slowly, to the ground. Adders are very sensitive to objects moving against the sky, as most of their predators are birds. If the Adder moved into deep cover, and providing it was not unduly disturbed, if you remain motionless, it is likely to reappear within 5 minutes to the same spot to continue basking.

Heathland, habitat for adder (Vipera berus berus)

A fairly typical basking position for an adult male Adder. As usual, thick cover is close by the basking spot, in this case a gorse thicket.
(Hazeley Heath, Hampshire 2006).

Chalk Grassland, habitat for adder (Vipera berus berus)

The reward for hours spent searching for Adders can be the observation of beautiful animals such as this adult female, who was gently caught and posed for this picture.
(Ash woods, Surrey 2005).

Woodland edges, habitat for adder (Vipera berus berus))

This male Adder has found a last shaft of sunlight for basking as evening sets. This demonstrates how Adders are drawn to direct sunlight.
(Ash woods, Surrey 2006).

Adder Sightings  -  What should I do if I see an Adder?

If you manage to spot an Adder, do not approach it too closely. You are perfectly safe from an Adder if you provide it an escape route into ground cover.

As mentioned in the conservation section above, it is vital to collect evidence of the occurrence of Adders in order to provide the evidence necessary for their long-term protection. If you have seen an Adder you can help by reporting when and where. There are far too few professional and volunteer surveyors to adequately cover the United Kingdom, so reptile conservation organisations are heavily dependant upon sighting reports by members of the public. Your sighting record is important!

You can report your Adder sighting online at: RAUK online sighting report. Your records will be passed onto your local recorder, and the evidence will help with the Adder's conservation.

The Herpetological Conservation Trust are running a project to help us understand where Adders are and where they have been in the past. They are looking for both new and old records, but especially recollections and stories of historical colonies and sightings. If you remember a place where you have seen Adders, or have been told of a place where Adders used to be; please visit Add an Adder and share these experiences, at the same time helping the Adder's future.

Female adder (Vipera berus berus)

Female Adder moving between cover. It is rare to see an Adder this exposed, as they become easy prey for avian predators.
(Eelmoor marsh, Surrey 2005).

Female adder (Vipera berus berus)

A relaxed female Adder basking adjacent to good protective cover.
(Hazeley heath, Hampshire 2006).

Adder Links  -  Additional cyberspace information concerning the Adder.

Credits  -  Appreciation of the people who have contributed to this web page.
  • Gemma Fairchild for providing the UK's best herpetofauna (reptiles & amphibians) forum (RAUK).
  • The members of RAUK for their informative views, advice and permission to use particular images.
  • Tony Phelps for his expert technical review of this page. - Status: In review.
  • Paul 'SNAKE' Smith for supplying many of the images featured.
  • Chris Gleed-Owen of the HCT for his continued support and providing my scientific focus.
  • Sarah, for aesthetic review, and her patience while I was constructing this page.

All images and content © Steve Langham unless stated otherwise.
Status: In review.  Last Update: 08-Feb-2007 9:57