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Vipera berus
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Common European adder
Benny Trapp Vipera berus.jpg
Conservation status

Least Concern (IUCN 3.1) common adder 1 common adder
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Genus: Vipera
Species: V. berus
Binomial name
Vipera berus
(Linnaeus, 1758)
Vipera berus distribution.svg
Synonyms
Species synonymy
Vipera berus, the common European adder common adder 3 common adder or common European viper, common adder 4 common adder is a venomous snake that is extremely widespread and can be found throughout most of Western Europe and as far as East Asia. common adder 2 common adder Known by a host of common names including common adder and common viper, adders have been the subject of much folklore in Britain and other European countries. common adder 5 common adder They are not regarded as especially dangerous; common adder 3 common adder the snake is not aggressive and usually bites only when really provoked, stepped on, or picked up. Bites can be very painful, but are seldom fatal. common adder 6 common adder The specific name, berus, is New Latin and was at one time used to refer to a snake, possibly the grass snake, Natrix natrix. common adder 7 common adder

The common adder is found in different terrains, habitat complexity being essential for different aspects of its behaviour. It feeds on small mammals, birds, lizards, and amphibians, and in some cases on spiders, worms, and insects. The common adder, like most other vipers, is ovoviviparous. Females breed once every two or three years, with litters usually being born in late summer to early autumn in the Northern Hemisphere. Litters range in size from three to 20 with young staying with their mothers for a few days. Adults grow to a total length (including tail) of 60 to 90 cm (24 to 35 in) and a mass of 50 to 180 g (1.8 to 6.3 oz). Three subspecies are recognized, including the nominate subspecies, Vipera berus berus described here. common adder 8 common adder The snake is not considered to be threatened, though it is protected in some countries.


Contents
1 Etymologies
2 Description
3 Geographic range
4 Conservation status
5 Habitat
6 Behaviour
7 Feeding
8 Reproduction
9 Venom
10 Taxonomy
11 See also
12 References
13 Further reading
14 External links
Etymologies
The name 'adder' is derived from nædre, an Old English word that had the generic meaning of serpent in the older forms of many Germanic languages. It was commonly used in the Old English version of the Christian Scriptures for the devil and the serpent in the Book of Genesis. common adder 5 common adder common adder 9 common adder In the 14th century, 'a nadder' in Middle English was rebracketed to 'an adder' (just as 'a napron' became 'an apron' and 'a nompere' changed into 'an umpire').

In keeping with its wide distribution and familiarity through the ages, Vipera berus has a large number of common names in English, which include:

Common European adder, common adder 3 common adder common European viper, common adder 4 common adder European viper, common adder 10 common adder northern viper, common adder 11 common adder adder, common adder, crossed viper, European adder, common adder 12 common adder common viper, European common viper, cross adder, common adder 13 common adder or common cross adder. common adder 14 common adder
In Denmark, Norway and Sweden, the snake is known as hugorm, hoggorm and huggorm, roughly translated as 'striking snake'. In Finland, it is known as kyykäärme or simply kyy, in Estonia it is known as rästik, while in Lithuania it is known as angis.

Description
Relatively thick-bodied, adults usually grow to 60 cm (24 in) in total length (including tail), with an average of 55 cm (22 in). common adder 3 common adder Maximum size varies by region. The largest, at over 90 cm (35 in), are found in Scandinavia; specimens of 104 cm (41 in) have been observed there on two occasions. In France and Great Britain, the maximum size is 80–87 cm (31–34 in). common adder 3 common adder Mass ranges from 50 g (1.8 oz) to about 180 grams (6.3 oz). common adder 15 common adder common adder 16 common adder

Shows the front parts of two common adders. One snake has the normal colour while the other has melanistic colour/pattern form. The head of the normal snake is enclosed in a half-coil of the melanistic form.
V. berus: normal and melanistic colour patterns
The head is fairly large and distinct and its sides are almost flat and vertical. The edge of the snout is usually raised into a low ridge. Seen from above, the rostral scale is not visible, or only just. Immediately behind the rostral, there are two (rarely one) small scales. Dorsally, there are usually five large plates: a squarish frontal (longer than wide, sometimes rectangular), two parietals (sometimes with a tiny scale between the frontal and the parietals), and two long and narrow supraoculars. The latter are large and distinct, each separated from the frontal by one to four small scales. The nostril is situated in a shallow depression within a large nasal scale. The eye is relatively large—equal in size or slightly larger than the nasal scale—but often smaller in females. Below the supraoculars are six to 13 (usually eight to 10) small circumorbital scales. The temporal scales are smooth (rarely weakly keeled). There are 10–12 sublabials and six to 10 (usually eight or 9) supralabials. Of the latter, the numbers 3 and 4 are the largest, while 4 and 5 (rarely 3 and 4) are separated from the eye by a single row of small scales (sometimes two rows in alpine specimens). common adder 3 common adder

Midbody there are 21 dorsal scales rows (rarely 19, 20, 22, or 23). These are strongly keeled scales, except for those bordering the ventral scales. These scales seem loosely attached to the skin and lower rows become increasingly wide; those closest to the ventral scales are twice as wide as the ones along the midline. The ventral scales number 132–150 in males and 132–158 in females. The anal plate is single. The subcaudals are paired, numbering 32–46 in males and 23–38 in females. common adder 3 common adder

The colour pattern varies, ranging from very light-coloured specimens with small, incomplete, dark dorsal crossbars to entirely brown ones with faint or clear, darker brown markings, and on to melanistic individuals that are entirely dark and lack any apparent dorsal pattern. However, most have some kind of zigzag dorsal pattern down the entire length of their bodies and tails. The head usually has a distinctive dark V or X on the back. A dark streak runs from the eye to the neck and continues as a longitudinal series of spots along the flanks. common adder 3 common adder Unusually for snakes, the sexes are possible to tell apart by the colour. Females are usually brownish in hue with dark-brown markings, the males are pure grey with black markings. The basal colour of males will often be slightly lighter than that of the females, making the black zigzag pattern stand out. The melanistic individuals are often females.

Geographic range
Vipera berus has a wide range. It can be found across the Eurasian land-mass; from northwestern Europe (Great Britain, Netherlands, Scandinavia, Germany, France) across southern Europe (Italy, Serbia, Albania, Croatia, Montenegro, Bosnia and Herzegovina, Republic of Macedonia, Bulgaria, and northern Greece) and eastern Europe to north of the Arctic Circle, and Russia to the Pacific Ocean, Sakhalin Island, North Korea, northern Mongolia and northern China. It is found further north than any other snake species. common adder citation needed common adder The type locality was originally listed as 'Europa'. Mertens and Müller (1940) proposed restricting the type locality to 'Upsala, Schweden' (Uppsala, Sweden) common adder 2 common adder and it was eventually restricted to Berthåga, Uppsala by designation of a neotype by Krecsák & Wahlgren (2008). common adder 17 common adder

In several European countries, it is notable as being the only native venomous snake. It is one of only four snake species native to Britain. The other three, the grass snake, barred grass snake and the smooth snake, are non-venomous. common adder 18 common adder

Conservation status
In the United Kingdom, it is illegal to kill, injure, harm or sell adders under the Wildlife and Countryside Act 1981. common adder 19 common adder The same situation applies to Norway under the Viltloven (The Wildlife Act 1981) common adder 20 common adder and Denmark (1981). common adder 21 common adder The common viper is categorised as 'endangered' in Switzerland, common adder 22 common adder and is also protected in some other countries in its range. It is also found in many protected areas. common adder 1 common adder This species is listed as protected (Appendix III) under the Berne Convention. common adder 23 common adder

The International Union for the Conservation of Nature Red List of Threatened Species describes the conservation status as of 'least concern' in view of its wide distribution, presumed large population, broad range of habitats, and likely slow rate of decline though it acknowledges the population to be decreasing. common adder 24 common adder Reduction in habitat for a variety of reasons, fragmentation of populations in Europe due to intense agriculture practices, and collection for the pet trade or for venom extraction have been recorded as major contributing factors for its decline. common adder 1 common adder

Habitat
A common adder basking in the open upon loose moss litter with head resting upon its coil and facing away. The central part of its body is thick and it has probaby eaten recently.
V. berus
Sufficient habitat complexity is a crucial requirement for the presence of this species, in order to support its various behaviours—basking, foraging, and hibernation—as well as to offer some protection from predators and human harassment. common adder 3 common adder It is found in a variety of habitats, including: chalky downs, rocky hillsides, moors, sandy heaths, meadows, rough commons, edges of woods, sunny glades and clearings, bushy slopes and hedgerows, dumps, coastal dunes, and stone quarries. It will venture into wetlands if dry ground is available nearby and thus may be found on the banks of streams, lakes, and ponds. common adder 25 common adder

An adult female adder found basking in the sun by Loch Shin, Sutherland in Scotland. She preferred to pose for a photograph rather than slither away.
V. berus female
In much of southern Europe, such as southern France and northern Italy, it is found in either low lying wetlands or at high altitudes. In the Swiss Alps, it may ascend to about 3,000 m (9,800 ft). In Hungary and Russia, it avoids open steppeland; a habitat in which V. ursinii is more likely to occur. In Russia, however, it does occur in the forest steppe zone. common adder 25 common adder

Behaviour
A slender adder lies in a half circle on the bare soil which has a few dried leaves. The black zig-zag pattern along the dorsal spine of the snake contrasts against the white borders forming a pattern resembling the teeth of an open zip.
V. berus male
This species is mainly diurnal, especially in the north of its range. Further south it is said common adder 26 common adder to be active in the evening, and it may even be active at night during the summer months. It is predominantly a terrestrial species, although it has been known to climb up banks and into low bushes in order to bask or search for prey. common adder 25 common adder

Adders are not usually aggressive, tending to be rather timid and biting only when cornered or alarmed. People are generally bitten only after stepping on them or attempting to pick them up. They will usually disappear into the undergrowth at a hint of any danger, but will return once all is quiet, often to the same spot. Occasionally, individual snakes will reveal their presence with a loud and sustained hissing, hoping to warn off potential aggressors. Often, these turn out to be pregnant females. When the adder is threatened, the front part of the body is drawn into an S-shape to prepare for a strike. common adder 25 common adder

The species is cold-adapted and hibernates in the winter. In Great Britain, males and females hibernate for about 150 and 180 days, respectively. In northern Sweden hibernation lasts 8–9 months. On mild winter days, they may emerge to bask where the snow has melted and will often travel across snow. About 15% of adults and 30–40% of juveniles die during hibernation. common adder 3 common adder

Feeding
Diet consists mainly of small mammals, such as mice, voles, and shrews, as well as lizards. Sometimes, slow worms are taken, and even weasels and moles. They feed on amphibians, such as frogs, newts, and salamanders. Birds are also reported common adder 27 common adder to be consumed, especially nestlings and even eggs, for which they will climb into shrubbery and bushes. Generally, diet varies depending on locality. common adder 25 common adder Juveniles will eat nestling mammals, small lizards and frogs as well as worms and spiders. Once they reach about 30 cm (0.98 ft) in length, their diet begins to resemble that of the adults. common adder 3 common adder

Reproduction
In Hungary, mating takes place in the last week of April, while in the north it happens later in the second week of May. Matings have also been observed in June and even early October, but it is not known if the autumn matings result in any young. common adder 3 common adder Females often breed once every two years, common adder 25 common adder or even once every three years if the seasons are short and the climate is severe. common adder 3 common adder

Closeup of snake coils with head resting on coil looking front and left. The gray dorsal scales on the thick coils are clearly seen as having prominent keels.
V. berus – showing strongly keeled scales on dorsal area.
Males find females by following their scent trails, sometimes tracking them for hundreds of meters a day. If a female is found and flees, the male follows. Courtship involves side-by-side parallel 'flowing' behaviour, tongue flicking along the back and excited lashing of the tail. Pairs stay together for one or two days after mating. Males chase away their rivals and engage in combat. Often, this also starts with the aforementioned flowing behaviour before culminating in the dramatic 'adder dance'. common adder 3 common adder In this act, the males confront each other, raise up the front part of the body vertically, make swaying movements and attempt to push each other to the ground. This is repeated until one of the two becomes exhausted and crawls off to find another mate. Appleby (1971) notes that he has never seen an intruder win one of these contests, as if the frustrated defender is so aroused by courtship that he refuses to lose his chance to mate. common adder 28 common adder There are no records of any biting taking place during these bouts. common adder 25 common adder

Females usually give birth in August or September, but sometimes as early as July, or as late as early October. Litters range in size from 3 to 20. The young are usually born encased in a transparent sac from which they must free themselves. Sometimes, they succeed in freeing themselves from this membrane while still inside the female. The neonates measure 14 to 23 cm (5.5 to 9.1 in) in total length (including tail), with an average total length of 17 cm (6.7 in). They are born with a fully functional venom apparatus and a reserve supply of yolk within their bodies. They shed their skins for the first time within a day or two. Females do not appear to take much interest in their offspring, but the young have been observed to remain near their mothers for several days after birth. common adder 25 common adder

Venom

Vipera berus - Venom delivery apparatus
Because of the rapid rate of human expansion throughout the range of this species, bites are relatively common. Domestic animals and livestock are frequent victims. In Great Britain, most instances occur in March–October. In Sweden, there are about 1,300 bites a year, with an estimated 12% that require hospitalisation. common adder 3 common adder At least eight different antivenoms are available against bites from this species. common adder 29 common adder

Mallow et al. (2003) describe the venom toxicity as being relatively low compared to other viper species. They cite Minton (1974) who reported the LD50 values for mice to be 0.55 mg/kg IV, 0.80 mg/kg IP and 6.45 mg/kg SC. As a comparison, in one test the minimum lethal dose of for a guinea pig was 40–67 mg, but only 1.7 mg was necessary when Daboia russelii venom was used. common adder 3 common adder Brown (1973) gives a higher subcutaneous LD50 range of 1.0–4.0 mg/kg. common adder 14 common adder All agree that the venom yield is low: Minton (1974) mentions 10–18 mg for specimens 48–62 cm (19–24.5 in) in length, common adder 3 common adder while Brown (1973) lists only 6 mg. common adder 14 common adder

Head of common adder strikes around the edge of a leather glove and manages to get the left fang piercing the leather causing a small stain
Vipera berus; the one erect fang has left a small venom stain on the glove.
Relatively speaking, bites from this species are not highly dangerous. common adder 3 common adder In Britain there have been only 14 known fatalities since 1876—the last a 5-year-old child in 1975 common adder 6 common adder —and one nearly fatal bite of a 39-year-old woman in Essex in 1998. common adder 6 common adder An 82-year-old woman died following a bite in Germany in 2004, although it is not clear whether her death was due to the effect of the venom. common adder 30 common adder Even so, professional medical help should always be sought as soon as possible after any bite. Very occasionally bites can be life-threatening, particularly in small children, while adults may experience discomfort and disability long after the bite. common adder 6 common adder The length of recovery varies, but may take up to a year. common adder 3 common adder

Local symptoms include immediate and intense pain, followed after a few minutes (but perhaps by as much as 30 minutes) by swelling and a tingling sensation. Blisters containing blood are not common. The pain may spread within a few hours, along with tenderness and inflammation. Reddish lymphangitic lines and bruising may appear, and the whole limb can become swollen and bruised within 24 hours. Swelling may also spread to the trunk, and with children, throughout the entire body. Necrosis and intracompartmental syndromes are very rare. common adder 6 common adder

Systemic symptoms resulting from anaphylaxis can be dramatic. These may appear within 5 minutes post bite, or can be delayed for many hours. Such symptoms include nausea, retching and vomiting, abdominal colic and diarrhoea, incontinence of urine and faeces, sweating, fever, vasoconstriction, tachycardia, lightheadedness, loss of consciousness, blindness, common adder 31 common adder shock, angioedema of the face, lips, gums, tongue, throat and epiglottis, urticaria and bronchospasm. If left untreated, these symptoms may persist or fluctuate for up to 48 hours. common adder 6 common adder In severe cases, cardiovascular failure may occur. common adder 3 common adder

Taxonomy
The species has three recognised subspecies :

Subspecies common adder 8 common adder Taxon author common adder 8 common adder Common name Geographic range
V. b. berus (Linnaeus, 1758) Common European adder common adder 3 common adder Norway, Sweden, Finland, Latvia, Estonia, Lithuania, France, Denmark, Germany, Austria, Switzerland, Northern Italy, Belgium, Netherlands, Great Britain, Poland, Czech Republic, Slovakia, Slovenia, Hungary, Romania, Russia, Mongolia, Northwest China (north Xinjiang)
V. b. bosniensis Boettger, 1889 Balkan cross adder common adder 13 common adder Balkan Peninsula
V. b. sachalinensis Zarevskij, 1917 Sakhalin Island adder common adder 12 common adder Russian Far East (Amur Oblast, Primorskye Kray, Khabarovsk Kray, Sakhalin Island), North Korea, Northeast China (Jilin)
The subspecies V. b. bosniensis and V. b. sachalinensis have been regarded as full species in some recent publications. common adder 3 common adder