|Species:||V. berus berus|
Vipera berus, the common European adder or common European viper, is a venomous viper species that is extremely widespread and can be found throughout most of Western Europe and all the way to Far East Asia. 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. They are not regarded as especially dangerous; the snake is not aggressive and usually bites only when alarmed or disturbed. Bites can be very painful, but are seldom fatal. The specific name, berus, is New Latin and was at one time used to refer to a snake, possibly the grass snake, Natrix natrix.
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, amphibians and in some cases on spiders, worms and insects. Females breed once every two or three years with litters usually born in late summer to early autumn in the Northern hemisphere. The common adder, like most other vipers, is ovoviviparous; litters range in size from 3 to 20 with young staying with their mothers for a few days. Adults grow to a length of 60 to 90 centimetres (24 to 35 in) and a mass of 50 grams (1.8 oz) to about 180 grams (6.3 oz). Three subspecies are recognized, including the nominate subspecies, Vipera berus berus. described here. The snake is not considered to be threatened though it is protected in some countries.
Relatively thick-bodied, adults grow to 60 centimetres (24 in) in length with an average of 55 centimetres (22 in). Maximum size varies per region. The largest, at over 90 centimetres (35 in), are found in Scandinavia; specimens of 104 centimetres (41 in) have been observed there on two occasions. In France and Great Britain, the maximum size is 80–87 centimetres (31–34 in). Mass ranges from 50 grams (1.8 oz) to about 180 grams (6.3 oz).
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 2 (rarely 1) small scales. Dorsally, there are usually 5 large plates: a squarish frontal (longer than wide, sometimes rectangular), 2 parietals (sometimes with a tiny scale between the frontal and the parietals), and 2 long and narrow supraoculars. The latter are large and distinct, each separated from the frontal by 1–4 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 there are 6–13 (usually 8–10) small circumorbital scales. The temporal scales are smooth (rarely weakly keeled). There are 10–12 sublabials and 6–10 (usually 8–9) 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).
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.
The color pattern varies, ranging from very light-colored 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 the body and tail. 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. Unusual 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.
Common names 
In keeping with its wide distribution and familiarity through the ages, Vipera berus has a large number of common names, which include:
- Common European adder, common European viper, European viper, northern viper, adder, common adder, crossed viper, European adder, common viper, European common viper, cross adder, or common cross adder.
In Sweden, Norway, and Denmark, it is known as "huggorm" or "hoggorm". In Finland, it is known as "kyykäärme" or simply "kyy" while in Estonia it is known as "rästik." The word "adder" was nædre in Old English; in the 14th century a nadder was, like a napron, rebracketed as an adder. It appears with the generic meaning of serpent in the older forms of many Germanic languages, and is thus used in the Old English version of the Christian Scriptures for the devil, the serpent of the Book of Genesis.
Geographic range 
Vipera berus has a wide range. It can be found across the Eurasian land-mass; from northwestern Europe (Great Britain, Scandinavia, Germany, France) across southern Europe (Italy, Serbia, Albania, Croatia, 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. The type locality was originally listed as "Europa". Mertens and Müller (1940) proposed restricting the type locality to "Upsala, Schweden" (Uppsala, Sweden) and it was eventually restricted to Berthåga, Uppsala by designation of a neotype by Krecsák & Wahlgren (2008).
In several European countries it is notable as being the only native venomous snake.
Conservation status 
In the United Kingdom, it is illegal to kill, injure, harm, or sell adders under the 1981 Wildlife and Countryside Act. The common viper is categorised as "endangered" in Switzerland, and is also protected in some other countries in its range. It is also found in many protected areas. This species is listed as protected (Appendix III) under the Berne Convention.
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. 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.
Sufficient habitat complexity is a crucial requirement for the presence of this species, in order to support their various behaviors—basking, foraging, and hibernation—as well as to offer some protection from predators and human harassment. It is found in 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. They will venture into wetlands if dry ground is available nearby and thus may be found on the banks of streams, lakes, and ponds.
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 (9,842 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.
This species is mainly diurnal, especially in the north of its range. Further south it is said 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.
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.
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.
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 to be on the menu, especially nestlings and even eggs, for which they will climb into shrubbery and bushes. Generally, diet varies depending on locality. Juveniles will eat nestling mammals, small lizards and frogs as well as worms and spiders. Once they reach about 30 cm (1 ft) in length, their diet begins to resemble that of the adults.
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. Females often breed once every two years, or even once every three years if the seasons are short and the climate is severe.
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" behavior, 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 behavior before culminating in the dramatic "adder dance." 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. Interestingly, 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. There are no records of any biting taking place during these bouts.
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, measuring 14 to 23 cm (average of 17 cm; 7 in), 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.
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. At least eight different antivenoms are available against bites from this species.
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. Brown (1973) gives a higher subcutaneous LD50 range of 1.0–4.0 mg/kg. All agree that the venom yield is low: Minton (1974) mentions 10–18 mg for specimens 48–62 cm (19–24 in) in length, while Brown (1973) lists only 6 mg.
Relatively speaking, bites from this species are not highly dangerous. In Britain there have been only 14 known fatalities since 1876; the last a 5-year-old child in 1975. and one near fatal bite of a 39 year old woman in Essex in 1998. 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. 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. The length of recovery varies, but may take up to a year.
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.
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, shock, angioedema of the face, lips, gums, tongue, throat and epiglotis, urticaria and bronchospam. If left untreated, these symptoms may persist or fluctuate for up to 48 hours. In severe cases, cardiovascular failure may occur.
The species has three recognised subspecies :
|Subspecies||Taxon author||Common name||Geographic range|
|V. b. berus||(Linnaeus, 1758)||Common European adder||Norway, Sweden, Finland, Latvia, Estonia, Lithuania, France, Denmark, Germany, Austria, Switzerland, Northern Italy, Belgium, Netherlands, Great Britain, Poland, Czech Republic, Slovakia, Hungary, Romania, Russia, Mongolia, Northwest China (north Xinjiang)|
|V. b. bosniensis||Boettger, 1889||Balkan cross adder||Balkan Peninsula|
|V. b. sachalinensis||Zarevskij, 1917||Sakhalin Island adder||Russian Far East (Amur Oblast, Primorskye Kray, Khabarovsk Kray, Sakhalin Island), North Korea, north-east China (Jilin)|
The subspecies V. b. bosniensis and V. b. sachalinensis have been regarded as full species in some recent publications.
See also 
- List of viperine species and subspecies
- Viperinae by common name
- Viperinae by taxonomic synonyms
- List of reptiles of Italy
- Isailovic, Jelka Crnobrnja et al. (2009). Vipera berus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.
- McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Krieger Publishing Company, Malabar, Florida. ISBN 0-89464-877-2.
- Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. ISBN 0-448-11856-4.
- ""Everyday adders" – the Adder in Folklore". The Herpetological Conservation Trust. Retrieved 7 February 2010.
- Warrell DA (2005). "Treatment of bites by adders and exotic venomous snakes". British Medical Journal 331 (7527): 1244–7. doi:10.1136/bmj.331.7527.1244. PMC 1289323. PMID 16308385.
- Gotch AF. 1986. Reptiles – Their Latin Names Explained. Poole, UK: Blandford Press. ISBN 0-7137-1704-1.
- "Vipera berus". Integrated Taxonomic Information System. Retrieved 15 August 2006.
- Olsson, M.; Madsen, T.; Shine, R. (1997). "Is sperm really so cheap? Costs of reproduction in male adders,Vipera berus". Proceedings of the Royal Society B: Biological Sciences 264 (1380): 455–459. doi:10.1098/rspb.1997.0065. JSTOR 50437. PMC 1688262. (includes chart showing range of male mass in one population)
- Strugariu, Alexandru; Zamfirescu, Ştefan R. and Gherghel, Iulian (2009). "First record of the adder (Vipera berus berus) in Argeş County (Southern Romania)". Biharean Biologist 3 (2): 164. (gives example masses of females)
- U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. ISBN 0-486-26629-X.
- Vipera berus at the Reptarium.cz Reptile Database. Accessed 21 November 2007.
- Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. ISBN 0-8069-6460-X.
- Steward JW. 1971. The Snakes of Europe. Cranbury, New Jersey: Associated University Press (Fairleigh Dickinson University Press). LCCCN 77-163307. ISBN 0-8386-1023-4.
- Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. LCCCN 73-229. ISBN 0-398-02808-7.
- "adder". Dictionary.com Unabridged. Random House, Inc. Retrieved 7 February 2010.
- Krecsák L. and Wahlgren R. (2008). "A survey of the Linnaean type material of Coluber berus, Coluber chersea and Coluber prester (Serpentes, Viperidae)". Journal of Natural History 42 (35–36): 2343. doi:10.1080/00222930802126888.
- "Adder (Vipera berus)". Arkive (Images of life on Earth). www.wildscreen.org.uk. Retrieved 7 February 2010.. This ref cites Beebee, T. & Griffiths, R. (2000) Amphibians and reptiles: a natural history of the British herpetofauna. Harper Collins Publishers Ltd, London. as the source.
- Monney JC, Meyer A. 2005. Rote Liste der gefährdeten Reptilien der Schweiz. Hrsg. Bundesamt für Umwelt, Wald und Landschaft BUWAL, Bern und Koordinationsstelle für Amphibien- und Reptilienschutz der Schweiz, Bern. BUWAL-Reihe.
- Convention on the Conservation of European Wildlife and Natural Habitats, Appendix III at Council of Europe. Accessed 7 February 2010.
- "IV: The Categories". 2001 IUCN Red List Categories and Criteria version 3.1. www.iucnredlist.org. Retrieved 14 February 2010.
- Street D. 1979. The Reptiles of Northern and Central Europe. London: B.T. Batsford Ltd. ISBN 0-7134-1374-3.
- Boulenger, G.A.. (1913).Snakes of Europe. Methuen & Co, London
- Leighton, Gerald R. (1901). The Life-History of British Serpents and Their Local Distribution in the British Isles. Edinburgh & London: Blackwood & sons. p. 84. ISBN 1-4446-3091-1. Retrieved 8 February 2010.
- Appleby, L. G. (1971). British Snakes. London (Baker), ISBN 0-212-98393-8.
- Vipera berus antivenoms at Munich Antivenom Index. Accessed 15 September 2006.
- Tod durch Kreuzotterbiss? at Gemeinsames Giftinformationszentrum. Accessed 25 May 2007.
- Macrae, Fiona (21 July 2010) Adder bite leaves father blinded, choking and just minutes from death on walk with family. The Daily Mail, retrieved on 21 July 2010.
Further reading 
- Ananjeva NB, Borkin LJ, Darevsky IS, Orlov NL. 1998. Amphibians and Reptiles. Encyclopedia of Nature of Russia. ABF Moscow (in Russian).
- Appleby L.G. 1971. British Snakes. London: J. Baker. ISBN 0-212-98393-8.
- Joger U, Lenk P, Baran I, Böme W, Ziegler T, Heidrich P, Wink M. 1997. The phylogenetic position of Vipera barani and of Vipera nikolskii within the Vipera berus complex.
- Minton S.A. Jr. 1974. Venom Diseases. Springfield (IL): CC Thomas Publ.
- Wüster W, Allum CSE, Bjargardottir IB, Bailey KL, Dawson KJ, Guenioui J, Lewis J, McGurk J, Moore AG, Niskanen M, Pollard CP. 2004. Do aposematism and Batesian mimicry require bright colours? A test, using European viper markings. Proceedings of the Royal Society of London. B 271 pp 2495–2499. PDF at Wolfgang Wüster, School of Biological Sciences, University of Wales, Bangor. Accessed on 15 August 2006.
|Wikimedia Commons has media related to: Vipera berus|
|Wikispecies has information related to: Vipera berus|
|Wikisource has the text of the 1921 Collier's Encyclopedia article Adder.|
- Vipera berus at Surrey Amphibian and Reptile Group (SARG)
- Vipera berus European Field Herping Community
- Vipera berus at Amphibians and Reptiles of Europe. Accessed on 16 August 2006.
- Vipera berus media at ARKive
- Adder or Viper – Vipera berus at Reptiles and Amphibians of the UK. Accessed 9 October 2006.
- Vipera berus at Club100. Accessed 9 October 2006.
- Viper berus – Adder at First Nature. Accessed 9 October 2006.
- Adder (Vipera berus) at Warwickshire Amphibian and Reptile Team. Accessed 11 February 2010 .
- Adder, Vipera berus at Reptiles & Amphibians of France. Accessed 6 June 2008.
- Vipera berus images at Hribi.net. Accessed 7 February 2010.
- Snakes at Froglife, UK (now part of Amphibian & reptile conservation Trust). Dead site archived by www.archive.org. Accessed 11 February 2010.
- Add an Adder (UK Herpetological Conservation Trust). Accessed 31 December 2007.
- James Stroud Research and Contact Details (University of Hull, UK)