Vipera berus

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Vipera berus is a venomous viper species known as the common European adder. This species is extremely widespread and can be found throughout Europe, Great Britain and all the way to Far East Asia. As opposed to most other viperids, it prefers lower average temperatures, occurring at either higher latitudes (to within the Arctic circle) or higher altitudes (reaching 3000 m in the Swiss Alps). Other common names for it are northern viper and crossed viper. Besides the typical form, two other subspecies are recognized.

Contents

1 Description
2 Food
3 Habitat
4 Behavior
5 Reproduction
6 Subspecies
7 Taxonomy
8 Venom
9 Notes
10 References
11 Further reading
12 External links
13 See also

Description

V. berus is a small snake: adult females rarely grow beyond 70 centimetres and males rarely over 60, although most specimens encountered are much smaller. They can reach 20-25 years of age.

Adult females are often a rusty brown ground colour with a black dorsal pattern, while males usually grey. Young individuals are sometimes dark brown and their correct colouring emerges only after a few years. Apart from their gender-specific colouring, there are also individuals that are very dark or almost black. This is caused by a pigment error, melanism, that is apparently not inherited by their young. Black vipers usually give birth to normal coloured young, and normal coloured vipers may give birth to black vipers. While their camouflage is not as good as the normal coloured snakes, the black crossed vipers have an advantage by being able to raise their body temperature more rapidly, which is especially useful after hibernation or in cold climates. Melanism appears to be more common in the northern regions than elsewhere throughout its range. The common name, crossed viper, comes from the black crossed pattern on its back.

Two colour variations of Vipera berus in Copenhagen Zoo.

Food

Their food consists mainly of rodents, amphibians and lizards, although birds and their eggs are sometimes consumed.

Habitat

V. berus is found farther north than any other snake and is known for being remarkably resistant to low temperatures. It is also the most widespread species of snake in the world and is found on Great Britain in the west, to the Chinese coast and Sakhalin in the east, and well within the Arctic Circle in the north. It is very adaptive and can be found in nearly any type of terrain and in mountains up to 3000 meters above sea level.

Behavior

V. berus is not an aggressive species and when approached by a human, it tends to rely on its camouflage for as long as possible, before trying to escape. Only when it is surprised or provoked will it try to bite. This is possibly due to the high amount of energy it needs to produce its venom and, because it lives mostly in a temperate climate, its need to conserve energy. Its reliance on camouflage has caused it to become an easy victim for humans, and it is now a protected species in most of Europe.

Reproduction

Their mating season is in May and the females give birth in August or September, depending on the climate. The crossed viper usually gives birth to 5-20 live young, depending on the size of the female. The snake is exceptional since it is known to both give birth and lay eggs, which usually hatch within minutes of being laid. When they are born, they are between 15-20 cm long and already venomous.

A common belief is that young and especially newborn vipers are more venomous than adult snakes, but this is untrue. Another belief is that they are so aggressive after they are born, that the female has to give birth hanging from a bush to avoid being bitten by its own offspring. This is also untrue, although vipers are known to give birth hanging in bushes, possibly since it aids them in pushing out the babies. After being born, the snakes usually shed their skins. Before they go into their first hibernation in October or November, the young snakes do not always feed, since they need to fully digest the meal before entering the hibernation state, to avoid complications resulting from the changes in its metabolism.

Subspecies

Subspecies	Authority	Geographic range
V. b. berus	Linnaeus, 1758	Norway, Sweden, Finland, France, Denmark, Germany, Austria, Switzerland, Northern Italy, Belgium, Netherlands, Great Britain, Poland, Czech Republic, Slovakia, Hungary, Romania, Russia, Mongolia, north-west China (north Xinjiang)
V. b. bosniensis	Boettger, 1889	Balkan Peninsula
V. b. sachalinensis	Zarevskij, 1917	Russian Far East (Amur Oblast, Primorskye Kray, Khabarovsk Kray, Sakhalin Island), North Korea, north-east China (Jilin)

Taxonomy

The subspecies bosniensis and sachalinensis are regarded as full species in some publications.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.Ananjeva NB, Borkin LJ, Darevsky IS, Orlov NL. 1998. Amphibiand and Reptiles. Encyclopedia of Nature of Russia. ABF Moscow (in Russian). 574 pp..

Venom

V. berus is venomous and the lethality of its venom is equal to that of rattlesnakes', but because it injects much smaller amounts of the venom, the animal is considered less dangerous. A bite from V. berus is only rarely lethal and even then it is usually due to an anaphylactic reaction. In fact, bees are considered more dangerous to humans and only small children, allergic adults and seniors in poor health are at risk. Nevertheless, if bitten by V. berus, one should immediately but calmly seek medical assistance.

Notes

References

McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World. Herpetologists' League. ISBN 1893777006.
Mallow D, D Ludwig, G Nilson. 2003. True Vipers. Krieger Publishing Company. ISBN 0894648772.

External links

Amphibians and Reptiles of Europe - [Vipera berus]
Integrated Taxonomic Information System - [Vipera berus]
EMBL Reptile Database - [Family Viperidae]
Species [Vipera berus] at the [EMBL Reptile Database]