Adder, Vipera berus
(Linnaeus, 1758)

History and origin
The Adder, or Common viper was first described by Linnaeus in 1758, the scientific name of this species is Vipera berus, Vipera meaning viper and berus meaning 'true', 'common' as it is really the original viper.

Characteristics
They are distinguished from other widespread viper species by their relatively small and blunt head.

Description
=Size=
They are born at around 15 cm, growing up to sometimes 75 cm.
=Morphology=
They are short and relatively elegant, sometimes stout looking (especially females). Their head is less heavily built then that of most other vipers. Like other vipers, they have keeled scales and vertical pupils.
=Patterns & colours=
This species is quite stable in pattern, but less in colour, depending on the geographical area. A typical male is whitish, creamy or light gray with a dark dorsal zigzag pattern and sometimes spots or irregular darker patterns on the flanks. A typical female is more brownisg, reddish, rusty or orange in colour with the same dorsal and flank patterns. Black specimens occur. These black specimens often have deep red eyes, whereas normal specimens tend to have a lighter eye, sometimes yellowish or orange, but rarely red.

Geographical range
Very widespread. Can be found as far north as Finland and Norway. They are present over Great Britain, in the northern third of France and in the Massif Central region, in Belgium, the Netherlands, across most of Germany, Switzerland, northern Italy, Austria, and most of eastern Europe, yet the Balkans this species is missing from most of Greece, western Albania, much of Croatia, east of Bulgaria, much of Romania and much of Hungary.

Subspecies
- berus - Found over entire described territory, expect the Balkans. Typical animals are described above.
- bosniensis - Found in the Balkans. They can look much like Vipera aspis. Their pattern is often broken up into blotches and unlinked cross-bands. Regarde by some as a separate species.

Sexual differences
Females are larger then the males, especially in late spring when they carry their young.

Seasonal variations
None.

Diet
They mainly eat small mammals but also lizards and other reptiles and birds. Juveniles often feed on lizards (often Viviparous Lizard (Zootoca vivipara)). Adults eat about 5 to 6 mice a year.

Defensive habits
They prefer to escape but if cornered or caught they will hiss very loudly and for long periods, and rapidly striking with their mouth open. The temperament depends on individual specimens... When they bite, they usually don’t they often don't inject any venom and they give what is known as a ‘dry bite’ they also can choose to use their fangs or not by retracting them (as can do all viperidae species), we must remember that this snake as like other venomous snakes have not got the capability to envenomate us to harm us but to kill their prey in order to survive.

Reproduction
Breeding occurs when the snakes wake up from hibernation in spring, a week after, they are all looking for each other and mating begins. The female carries around with her about 15 young (extremes of 5 to 18). They are born 2 to 3 months after being conceived. In northern parts of its range where a cool summer may occur, the young are born the following year.

Sexual maturity, life span
The average life span for Vipera berus is about 12 years, they reach their sexual maturity in their third year for males and in the fifth for females.

Habits
Mainly diurnal, but may be nocturnal in hot weather. When they are disturbed, they may stay quite calm and move away quite slowly. They are slow and docile, until trapped or cornered, when they become very defensive biting rapidly. Most easily seen in rather warm but clouded conditions, basking to gain body heat. Optimal body temperature between 24 and 28 C. Air humidity seems an important factor in observing Adders: when the air is too dry, they don't expose themselves to sunshine, but stay in the vegetation. Hibernation goes from mid October until mid March, in dry places underground. Mouse and rabbit holes are often used for hibernation. Also holes under trees are used for this purpose. As soon as soil temperature rises above 10 C, they come out and expose themselves to sunshine. Males come out approximately 2 weeks earlier than females, often basking communally.

Venom
The Adder is the most widespread snake of Europe, but serious accidents seldom occur. Its venom can be powerful enough to kill a child or dog. Adult people will normally not die from a bite, however fatalities have been reported. They are front-fanged like all vipers. Adders are known to be able to control the amount of venom injected during a bite, thus avoiding waste of venom by unnecessary overdoses.

Habitat
In the lowlands, Vipera berus is found mostly in heaths and moors and other more or less humid areas. Sometimes, they are found in open bushy areas, adjacent to a heath. In the mountains of Europe, Vipera berus is found in open woodland, grasslands and damp meadows, mostly in relatively cool and not too dry places. As Adders prefer basking in sunshine at low temperatures, they avoid excessive heat or drought.

Predators
Apart from birds of prey and mammals, and the snakes of the genus Coronella (austriaca & girondica), the Adder doesn’t have too many predators, their worst enemy is humans.

Adder - © Bert Blok
Adder, Vipera berus - © Bert Blok

Adder - © Steve Langham
Adder, Vipera berus - © Steve Langham

Adder - © Konrad MebertAdder, Vipera berus - © Konrad Mebert

Adder - © Bert Blok
Adder, Vipera berus - © Bert Blok

Adder - © Bert Blok
Adder, Vipera berus - © Bert Blok

Adder - © Bert Blok
Adder, Vipera berus - © Bert Blok

Adder - © Konrad Mebert
Adder, Vipera berus - © Konrad Mebert