Common European Adder

## Description

The Common European adder (Vipera berus) is a venomous snake that is very widespread and can be found throughout most of central and eastern Europe and as far as 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; they are not aggressive and usually bite only when really provoked, stepped on, or picked up. Bites can be very painful but are seldom fatal.

## Appearance

The color pattern of these snakes 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 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. Unusually for snakes, the sexes are possible to tell apart by the color. Females are usually brownish in hue with dark-brown markings, the males are pure grey with black markings. The basal color of males will often be slightly lighter than that of females, making the black zigzag pattern stand out. Melanistic individuals are often females.

## Distribution

Common European adders have a wide range. They can be found across the Eurasian land-mass; from northwestern Europe (Great Britain, Belgium, Netherlands, Scandinavia, Germany, France) across southern Europe (Italy, Serbia, Albania, Croatia, Montenegro, Bosnia and Herzegovina, North Macedonia, Bulgaria, and northern Greece) and eastern Europe to the north of the Arctic Circle, and Russia to the Pacific Ocean, Sakhalin Island, North Korea, northern Mongolia, and northern China. They are found further north than any other snake species. European adders live 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. They will venture into wetlands if the dry ground is available nearby and thus may be found on the banks of streams, lakes, and ponds.

## Behavior

Common European adders are mainly diurnal, especially in the north of their range. Further south they are known to be active in the evening, and may even be active at night during the summer months. Adders are predominantly terrestrial, although they may climb up banks and into low bushes in order to bask or search for prey. They are generally solitary and may be seen together only during hibernation and breeding season. These snakes hibernate communally in the winter. On mild winter days, they may emerge to bask where the snow has melted and will often travel across snow. Adders are not usually aggressive; they are rather timid and bite 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.

## Venom

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. At least eight different antivenoms are available against bites from this species. 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. Surprisingly, Norway has on average registered one death from the snake every 10 years, despite only having 200-500 reports of bites 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 diarrhea, sweating, fever, vasoconstriction, tachycardia, lightheadedness, loss of consciousness, blindness, 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. In severe cases, cardiovascular failure may occur.

## Diet

Common European adders are carnivores. Their diet consists mainly of small mammals, such as mice, rats, 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 consumed, especially nestlings and even eggs, for which they will climb into shrubbery and bushes. Juveniles will eat nestling mammals, small lizards, and frogs as well as worms and spiders.

## Reproduction

Common European adders are polygynous meaning that males mate with multiple females during the breeding season. Pairs stay together for one or two days after mating. Adders usually mate in spring and females often breed once every two years. Males find females by following their scent trails, sometimes tracking them for hundreds of meters a day. If a female is found and then flees, the male follows. Courtship involves side-by-side parallel 'flowing' behavior, tongue flicking along the back, and excited lashing of the tail. 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. Females give birth to 3-20 live young usually in August or September, but sometimes as early as July, or as late as early October. The gestation period lasts 3 to 4 months. The young are usually born encased in a transparent sac from which they must free themselves. The neonates measure 14-23 cm (5.5-9.1 in) in total length (including the tail). 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. Young adders become reproductively mature at 3 to 4 years of age.

## Population

### Population threats

The Common European adder is not considered to be threatened, though it is protected in some countries. 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 to its decline.

### Population number

According to IUCN, the Common European adder is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.

### Ecological niche

These snakes play an important role in their ecosystem. They control the populations of species they prey on, particularly rodents, small birds, frogs, and lizards. Adders are also prey for larger mammals and birds.

## Fun Facts

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.

In Denmark, Norway, and Sweden, this 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. In Poland, the snake is called żmija zygzakowata, which translates as 'zigzag viper', due to the pattern on its back.

Adders have been the subject of much folklore in Britain and other European countries. They are not regarded as especially dangerous; these snakes are not aggressive and usually bite only when really provoked, stepped on, or picked up.

## Gallery

https://animalia.bio/common-european-adder