The Common Adder (Vipera berus), commonly known as the European adder or common viper, is a venomous snake from the Viperidae family, widespread across Europe and parts of East Asia. It is not considered highly dangerous, typically biting only when provoked; while bites can be painful, they are rarely fatal.
Adders inhabit various terrains and feed on small mammals, birds, lizards, and amphibians. They are ovoviviparous, with females usually giving birth every two to three years to litters of three to 20 young. Adults typically measure 60 to 90 cm in length and weigh between 50 and 180 g.
Physically, they have a distinct head and a pattern of dorsal scales. Their coloration varies significantly, with light-colored specimens displaying dark crossbars and melanistic individuals appearing entirely dark. Generally, females are brown with darker markings, while males are gray with black patterns.
Vipera berus, commonly known as the adder, has a wide range across Eurasia, found in northwestern and southern Europe, eastern Europe, and extending to northern Asia and parts of China. It is notable for being the only native venomous snake in several European countries and one of only three snake species in Britain, alongside the non-venomous barred grass snake and smooth snake.
The species requires diverse habitats for activities like basking and foraging, thriving in environments such as chalky downs, rocky hills, and woodland edges. In southern Europe, it typically resides in wetlands or high altitudes, while avoiding open steppeland in places like Hungary and Russia.
Adder behavior is primarily diurnal in northern ranges but can be active in the evening or at night in southern areas. They are generally timid and only bite when threatened. When alarmed, they may hiss to warn off threats, particularly pregnant females. As a cold-adapted species, adders hibernate for varying durations depending on the region, with a significant mortality rate during this period.
Adders primarily feed on small mammals like mice, rats, and voles, as well as lizards and amphibians such as frogs and newts. Juveniles consume nestling mammals, small lizards, and worms, with the alpine salamander being a significant dietary source. Males locate females by following scent trails and engage in courtship through synchronized movements and displays. During mating season, males may fight in a behavior known as the “adder dance,” where they attempt to push each other down without biting.
Females usually give birth from July to October, with litters ranging from 3 to 20 neonates that are 14 to 23 cm long. They are born with functional venom and typically shed their skins shortly after birth. Mothers show minimal interest in their offspring, but the young may stay close for a few days post-birth.
