Europe's adder ranges farther north than any snake
Vipera berus, the common European adder, stretches from Britain to Sakhalin and crosses the Arctic Circle—farther north than any other snake. Folklore paints it as a devilish villain, yet it usually bites only when stepped on or handled. Painful yes; rarely fatal. Britain has just three native snakes, and this is the only venomous one.
Three subspecies are usually recognised, though some authors elevate the Balkan and Sakhalin forms. Adults typically reach about sixty centimetres, averaging near fifty-five, with Scandinavian giants past ninety centimetres and two recorded at one hundred four. Mass runs from about fifty to one hundred eighty grams. Most wear a zigzag dorsal stripe and a dark V or X on the head; males often look grey with black marks, females browner, and some females are fully melanistic. The English word adder began as Old English nædre for snake, then rebracketed from a nadder to an adder in Middle English—the same linguistic slide that gave us apron and umpire.
Habitat must be complex enough for basking, hunting, and winter dens: heaths, woodland edges, dunes, quarries, alpine meadows. In the Swiss Alps it may climb to about three thousand metres. Diet centres on small mammals, lizards, and amphibians, with nestling birds and occasional invertebrates. Like most vipers it is ovoviviparous; females breed every two or three years and produce litters of three to twenty in late summer or early autumn. Hibernation is long—about one hundred fifty days for British males and one hundred eighty for females, stretching to eight or nine months in northern Sweden—and roughly fifteen percent of adults and thirty to forty percent of juveniles die over winter.
Protection varies. Britain bans killing or selling adders under the Wildlife and Countryside Act 1981; similar rules apply in Norway, Denmark, Finland, and Sweden, with limited last-resort exceptions on private land. The Berne Convention lists the species on Appendix III. Globally the IUCN rates it least concern thanks to a huge range, yet notes a declining population driven by habitat loss, agricultural fragmentation, and collecting. A UK citizen-science survey reported extensive local declines. Timid by habit, an adder usually vanishes into cover; a loud hiss is more warning than bluff.
Source: Adder
