Adder

Adder, common name for snakes in several families. One of the best-known adders is the common adder, or common European viper. Like all vipers, the common adder is venomous, but it is less aggressive than most venomous snakes and its bite is rarely fatal to humans. This reptile is the only venomous snake found in Great Britain and the only snake in Scotland. Its wide range extends from Spain through much of northern Eurasia east to the Pacific Ocean and north to the Arctic Circle, the farthest north of any venomous snake. Adders live in a variety of habitats, including moors, bogs, open woods, moist meadows, and hedgerows. The common adder occurs in lowlands and in mountainous regions up to about 3000 m (about 10,000 ft) in the Alps.

The common adder grows to lengths of 65 cm (25.5 in) and occasionally reaches 90 cm (35 in). Adult males are usually pale gray with a contrasting black pattern of dorsal zigzag stripes; adult females may be brown or reddish-brown with a dark brown pattern of zigzag stripes. Individuals from some populations may be entirely black. The common adder is mostly diurnal and preys heavily on small rodents, but it also eats lizards. It gives birth to live young. In the southern portion of the range, females may reproduce every year; in the north, females give birth only every two or three years.

Other vipers in the same genus as the common adder are sometimes referred to as adders, including, at one extreme, the Orsini viper of Europe, which lives largely on insects and appears to use its venom rarely, even when handled; and, at the other extreme, the daboia, or Russell's viper, of southeastern Asia, which has probably caused more human fatalities than any other species of viper.

In Africa many snakes of the viper family are sometimes also called adders, including the berg adder; the dwarf adder; the Gaboon adder; the horned adder; the many-horned adder; the mountain, or African Cape, adder; the puff adder; and the night adders.

Because of their appearance or behavior, other snakes unrelated to vipers are also called adders. The three species of Australian death adders are actually members of the cobra family. In the United States several harmless snakes are called adders. For example, hognose snakes are sometimes called spreading adders or hissing adders; although they rarely bite, they puff up and hiss wildly when disturbed.

See Viper.

Scientific classification: Most adders belong to the family Viperidae. The common adder is classified as Vipera berus, the Orsini viper as Vipera ursinii macrops, and the daboia, or Russell's viper, as Vipera russelli. The berg, dwarf, Gaboon, horned, many-horned, mountain or African Cape, and puff adders all belong to the genus Bitis. The night adders, of which there are several species, are classified in the genus Causus. The death adders belong to the family Elapidae; the widest ranging of the three species is classified as Acanthophis antarcticus. Hognose snakes make up the genus Heterodon of the family Colubridae.