Adder – viperus berus


Britains most widespread reptile is also our only venomous one. It is found throughout mainland Britain, including some offshore islands, in a variety of open and man-made habitats. Although they have suffered somewhat from the reduction of moorland habitat in Britain, they remain relatively widespread.

Like most snakes, the adder can survive a fairly long time without eating, particularly in cooler weather and when hibernating over winter. It creeps up slowly on its prey and then strikes, biting and quickly releasing its prey. Its victim will succumb to the venom in up to three minutes and be swallowed whole. Their main prey are frogs, newts, lizards, small mammals and birds eggs.

Despite their venomous bite, adders will always attempt to flee from danger rather than confront it and its bite is rarely fatal for humans. Their main natural predators include buzzards and herons.


Size:Length up to 60 cm; male smaller than female. Young are about 14 cm when born.
Description:Males; black zig-zag patterning on white to bluish background. Females have browner pattern on reddish background. Characteristic V shaped mark on head. Underside grey or black with pale spots.
Habitat:Wide range of lowland and upland, dry and wet with suitable basking areas such as sand, rocks or quarries and railway embankments. Hibernate in winter, usually underground on south-facing bank free from flooding and frost.
Young:Young: Eggs hatch within females body and 6 – 20 live young born in August.
Diet:Frogs, toads, lizards, slow worms, small mammals and birds eggs.
Population:Pre-breeding season estimated to be 130,000.