Reptiles · Squamata · Viperidae

Adder

Vipera berus

Least Concern

The species is abundant and widely distributed; it faces no significant short-term risk. See full glossary

It is the only venomous snake native to the United Kingdom and one of the highest-latitude snakes in the world, living inside the Arctic Circle in Scandinavia.

Weight

50 g – 180 g

Size

50 cm – 90 cm

Lifespan

15 years

Diet

Carnivore

Feeds mainly on other animals.

Activity

Diurnal

Active mainly during the day.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Easy

Temperate forestTundraCarnivore Diurnal Solitary Reptile Temperate forest Tundra

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Fun facts

It is the only venomous snake native to the United Kingdom.
It is ovoviviparous, an adaptation that lets it survive in cold climates.
Many females do not breed until their eighth season.

Life cycle & biology

Skeleton type: Vertebrate - internal bony skeleton (reptile)
Habitat & environment: A wide range of habitats across Europe and northern Asia: heath, woodland, grassland and rocky ground, as far as the Arctic Circle
Birth weight: 16-23 cm long at birth (born live, ovoviviparous)
Size at birth: 16-23 cm long at birth, its venom already working
Sexual maturity: 3-4 years (though many females do not breed until their eighth season)
Gestation / incubation: 3-4 months of gestation
Litter / clutch size: 3 to 20 young per litter (average 8-10)

Sources consulted: iNaturalist; Universitat Pompeu Fabra (bioinformatics project); PMC (intermittent reproduction study); Animal Diversity Web; A-Z Animals; Wildlife Online; Animalia.bio; PMC (seasonal mortality study)