Adder (Vipera berus)
A rustle in the bracken. A flash of zig-zag and it’s gone! Our most striking snake: the adder! You’ll never forget the excitement for seeing your first one.
Adders are found throughout Britain, right up to the north of Scotland, but their secretive nature and camouflaged markings mean they often go unnoticed. This can sometimes be a good thing – as the only venomous snake in the UK they have often been persecuted in the past. Adder bites are painful but rarely fatal and usually only occur if the snake is disturbed or deliberately antagonised. Adders are a sturdy looking snake and are easy to distinguish from the other native species.
| Identification | Adults 60-80 cm in length. Stocky body. Males generally grey with black markings. Females generally light brown with dark brown markings. Very young individuals reddish-brown or ginger but zigzag pattern still visible. Completely black (melanistic) adders quite common in some areas. Zigzag pattern down centre of the back and a ‘V’ or ‘X’ shaped marking on the head.
Reddish iris with vertical pupil. |
| Distribution | Native to the UK. Found throughout the UK but absent from Ireland. Widespread throughout Europe and across Russia. Range extends north into the Arctic Circle. |
| Ecology | UK’s only venomous snake. Bites are painful but rarely dangerous. Found in open habitats with plenty of sunlight such as heathland, moorland, open woodland and sea cliffs. Rarely stray into gardens. Active during the day hunting for small mammals, amphibians, insects and birds. Actively hunts prey in warm weather. Uses a ‘sit and wait’ technique when it’s cold. Kills prey with venomous bite and swallows them whole. |
| Predators and other threats | Populations in the UK are declining. Threatened by human persecution and loss of habitat. Predators include birds of prey but also pheasants, crows, etc. |
A year in the life…Spring
Adults emerge during March/April and mating takes place in April/May. Males are quite territorial and will ‘dance’ a duel as they compete for a female. Female Adders do not lay their eggs, instead they incubate them internally. Spring can be a common time for people or pets to be bitten by Adders as the snakes are sluggish and less able to escape quickly. Medical attention should be sought immediately, but bites are rarely fatal in pets and even more rarely in humans.
Summer
Females ‘give birth’ to live young in late summer (August/September). Litters range from three to 20 and the young will stay with the mother for a few days. Adders spend their time in undisturbed habitats such as open woodland, moorland and heathland and are rarely encountered in gardens, though this depends on surrounding habitats.
Autumn
Adders spend autumn preparing for hibernation. Adults usually feed on small mammals and lizards (this means their venom does not need to be particularly potent).
Winter
The snakes hibernate between November and March.
Studies and Actions from Conservation Evidence
The information below is from the Conservation Evidence website.
Studies and Actions from Conservation Evidence in detail
| Action | Effectiveness | Link | Froglife Advice |
| Create artificial refuges, hibernacula, and aestivation sites | Awaiting assessment | https://www.conservationevidence.com/actions/3720 | https://www.froglife.org/learning-zone/wildlife-at-home/ |
| Translocate reptiles away from threats: snakes and lizards | Awaiting assessment | https://www.conservationevidence.com/actions/3731 | |
| Breed reptiles in captivity: snakes- elapids | Awaiting assessment | https://www.conservationevidence.com/actions/3750 | |
| Protect brownfield or ex-industrial sites in urban areas | Awaiting assessment | https://www.conservationevidence.com/actions/3478 | |
| Install barriers and crossing structures along roads/ railways | Awaiting assessment | https://www.conservationevidence.com/actions/3507 | https://www.froglife.org/what-we-do/education/london-t-o-a-d/t-o-a-d-campaign/ |
| Install tunnels/ culverts/underpasses under roads/ railways | Awaiting assessment | https://www.conservationevidence.com/actions/3508 | https://www.froglife.org/what-we-do/education/london-t-o-a-d/t-o-a-d-campaign/ |