Adder: Ecology and Welfare
The adder (Vipera berus) is Britain's only venomous snake and one of its most misunderstood. Declining significantly across much of its range, it is a fully protected species that plays a valuable ecological role and deserves the same welfare consideration as other native wildlife.
Ecology and Habitat
Adders inhabit heathland, moorland, woodland edges, grassland with scrub, and coastal areas — typically open, sunny habitats with dense cover nearby. They are ectotherms requiring basking sites for thermoregulation. Adders need a mosaic of habitat features: south-facing banks or clearings for basking, dense vegetation for cover and hunting, and hibernation sites (deep within vegetation, under large stones, or in small mammal burrows) for overwintering from October to March/April.
Diet consists of small mammals (primarily field voles and mice), lizards, and occasionally nestlings — captured using venom from their distinctive fangs. Venom is primarily used for prey capture rather than defence.
Conservation Status
Adder populations have declined sharply, with local extinctions in many areas where they were previously common. Habitat loss (scrub encroachment of heathland, conversion of grassland to arable, and loss of woodland structure diversity), fragmentation, persecution, and disturbance are primary drivers. The adder is listed as a Priority Species in the UK Biodiversity Action Plan.
Conservation management involves heathland restoration, scrub management to maintain open south-facing areas, ride and glade management in woodland, and connectivity between populations through wildlife corridors.
Welfare and Persecution
Adders suffer from deliberate killing (persecution) driven by misplaced fear. Killing or injuring adders is illegal under the Wildlife and Countryside Act 1981. Public education emphasising that adders are shy, non-aggressive animals that bite only when handled or trodden on is vital for reducing persecution.
Dog bites are the most common cause of adder envenomation in Britain. Prompt veterinary treatment significantly reduces mortality — antivenom is available and effective. Most affected dogs and humans recover with appropriate treatment.
Handling and Ecological Survey
Licenced ecologists handling adders for survey or mitigation purposes must use appropriate equipment (snake hooks, tubes, protective gloves) and follow welfare protocols minimising handling stress. Thermal regulation during handling is important — cold adders are torpid and less likely to strike but also more physiologically vulnerable to stress.