The adder (Vipera berus) is Britain's only venomous snake and faces population decline from habitat loss, illegal killing, and road mortality — all significant welfare concerns.
Adder welfare is poorly understood compared to mammals, but their physiological complexity and nociceptive responses indicate welfare relevance. Illegal persecution causes acute welfare harm through crushing, cutting, and other methods used by people who fear or dislike snakes. Road mortality causes traumatic injury and death. Adders use thermoregulation sites including road surfaces which increases collision risk. Welfare monitoring is challenging — population assessments use transect surveys rather than individual monitoring. Habitat management including heathland restoration, creation of sunny log piles and rock piles for basking, and preservation of woodland-heath interfaces provides both conservation and individual welfare benefit by supporting healthy, well-nourished populations. Reptile Conservation Trust and ARG UK coordinate adder conservation nationally.