Adders are the UK's only venomous snake and face illegal persecution from people who kill them out of fear, threatening populations that are already declining.
Adders illegally killed by humans die from crushing, cutting, or other violent methods causing acute suffering. Snakes are sentient animals with pain receptors and complex nervous systems; their killing causes morally significant harm. Adder bites in retaliation to handling or accidental encounter involve defensive behaviour from an otherwise non-aggressive species. Population declines from persecution, habitat loss, and predation by introduced species cause welfare harms at population level through isolation and inbreeding in fragmented populations.