The adder is Britain's only venomous snake and is in significant decline. Its welfare depends on undisturbed basking sites, prey availability and connectivity between populations.
Adder welfare is primarily threatened by habitat fragmentation and direct persecution. Individual adders that emerge in spring to bask at traditional sites where they have been killed by humans or dogs do not return to those sites - population decline follows. Adders require access to both warm basking sites and dense cover for thermoregulation, feeding and refugia. Without connectivity between suitable patches, populations become isolated and face genetic bottlenecks. Welfare-conscious heathland and scrub management maintains the mosaic of open and dense habitat that allows adder populations to fulfil their biological requirements.