The adder, Britain's only venomous snake, has declined significantly in recent decades due to heathland loss and fragmentation. Small isolated populations face inbreeding and local extinction.
Isolated adder populations face both demographic and genetic welfare threats. Small populations experience inbreeding depression — reduced immune function, smaller litter sizes and higher juvenile mortality. Genetic rescue through translocation of individuals from healthy populations has been shown to reverse inbreeding effects within two generations. Adders killed on roads represent irreplaceable losses for small isolated populations. Despite their venomous nature, adders are shy and non-aggressive — almost all bites occur when snakes are handled or accidentally stood on. Education reducing unnecessary fear reduces persecution of this protected species.