The potential demise of a population of adders (Vipera berus) in Smygehuk, Sweden

Abstract.—In 1999 and 2004, we published reports on how the introduction of 20 males into a severely inbred and isolated population of Adders halted its decline towards extinction. The introduction significantly enhanced the population’s genetic variability, which resulted in a dramatic increase in offspring viability and a rapid increase in numbers.