Water voles have experienced the steepest population decline of any British mammal -- over 90% since the 1970s. American mink introduced through the fur trade are the primary driver, alongside habitat loss.
Water vole welfare involves both the individual suffering caused by mink predation and the population-level collapse that has eliminated them from most of their historical range. Mink predation of entire family groups in burrows is a welfare event affecting multiple individuals simultaneously. The stress of living in a landscape with high mink density reduces reproductive success and increases vigilance costs. Conservation mink control that enables water vole recovery improves welfare for recovered populations even as it involves welfare trade-offs for controlled mink.