The recovery of otters in UK waterways has been associated with displacement of invasive American mink, providing ecological and welfare benefits for native prey species.
The otter-mink ecological interaction has welfare implications across multiple species. Recovering otter populations that suppress mink densities reduce predation pressure on water voles and ground-nesting birds, improving welfare for these prey species at population level. However, individual mink displaced by otters face competition for territory and food resources that may increase stress and mortality in displaced animals. The aggregate welfare calculus favours otter recovery: the welfare benefit to numerous prey species previously subjected to high mink predation pressure outweighs the welfare cost to a non-native species whose presence has itself caused widespread welfare harm to native wildlife.