Pine martens were extirpated from most of Britain by persecution and habitat loss. Their return to England and Wales is benefiting red squirrel conservation through suppression of grey squirrels.
Pine marten reintroduction welfare involves both the welfare of translocated animals and the broader ecosystem effects of their presence. Translocated martens experience significant stress during capture, transport, and release into unfamiliar territories. Mortality in the months following release can be high. However, successful establishment creates self-sustaining populations that benefit from predator-intact ecosystems. The knock-on welfare benefit for red squirrels -- released from competitive pressure by grey squirrels -- demonstrates how predator reintroduction can improve welfare for multiple species simultaneously.