Like so many animal and plant species that have been introduced to Britain by humans, mink have thrived here because, compared to home, they have fewer competitors, predators and diseases to keep their population in check. Also in their favour is that many native birds and mammals here have evolved in the absence of a web-footed predator that has a taste for a broad range of prey, so they are vulnerable to being eaten by this relative newcomer. Some of our most cherished wildlife, like kingfishers and sand martins, fall victim to mink, but the creature to have suffered most is the water vole – ‘Ratty’ of Kenneth Grahame’s Wind in the Willows. Over 95% of Britain’s water voles have been lost in recent decades, and research has shown that mink are the single most significant cause of this catastrophic decline.