Restoration programmes and the development of a natural diet: A case study of captive-bred European mink

As part of a conservation initiative, we released captive-bred individuals of European mink (Mustela lutreola) onto a Baltic island 'sanctuary', Hiiumaa (Estonia), and investigated the development of their diet in the wild. Fifty-four animals out of the 172 released were equipped with radio collars and tracked in 2000-2003 intensively after release. Based on the analysis of the contents of 564 collected scats, we monitored how the diet of released individuals changed after release and how this was affected by habitat and by season. Diet changed as they adapted to the wild: some prey consumed immediately after release were later substituted with prey more typical of wild European mink elsewhere. The mink's tendency to take typical prey increased (crayfish, 3; fish, 1. 5; and small mammals, 2 times), while the proportion of atypical prey decreased more than five times in 60 days after release. Once established in the wild, the composition of the diet and its variation between seasons, habitats or weather conditions were similar to that reported elsewhere for wild European mink. There is no indication therefore that the components of the diet provided in captivity persisted in the wild after the adaptation period. We suggest that the adaptation of released carnivores to natural prey merits more attention in reintroduction projects. © 2012 Springer-Verlag.