A multi-scale analysis of the habitat associations of European otter and American mink and the implications for farm scale conservation schemes

Establishing relationships of species occurrence with environmental variables is important to define and develop species conservation schemes. The character of the riparian environment which supports populations of otter (Lutra lutra) and mink (Neovison vison) was investigated across spatial scales. Both species were positively associated with increased habitat diversity, the provision of natural land cover and a reduced level of urbanisation. However, mink were most closely associated with immediate riparian conditions whereas otters were associated more strongly with broad scale environmental characteristics. We argue that the benefits of habitat improvements may be seen more quickly in the occurrence of mink, a non-native pest species, than in the occurrence of the native otter. This has implications for the perceived benefits of conservation schemes which are applied at a fine scale, with particular relevance to farm-based conservation prescriptions such as agri-environment schemes. We show that mink presence is associated with higher levels of riparian bird diversity, a pattern which was not observed with occurrence of otter. It may be inevitable that conservation schemes benefit populations of both desirable and undesirable species. The present study demonstrates the importance of considering scale in animal ecology when developing conservation strategies. The use of specialist species with large home ranges to reflect the success of conservation schemes which are applied on a farm scale should be avoided. Effective conservation schemes may require specific pest species monitoring and management.