Potential of restored gravel pits to provide suitable habitats for Eurasian otters in anthropogenic landscapes

Abstract

In anthropogenic landscapes, which are usually characterized by the existence of highly heterogeneous patchworks of habitats with different conservation status, restored gravel pits have the potential to play a conservation role for semiaquatic species such as Eurasian otters (Lutra lutra). Here, we report an otter habitat suitability analysis on a complex fluvial system in an anthropogenic landscape to understand the role of different artificial water bodies (i.e. irrigation channels and ditches) and natural water bodies (i.e. rivers) related to a restored gravel pit lagoon system as providers of suitable habitats for otters. We implemented seven sampling campaigns during 2016 and 2017 consisting of 19 transects across all existing types of water bodies. We integrated 34 environmental variables with otter habitat use, measured by three spraint marking intensity indicators. We found that otter use of water bodies was not related to the natural or artificial origin of the water. Three key factors influenced habitat suitability: riparian vegetation tree cover, forestland use (either natural or planted) within 100 m from the banks, and the level of human disturbance. Our results suggest that otters' tolerance of human activities might be lower in key areas of their territory compared to areas they pass through or explore. We argue that restored gravel pit lagoon systems can potentially play a role in providing suitable habitats for otters in anthropogenic landscapes.