The response of water voles Arvicola amphibius to 'displacement' when using water draw-down and habitat removal in grazing marsh habitat, lowland England

Abstract

Displacement is a form of mitigation that involves the removal of habitat to relocate water voles Arvicola amphibius from <50m sections of watercourse where their presence conflicts with small-scale development works. The technique is permitted under license in England to minimise negative impacts of development on water voles that are protected under UK law. Despite its widespread use, displacement as a mitigation tool is controversial due to the paucity of evidence relating to its effectiveness and disparity in the methods used to remove habitat. This study aimed to investigate the response of water voles to displacement when using a combination of water draw-down and vegetation removal. We radio-collared 20 water voles and used recapture data to monitor the movement and fate of individuals at three displacement sites and two control siteslocated in grazing marsh habitat in England during spring 2017. We found that all voles moved to alternative habitat following the removal of vegetation and water and no individuals were discovered in the works area following a destructive search of burrows seven days later. There was no significant difference between the fate and movement of displaced and control individuals. We conclude that displacement of water voles was effective when using both water draw-down and vegetation removal, but recommend further research is carried out to investigate other potentially confounding factors including population density and habitat type.