Effectiveness of mitigation of the impacts of a new road on horseshoe bats Rhinolophus ferrumequinum in Wales, UK

Published source details Davies J.G. (2019) Effectiveness of mitigation of the impacts of a new road on horseshoe bats Rhinolophus ferrumequinum in Wales, UK. Conservation Evidence, 16, 17-23.
Share Tweet Email

This study is summarised as evidence for the following.

	Action	Category
	Install underpasses or culverts as road/railway crossing structures for bats Action Link

Install underpasses or culverts as road/railway crossing structures for bats

A replicated, site comparison study in 2011–2013 and 2015 of eight structures under a road in Wales, UK (Davies 2019) found that larger underpasses and a ‘box’ culvert had higher activity of greater horseshoe bats Rhinolophus ferrumequinum within them than over the road above, but smaller ‘pipe’ culverts did not. Higher greater horseshoe bat activity was recorded within three large underpasses (68–97% of bat passes) and a ‘box’ culvert (88%) than over the road above (underpasses: 3–32%; box culvert: 12%), although the results were not tested for statistical significance. Three smaller ‘pipe’ culverts had lower greater horseshoe bat activity within them (15–40% of bat passes) than over the road above (60–85%). Three ‘pipe’ culverts (0.75, 1 and 1.5 m diameter), a ‘box’ culvert (1.8 x 3 m) and three underpasses (one for cattle: 2.7 x 2.4 m; two for horses: 3.5 x 4 m; one open-span: 8.95 x 3.5 m) were installed under a new road in 2011. All were on/near bat commuting routes or foraging habitat and 4.3–6.5 km from a greater horseshoe bat roost. In May–September, bat detectors within and above each structure recorded bat activity for one night/month (2011, 2012 and 2015) or on three occasions (2013). Surveyors using night-vision equipment confirmed bats were flying through or over the structures.

(Summarised by: Anna Berthinussen)