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Individual study: When flyways meet highways - The relative permeability of different motorway crossing sites to functionally diverse bat species

Published source details

Abbott I.M., Butler F. & Harrison S. (2012) When flyways meet highways - The relative permeability of different motorway crossing sites to functionally diverse bat species. Landscape and Urban Planning, 106, 293-302


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Install overpasses as road crossing structures for bats Bat Conservation

A replicated, site comparison study in 2008 at six overpasses over a road in agricultural and woodland habitat in southern Ireland (Abbott et al. 2012) found that three bat species or species groups flew over overpasses but 39–75% of activity was recorded over the road below them, and lower activity was recorded on overpasses than in adjacent habitats. Overpasses were used by three bat species or species groups (common pipistrelle Pipistrellus pipistrellus, soprano pipistrelle Pipistrellus pygmaeus, Myotis spp.), but 39% of common pipistrelle passes, 49% of soprano pipistrelle passes, and 75% of Myotis spp. passes were recorded over the road below overpasses. Bat activity was lower (by >10%) on overpasses than in adjacent habitats (data reported as statistical measures). The overpasses (8–11 m wide x 6–11 m high x 58–76 m long) had minor roads over them. The motorway (65–70 m wide) had four lanes carrying an average of 20,000 vehicles/day. Bat detectors recorded bat activity above and below each of the six overpasses and simultaneously at two adjacent linear features on two nights in May–September 2008.

(Summarised by Anna Berthinussen)

Install underpasses or culverts as road crossing structures for bats Bat Conservation

A replicated, site comparison study in 2008 at 13 under-motorway crossing routes in agricultural and woodland habitat in southern Ireland (Abbott et al. 2012), recorded more bat activity in under-motorway routes (underpasses or rivers bridged over by the road) than over the road above them, or in adjacent habitats. More bats were recorded in under-motorway routes (underpasses: 662 bat passes; river bridges: 4,692 bat passes) than over the road above them (above underpasses: 45 bat passes; above river bridges: 96 bat passes). Bat activity was also greater (by >10%) at under-motorway crossing routes than in adjacent habitats (data reported as statistical measures). Six bat species or species groups were recorded in total (see original paper for data for individual species). The motorway (65–70 m wide) had four lanes carrying an average of 20,000 vehicles/day. Seven underpasses (5–17 m wide x 4–10 m high x 26–63 m long) and six river bridges (6–420 m wide x 3–19 m high x 23–39 m long) were surveyed. Bat detectors recorded bat activity above and below each of the 13 structures and simultaneously at two adjacent linear features on two nights in May–September 2008.

(Summarised by Anna Berthinussen)