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Providing evidence to improve practice

Individual study: Effectiveness of wildlife underpasses and fencing to reduce wildlife-vehicle collisions

Published source details

McCollister M.F. & van Manen F.T. (2010) Effectiveness of wildlife underpasses and fencing to reduce wildlife-vehicle collisions. The Journal of Wildlife Management, 74, 1722-1731


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

Install one-way gates or other structures to allow wildlife to leave roadways Terrestrial Mammal Conservation

A replicated, controlled study in 2000–2007 along a highway in North Carolina, USA (McCollister & van Manen 2010) found that barrier fencing with escape gates and underpasses facilitated road crossings by a range of mammals but did not reduce road casualties. A similar rate of mammal road casualties was recorded over one year on road sections with fencing, escape gates and underpasses (5.0/km) as on sections without (5.1/km). A four-lane highway was constructed with three underpasses. Barrier fencing, 3 m high, was installed ≥800 m along the highway from each underpass. Gates allowed trapped animals to escape the highway. Road deaths were recorded along 6 km of road with fencing and underpasses and 11 km without, twice/week, from July 2006–July 2007.

(Summarised by Rebecca K. Smith)

Install barrier fencing and underpasses along roads Terrestrial Mammal Conservation

A site comparison study in 2000–2007 along a highway in North Carolina, USA (McCollister & van Manen 2010) found that underpasses and barrier fencing facilitated road crossings by a range of mammals but did not reduce road casualties. Camera traps showed crossings through the three underpasses by white-tailed deer Odocoileus virginianus (2,258 times), raccoon Procyon lotor (125), American black bear Ursus americanus (15), bobcat Lynx rufus (11), gray fox Urocyon cinereoargenteus (eight), Virginia opossum Didelphis virginiana (six), rabbits Sylvilagus spp. (two) and Canis spp. (two). Track counts indicated an additional 3,552 mammal crossings by 15 species, with 90% by white tailed deer. A similar number of mammals was killed over one year on road sections with underpasses and fencing (5.0/km) as on sections without (5.1/km). A four-lane highway was constructed with three underpasses. Barrier fencing, 3 m high, was installed ≥800 m along the highway from each underpass. Gates allowed trapped animals to escape the highway. Underpass use was monitored by 2–3 camera traps /underpass. Twice-weekly track surveys were conducted (on 2.5-m-wide plates across underpasses). Road deaths were recorded along 6 km of road with fencing and underpasses and 11 km without, twice/week, from July 2006–July 2007.

(Summarised by Rebecca K. Smith)