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Individual study: Effectiveness of short sections of wildlife fencing and crossing structures along highways in reducing wildlife-vehicle collisions and providing safe crossing opportunities for large mammals

Published source details

Huijser M.P., Fairbank E.R., Camel-Means W., Graham J., Watson V., Basting P. & Becker D. (2016) Effectiveness of short sections of wildlife fencing and crossing structures along highways in reducing wildlife-vehicle collisions and providing safe crossing opportunities for large mammals. Biological Conservation, 197, 61-68


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

Install barrier fencing along roads Terrestrial Mammal Conservation

A 2016 review of fencing studies from USA, Canada and Sweden (Huijser et al. 2016), found that longer fencing along roadsides led to a greater reduction of collisions between large mammals and cars than did shorter fence sections. Results were not tested for statistical significance. Fences reduced collisions between large mammals and cars more in road sections fenced along >5 km (average 84% reduction in relation to before fencing) than in sections fenced along <5 km (average 53% reduction). The review identified 21 fenced road sections (18 from the USA, two from Canada and one from Sweden). Fences were 0.6–33.8 km long and 2.1–2.5 m high. Large mammals targeted by surveys included white-tailed deer Odocoileus virginianus, moose Alces alces, roe deer Capreolus capreolus, mule deer Odocoileus hemionus, elk Cervus canadensis and bighorn sheep Ovis canadensis.

(Summarised by Ricardo Rocha)

Install barrier fencing and underpasses along roads Terrestrial Mammal Conservation

A replicated, site comparison study in 2013 along a highway in Montana, USA (Huijser et al. 2016) found that underpasses connected with long roadside fences were used by similar numbers of large mammals compared to those with no fences or very short fences. The rate of large mammal crossings through underpasses connected to 6.1–6.2-km-long roadside fences (0.44 mammals/underpass/day) and 1.4–2.7-km-long fences (0.77 mammals/underpass/day) was not significantly different to the rate crossing through underpasses with no fencing or with fences up to 0.4 km long (0.22 mammals/underpass/day). Mammals identified using underpasses were white-tailed deer Odocoileus virginianus, mule deer Odocoileus hemionus, American black bear Ursus americanus, mountain lion Puma concolor, grizzly bear Ursus arctos and elk Cervus canadensis. Twenty-three underpasses were monitored along US Hwy 93 North. Roads were fenced alongside underpasses for 0.0–6.2 km length with 2.4-m high fencing. Wildlife crossings were monitored using ≥1 camera trap/underpass in January–December 2013.

(Summarised by Ricardo Rocha )

Install barrier fencing and underpasses along roads Terrestrial Mammal Conservation

A study in 2012–2013 along a highway in Montana, USA (Huijser et al. 2016) found that underpasses, in areas with roadside fencing, were used by white-tailed deer Odocoileus virginianus for crossing the road more often than was the road surface. This result was not tested for statistical significance. There were 727 road crossings with 721 by white-tailed deer, three by American black bear Ursus americanus and three by either this species or grizzly bear Ursus arctos. Eighty-two percent of all crossings were through underpasses and 18% were above the road. Ten fenced underpasses were monitored along US Hwy 93 North. Underpasses were 2–5 m high and 4–40 m wide. Fences were 2.4 m high and 3–256 m long. The proportion of wildlife crossings did not change with fence length (data presented as regression results). Between June 2012 and October 2013, road crossings were monitored for two weeks/underpass using one camera trap at each fence end and at least one at an underpass entrance. Only highway crossings in which animals entered or exited underpasses or accessed or left the highway at a fence end (not returning within ≤3 minutes) were considered.

(Summarised by Ricardo Rocha )