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Providing evidence to improve practice

Individual study: Effectiveness of wildlife guards at access roads

Published source details

Allen T.D., Huijser M.P. & Willey D.W. (2013) Effectiveness of wildlife guards at access roads. Wildlife Society Bulletin, 37, 402–408


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

Install wildlife exclusion grates/cattle grids Terrestrial Mammal Conservation

A replicated, before-and-after study in 2003–2010 at two roadside areas in Montana, USA (Allen et al. 2013) found that wildlife exclusion grates reduced crossings of a major highway by deer Odocoileus spp., but not by black bears Ursus americanus. After installing wildlife exclusion grates, a lower proportion of deer approaching the road subsequently crossed it (6%) than did so before grates were installed (44%). The proportion of black bears crossing the road, out of those approaching it, was not significantly different after grates were installed (62%) compared to before they were installed (87%). Between October 2004 and November 2010, fencing was installed along the roadside. Single exclusion grates were fitted at each of two junctions with minor roads. Grates were 6.8 m wide and 6.6 m long. In June–October of 2003–2005, eight 100 × 2 m areas were coated with sand to record animal tracks. Using these data, the percentage of animals that crossed the road was calculated. Wildlife cameras were placed at both grates between July 2008 and July 2010. The number of times an animal was ≤2 m from grates and whether it subsequently crossed were recorded.

(Summarised by Phil Martin)